The breather tube is a direct port to the inside of the left side rocker cover, and air pressures there are the same as air pressures in the crankcase. I unhooked the breather tube from the air filter housing and attached my vacuum gauge to that hose. See the description at 3:40 of the video. Yes, I think the dipstick tube would work, but I chose to do this exactly as described by Chrysler as a corporate guideline for their OEM mechanics. Other, older designs may not leak internally....
Spark knock/Detonation results from incomplete combustion. Once the spark plug is oil fouled and no longer firing, essentially you have oil and fuel exposed to compression pressures. The heat alone will bake the oil, causing build up on the piston. This contributes to raising the overall compression ratio of that cylinder. Because CR has been raised, cylinder temperature is also considered excessive. The heat alone can pre-ignite the fuel long before TDC. With old spark plugs, these increases in pressure/temperature can and will crack the porcelain, which now leads to a compression leak. I've seen plug wires blow right off of a faulty SP. I have also seen heavily corroded plug wires(spark plug porcelain was leaking compression, moisture being a byproduct of combustion contaminated the plug boot) When this plenum pan gasket fails, it will certainly misfire because it is burning oil, but it won't be burning oil from spark ignition for long because the SP will become fouled. Thank you for taking the time to educate the general public, this field is too diluted with ignorance and the only way we can eliminate it is to educate others and of course have fun learning at the same time.
What a brilliant description of the ugly cascade that happens when the pan gasket fails. Your explanation of the cause of spark knock is understandable and very believable. Thanks for recording it here, Jarin! Dave
To measure manifold vacuum, I use any available hose that attaches to the intake manifold (the brake booster tubing was convenient). But that was not the test, it was just a demo to show what my plenum vacuum was doing. Yes, when I did the test I did measure crankcase pressure by disconnecting the breather tube, but remember to disconnect and clamp off the tubing connecting the intake manifold to the crankcase. You want to be very careful to do this correctly since you normally have some vacuum in the crankcase, coming from the PCV tubing. If you don't properly obstruct that PCV pathway, you'll get a false positive. This video has opened up a surprising debate as to how sensitive the test is. Official Chrysler documents say that there is no meaningful leak if the test is negative, but many armchair internet experts say the test is insensitive. I don't know if this is corporate denial or whether those people are wrong.
Hi Spelukered! Watching your videos and trying to diagnose my 02 ram 1500 5.9l 360..I am having an intermittent misfire on cylinder #7. Replaced tps, 02 sensors, spark plugs, plug wires.. It shakes hard on start up but will go away if you turn off the truck and turn it back on. Occasionally get code P0172.. Running rich. Any comments would be greatly appreciated.
This is tricky. The first thing I would do would be to put the secondary ignition on a labscope, and I uploaded a short video of that last week. If one injector is pissing fuel, that makes the bank 1 sensor 1 see rich, which makes the computer reduce fuel to all the cylinders on that bank, so all the other cylinders look lean on the scope. Or if it's a bad plug or wires, sometimes the scope pins that down easily, as I showed in the video. Unfortunately few of us backyard mechanics are lucky enough to have access to a scope. One of the things that is very poorly paid for professional technicians is diagnostic time, so one option would be to ask for advice from a pro, even if you end up doing the work yourself. It may save you money in the long run because you are less likely to play the game of replacing normal parts. Alternatively you could do a few simple tests, like hooking up a diagnostic scanner that is capable of live data to be sure both new O2 sensors are behaving normally, etc. In these older cars, sometimes it's nice to be sure there is no mechanical issue by doing a compression test first before you get into discussion about the costs of repair. Good luck!
Well im not losing oil,the engine runs smooth and steady for a 318 but I believe i have weak vacuum do to, under throttle the vents default to DEF and the 4x4 is sluggish to engage. I did do that gasket on my 97 with a 360 and it really wasn’t a bad job but obviously I don’t wanna “fix” something not broken
Just removed an 89 Ford Plenum. Still not sure, did not know of this test. The gasket even if not leaking was super hard, flat and brittle shattering to pieces so an improvement but probably would have been fine as long as not leaking. Even a new one can....I will do this test after putting in the new one and make sure. Thanks!
One last thing I could think of. You had mentioned that your idle was rough and you had a slight misfire at idle. I was wondering if your scanner offered misfire counters and if so, you could take a look at that. If not, possibly a power test on each cylinder.
That's good feedback, it's worth noting that any test has sensitivity issues. I was surprised to read in the Chrysler manuals that they are so dogmatic about the issue, at least on their official documents. On my vehicle the power is still excellent and I've never had pinging. Really, it's running better than ever this year, even without a new plenum pan. I'm a little disappointed since I was looking forward to doing it.
I worked on a 2001 3.9L Dakota that had misfire on cylinders 2 & 6. I changed the spark plugs and got cylinder 2 cleared up. I sprayed brake parts cleaner onto intake where it contacts the head with engine running. As I sprayed the brake parts cleaner onto intake on cylinder 6, the engine surged. Ah Ha! Intake gasket was cracked there. So I took the intake off, went with the Hughes aluminum plate plenum kit, and replaced the intake gaskets. It runs like a dream now. I had about $300 in parts total with full tune-up by doing it all myself.
heyy i saw a vid you posted. had a part number for the intake filter box gasket. i cant find that vid. do you happen to know tht number or which vid that might've been? thanks man
I’m really hoping you can help me out on this, I have a 96 Dodge Ram 1500 5.9 and it idles at 1400 rpms and when it’s running and u pull the dipstick it’s sucks air into it and when u plug the hose to the air filter it idles down to 800 and when you plug the hose from the break booster it also idles down to 800 rpms. I replaced all my sensors and checked for vacuum leaks but I can’t find any and I replaced my throttle body gasket. Any ideas?
Vacuum leak, for sure. The brake booster improvement is interesting, since I wouldn't think a plenum pan gasket leak would cause a leak at the brake booster. Likewise I wouldn't think a brake booster leak would cause vacuum to appear at the oil fill tube, so you may have two separate problems. If you don't have a smoke machine, first check for a disconnected hose and do a careful inspection. A stuck open PCV valve can cause vacuum to leak into the crankcase, and replacing that is a lot easier than replacing the plenum pan, so I'd check your PCV valve first. Make sure it rattles, and I'd probably do the procedure shown in this video to formally test the plenum pan. Notice that when you block off the PCV valve during that test, you take the PCV valve out of the equation. Regarding the brake booster, those can certainly leak, but first check for a bad hose or bad connection. There are videos here on RUclips explaining how to approach a leaking brake booster. Good luck!
Thanks for the informative, technical and concise video! I suspected a slight leak in my plenum (an '01 magnum 5.9) but for about $17 for a Harbor Freight gauge I confirmed no leak, similar to your test. Saves me a long weekend of replacing the gasket on a suspicion! I'm now considering a DIY smoke machine to look for other small vacuum leaks.
I've heard some guys say that a small plenum leak can paradoxically improve gas mileage, which when fixed worsens as the vehicle is able to achieve that magical 14.7:1 ratio. They make the point that the target of optimizing fuel ratio is to reduce emissions, with fuel economy being only a secondary goal. If the air fuel ratio is a little lean, the car has slightly better gas mileage but more emissions. Those reflash programs designed to improve gas mileage alter the target fuel ratios.
Yeah, you would be right more often than not. But in my case I have no oil usage and no pinging or performance difficulty. I have only poor gas mileage and slight variable intermittent shudder at idle. I was thinking the same as you, with the notion that fixing it early might reduce the chance of secondary damage if I caught it early. I"m still ready to do the plenum but I've paused for a bit to consider my options. Thank you for looking this over, I value your thoughts.
I had another look at the stepper motor counts on the IAC yesterday, Terry. Idle IAC counts after a long warm-up were almost at target at 50. However I like your theory about a small leak, and I'm making preparation to build a small smoke machine to look at that possibility more closely. Thank you for your ongoing input. Dave
Dave, one other thing and I'm sure you already know this. When you do your smoke test, make sure the engine is cold. When I'm doing smoke tests especially on the intake area, I like the engine to be cold. The reason is that when the engine is warmed up, sometimes the intake gasket can seal itself and hide small leaks. I'm looking forward to your next video and good luck.
It was the one where I cleaned the IAC motor and throttle body. I actually made my own out of cork one day, but given that the factory gasket is only a couple of dollars it doesn't make much sense to make your own. You don't necessarily need a tight fit there because above the throttle body a slight air leak doesn't count as a vacuum leak, and there's no MAF sensor. Below the butterfly valve is another story. No sweat, Richard, thanks again for watching.
Thanks for your response. It's an intermittent shudder at low rpm only, and I called it a misfire. However I have new software now (autoenginuity) and the misfire counter is not recording it. It's been going on for a long time, years, with no worsening except the fall of in gas mileage. What do you think about my borderline vacuum at idle, better at 2500 rpm? I think I'll do a smoke test to try and find a small vac leak, and I think I'll change out the PCV in case it isn't closing completely.
Thanks for looking this over, Terry. What I described as a misfire is more accurately described as a slight 'shudder' at idle, like it's about to stall. On the scanner misfire count is 0, and to be honest I'm not sure how to interpret the IAC counts. You're right, at idle the vacuum is on the low side, and I did try some carb spray looking for a vacuum leak and I didn't find one. I was a little surprised that vacuum at 650 rpm was 17 and at 2500 rpm it was 22 - maybe a small external leak?
Yes, possible. Rear main seals commonly leak on these vehicles, too. But leakage alone isn't causing your pinging or loss of power. My rear main leaks a little and I'm just watching it, since repair of a rear main is a big job. A compression tester is fairly inexpensive at Harbor freight or Princess Auto.
Excellent video. I performed your test and I definitely need to change the plenum gasket. I have pinging, excessive oil use and very poor gas mileage. I'll let you know how I make out.
I have the same thing going with my truck I too will be checking my gasket I also have two vacuum leaks a big one and a small one this may be one of them
I'm VERY happy you posted your experience here. You documented convincing direct evidence that the Chrysler test does have at least some false negatives, meaning that in the setting of clear signs one shouldn't be dissuaded from moving forward. In my case I'm not losing oil, yet, so I've held off for now. But I don't think I would hesitate if I were having more definitive symptoms.
yes, I'm hoping I don't have to do this job for my truck but it would always be good to have a good video on it, my 2000 dodge ram has 139,000 miles on it, its got the 5.9L
I was looking forward to it, Alex. I even have the Hughes kit, and I'm not returning it since it may be in the works one day. If I have to remove the plenum for another reason it will certainly be done. But at this point I'm not going there. Thank you for watching.
mine had failed, 98 ram 5.2 318 laramie ext cab, the model with no back suicide doors. i did a rebuild due to what i thought was a blown head gasket, i had water coming from exhaust..truck idled perfect, it ran perfect no misfires that u could see by running it or idling, had power i could burn the tires and never stall, well headgasket was warped just enough to allow leak, i had the number 8 misfire weve all been warned about.. but my plenum gasket was damn near completely gone. i didnt expect it and was luckily planning on changing it and already got it lol. it was so thin and wore away. id say 30% of gasket material was left..40% at best and thats pushing it..i have some dragster buddies who love buying old cars rebuilding them they race them till there sick of them then do it all over again, they helped me and they couldnt believe how good my truck ran at the time 250k miles, bad head gasket, it took 10-15m to overheat, almost no plenum gasket, oil pan gasket and valve cover gaskets, throttle body gasket gone, i had oil on the plugs, water pump had sheared some propeller fins off too you couldnt tell till disassembled. and untold ammounts of sludge builtup, mustve used 30 cans of carb cleaner..if it hadnt been over heating u wouldve said the truck ran perfect lol it was incredible.. i love the truck i still have it after 10 yrs ive had many vehicles come and go but not it..its my toy, my best friend, my one true love lol and it earned that, it wasnt an immediate thing
mine had failed, 98 ram 5.2 318 laramie ext cab, the model with no back suicide doors. i did a rebuild due to what i thought was a blown head gasket, i had water coming from exhaust..truck idled perfect, it ran perfect no misfires that u could see by running it or idling, had power i could burn the tires and never stall, well headgasket was warped just enough to allow leak, i had the number 8 misfire weve all been warned about.. but my plenum gasket was damn near completely gone. i didnt expect it and was luckily planning on changing it and already got it lol. it was so thin and wore away. id say 30% of gasket material was left..40% at best and thats pushing it..i have some dragster buddies who love buying old cars rebuilding them they race them till there sick of them then do it all over again, they helped me and they couldnt believe how good my truck ran at the time 250k miles, bad head gasket, it took 10-15m to overheat, almost no plenum gasket, oil pan gasket and valve cover gaskets, throttle body gasket gone, i had oil on the plugs, water pump had sheared some propeller fins off too you couldnt tell till disassembled. and untold ammounts of sludge builtup, mustve used 30 cans of carb cleaner..if it hadnt been over heating u wouldve said the truck ran perfect lol it was incredible.. i love the truck i still have it after 10 yrs ive had many vehicles come and go but not it..its my toy, my best friend, my one true love lol and it earned that, it wasnt an immediate thing
I have a 2000 Dodge Ram 1500 with a 360. It only has 125,000 miles on it. Just recently started running rough as it comes up to normal operating temperature. It runs fine when I first start the engine. After a bout 2 or 3 minutes it starts to run rough. After it comes up to normal operating temperature, in runs and idles fine. Cold engine=runs well and warm engine=runs well. In between, just for a minute or 2, not so good. Plenum?
Hard to say. I suppose a pan gasket could do that although it wouldn't be typical. As a first effort I would put the engine onto a scanner with real time data, looking at oxygen sensor values, fuel trim, IAC position valves, etc. Before going too far down the diagnostic pathway it would be wise to catch up on any overdue maintenance items such as air filter, plugs, distributor cap, etc as outlined in the owners manual. I wouldn't replace any other parts unless justified on the basis of diagnostic tests.
@@spelunkerd Plugs, wires, distributor cap, and air filter all replaced last year. I have two code readers but I don't think either one has real time data. No codes or engine light. I guess I will have a mechanic put it on a scanner. I am the kind of guy that isn't afraid to turn bolts and replace parts but my diagnostic abilities on automobiles is limited to what I can find on RUclips or forums. :)
@@4150CHF One other thing that I often forget when dealing with variable rough idle is the EGR valve. If your EGR is sticking open, or perhaps has cracked tubing, you could get a variable rough idle that might seem to improve as the vehicle warms up.
@@spelunkerd It doesn't "seem" to improve. It is very obvious that the idle is normal at initial start-up and then becomes rough after a two or three minutes and then becomes normal again after another minute or two. This is without exception. It happens every time, like clockwork.
I noticed at idle that the vacuum gauge had a very slow drift and then the needle would smooth out when you increased the rpm, which to me would indicate possibly a small vacuum leak on the manifold side. From your test of the plenum pan, it looks okay to me. Did you take a look at your IAC count value to see where it's at. If you did have a vacuum leak, the pintle on the stepper would shut off the passageway because of increased air. If you see a very low value or 0 then you have a leak. cont)
If I remember, your LTFT's and STFT's are about -1.5% and then normalizes after it warms up and I assume that this is for both banks. From those values, there really isn't anything showing out of the ordinary. In any event, take a look at the IAC count and see what you have. If there is a leak, it would show up here.
There is normally some oil there from the PCV so that's not a very reliable test. A compression tester is pretty cheap, but in your case it might be better to take it to a pro so that you can be more confident in the answer. A quick professional opinion might save you some dough in the long run and give direction (replace engine or cut your losses before spending more). Even if the pan is leaking, if no compression the problem is bigger....
Gee, any codes? The list of problems you describe are characteristic of a plenum leak, the lack of confirmation notwithstanding. Is yours a gen2 Dodge Ram? If it is, I think I would be inclined to go after that pan gasket anyway. Have you done a compression test to look for more serious problems? A bad cat should be an easy diagnosis. One option would be to take it to a pro for an opinion. You could still do the pan gasket yourself, but what you are asking is for a professional diagnosis....
You might want to check the wire routing - Chrysler put a lot of emphasis on correct routing in their dealers manual. I would do a compression test on that cylinder, and maybe a leakdown test. Is the injector there working properly? You might find more helpful advice on one of the forums -- I spend some time on the free forum at ericthecarguydotcom
I haven't returned the Hughes kit, thinking that at some point I'll have to do it. But for now that plan is on hold. I'm actually a little disappointed since I was hoping for a definitive fix and I was looking forward to trying to improve on what is out there as far as videos go.
Embossed on the intake manifold should be the firing order...1-8-4-3-6-5-7-2 as well as 12ft pounds of maximum torque. After doing close to 15 of these plenum pan gaskets, they generally leak closest to the bulkhead/firewall. Cylinders 8 or 7 which of course oil fouls the spark plugs compromising the secondary ignition system thus resulting in misfires, especially at idle. One thing to keep an eye on is once the engine is up to operating temperature, if higher than normal tach is present(rule out dirty throttle body, etc) chances are the engine is consuming oil. I take pressure readings(pressure being what you want to see indicated on a gauge) directly at the dipstick tube. Any large measureable amount of vacuum there is a red flag. On another note, I have re-used the manifold bolts(I do this for a living and know what I can and can't get away with) If I recall correctly, the pan bolts are 11mm and should be torqued to 7ft pounds or 84in pounds. After removing the intake manifold assembly, plug the intake runner ports and pour some water in the assembly. If you see water leaking out of the pan, well, you know what to do. This is similar to checking valve seats and stem seals(cylinder off obviously) Being a Dodge product, do not be surprised if an idle relearn has to be done after re-assembly is complete. Now is a good time to change the valve cover gaskets as well and make darn sure the PCV is not plugged up. During the removal process, don't even worry about the fuel rail, leave it alone(unless you want to replace injector O-rings) If I can think of anything else, I will post it later.
I have a 99 Dodge Ram 1500 every time I start my truck sounds like it’s sucking air in my carburador and if I keep my truck running it goes away but when I drive it up the hill it loses speed and I push gas and it goes slower that means my plenum gasket it’s bad
I did a video of cleaning the throttle body that might help. The other resource if you haven't already found it, is dodgeforumdotcom. Lots of traffic and some people with experience there. I would do a compression test on your engine first. With an engine that is almost 20 years old, worn rings causing oil loss and bad compression could explain everything.
Thank you. What I don't know is the sensitivity of this test, ie can I exclude gasket failure if the test result is normal? Chrysler say yes, but I'm not so sure. It sounds to me like most people don't bother to do the test, instead replacing the gasket and plenum when suspicious problems arise.
I'm burning out cats, taken it in twice and one guy says plenum gasket other guy says injectors. I'll try this test. Thanks. B3500 Van. First time I did the oem cat, second time was amazon, both burned out and my exhaust is super rich smelling, get 9-10 mpg.
Those are good thoughts. You might consider doing a compression test to be as sure as you can that more investment will be worthwhile. Pan gasket problems were unique to this generation of dodge ram.
If your magnum engine uses more than normal amount of oil per 500-1000 miles its the plenum gasket . It's that easy , this is nice , but over the top .
That's a good point, but I'm not sure I would be so confident, especially in old engines with suspected ring wear. Before committing to major engine work I would want to have all the objective information, perhaps even a compression test.
spelunkerd , I hear you , I like your video and how analytical you are . Quick way to tell , really easy is to take the air cleaner housing off , open the butterflies and look down with a flashlight and if there's oil its the plenum gasket . That's how I checked mine and it turned out to be the case . Really Good videos though !
I have a 99 dodge ram 5.2 v8 I'm TRYING TO SEAL ALL LOOSE ENDS IF I CAN GET ADVICE WHERE TO FIND LAYOUT/DIAGRAM LET ME KNOW SO I KNOW WHAT ALL PARTS ARE AND WHERE THEY GO/FUNCTION. I'd LIKE TO BE ABLE TO TAKE ENTIRE ENGINE APART AND KNOW WHAT EVERYTHING DOES ETC. gOD BLESS. p>S. GET SUM SWAG
+Jason Edward The most economical and accurate option is on online dealers repair manual, either alldatadiy or Mitchell. For a 5 year subscription (about $35) you get updated TSB's and the full dealer repair manual, with lots of additional detail. I wouldn't work on a car without it.
Thank you very much. Your video was simply and clearly explained and quite helpful. My '99 Ram 5.9 2500 manual trans, just out of nowhere, decided to fall flat upon even very light acceleration. I pulled a code P171B ('Left Bank Lean'). My test results were as exact as yours so at least now I know it 'shouldn't' be the plenum. No idle problem, pinging, backfire, detonation, etc. Just goes 'Bleeaahh' and dies flat out of breath. Always starts right back up and idles all day but same thing when you accelerate again. Also, 99's (at least this one) do not have a MAF sensor. Much appreciated.
Interesting. I'd be going for fuel delivery (fuel pump or fuel pressure regulator, etc), or maybe a clogged cat. I don't know if the '99 has a MAF sensor, but if it does then a dirty MAF can do the same thing (the '98 has only a MAP). I would take the air filter off and have a look there to make sure no rodents have made a nest that obstructs flow in the air intake somewhere. First thing I would do is measure fuel pressure from the Schraeder valve with acceleration and if that is OK then measure exhaust back pressure upstream of both cats. If you have a MAP like the '98, check that the little vacuum hose that comes off the MAP is connected correctly with no leak or crack in the tubing. Lack of difficulty at idle goes against a typical vacuum leak. Good luck. One word of caution, I would not start replacing parts before diagnosis. Getting a diagnosis from a pro often doesn't cost too much, and may be much less expensive than blindly replacing parts without proving they are bad first. So if I didn't have the tools necessary to make the diagnosis I wouldn't hesitate to get advice from a pro.
+Charles Rendine Ha ha! This morning I turned on the computer and found a video that describes a similar situation in a similar vehicle. Go to SouthMainAutoRepair here on RUclips, and find the recent video published today "Dodge Ram 5.9 gas, no power..." That one was running rich, clearly a clogged cat, he shows how to make the diagnosis. Let's hope yours is not that, a new cat is expensive. Yours is running lean, it could still be a fuel issue, so don't assume yours is the same. I hate to see old trucks like this hit the junk yard, if it were mine I would do it myself and try to keep it on the road. Good luck, please stop by and let us know how it turned out.
When the pan gasket leaks, it is over a long RTV line so something like a catch can doesn't work. Even so, the replacement is simple enough and very effective for these old trucks that have the defect. Many of these old trucks are already in the crusher, never experienced a leak, or have already been fixed. The standard replacement, a Hughes plate, is aluminum. So, if you place a magnet on your plenum plate you can quickly tell if it's been replaced with a Hughes kit. The tricky issue is regarding how much oil is too much, and whether there is even a leak! The dealer information says that if you don't have vacuum in the crankcase, the repair is not needed.
I didn't need a gauge. I took the oil filler cap off and right away there was a vacuum I could feel by placing my hand over the oil filler cap hole. I bought the Hughes kit and when I removed the intake the gasket was totally failed and blown out. My truck was pulling air from the crank case. Since the Hughes kits was installed I have more horse power and no more pinging climbing a hill.
Excellent point, that's a shortcut that experienced techs go to first, I forgot to mention it. Of course that shortcut is not as sensitive as doing the test as I did here. On internet forums, some people claim that this gasket fails so often in the gen II vehicles, it's not worth testing, just fix every one. I don't agree with that remark, but it does raise the interesting issue of false negatives. The official Chrysler line is not to fix it unless this test is positive, and if the leak is so small you can't detect crankcase vacuum, I would wonder whether fixing a tiny leak would make any difference. It certainly wouldn't help the dominant issue with these trucks, gas mileage.
I have a question regarding your 98' ram. The fog lights. I'm going to put fog lights in it. Reuters. Wires to fuse box and install the lights. Can you tell me how the switch works for a 98 for fog lights. Or I'll have to get a new switch
Mine doesn't have fog lamps but I scrolled through the dealer service manual for you on alldatadiy and I found some details about the fog lamp circuit and switch. When installed in some versions of the Ram, the fog lamp switch is on the right side of the dashboard bezel, and they show how to replace the OEM switch. There is a fog lamp switch relay in the main fuse box. I suspect the wiring is probably already intact and you just need to install the switch and lights. However if you're installing LED lamps then there is more to it.
@@spelunkerd ohh... ok. So, their's whole nother switch. Crazy... no existing wires. Running all wires or yank it from a parts yard. I mean... not that hard to wire a relay. But I'm going to wire it through the fuse box.
Spelunkerd I bought a new injector but when I got home I decided to switch cyl5 with cyl1 hoping the misfire would follow the injector, but to no avail P0305 oh yeah on a cold start Truck has rough idle then after a few seconds it goes away. I feel like that guy in the Comercial where his car is a big baby!
Good question. This truck has had a subtle misfire for years, on and off. At times it improved with fuel injector cleaning, and at one point it improved for a while when I changed plugs and wires (video done). I never did replace the plenum pan, and although I actually got the Hughes kit, it is still sitting in the garage, waiting for the day I have the intake off. More recently about 4 years ago I did a series on the Picoscope laptop oscilloscope, and to my surprise I found an abnormality on cylinder 4 that I traced back to a defective, fairly new plug! It made for an interesting video, the first on the Picoscope playlist on my channel. If you look closely at the plug you'll see there is a defect in one of the electrodes, it almost touches the other side. Changing the plug solved that problem. Early this year I noticed the abrupt onset of a dead miss, and I went straight to the labscope to nail it down as an open plug wire contact where the wire was attached to metal prongs of the plug terminal. The voltage on that wire was through the roof compared to all the other wires, and at the defect there was black powder from the contents of the wire. I was too busy to video that one but it was another easy diagnosis with the right tool. The truck is still used almost every day to haul brush, dirt, and garden debris. Working great!
spelunkerd, how's it going, so I've got a 1999 dodge ram 5.9 v8 4x4, when I check the oil with a cold engine it says zero, when I check it with the engine warmed up it says over the max amount.the oil pressure is at 40, I use mobel 1 10w30. it has been recently idling funny when in park it wants to shut off and has a small ping. I put seafoam into the gas and and the engine about 2 weeks ago could the seafoam have caused a problem? or what could the problem be?
I noticed when I openned the throttle body on my 5.s Magnum there is considerable oil on the Plenum pan, I had to replace both the Breather element and PCV valves recently. The oil does n't contain a sweet smell cold or hot and the engine stalls at about 130 when not level. any thought?
Yes, a vacuum leak typically has a dramatic effect on idle speed, usually increased in a bumpy kind of way. When the throttle butterfly opens, there isn't much vacuum to draw unmetered crankcase air into the intake, so on live data you usually see lean conditions improve at wide open throttle. That's the classic way to spot any vacuum leak, it differentiates it from other diagnoses such as fuel delivery problems (MAF in some vehicles) etc. That said, with a big plenum leak you get more oil drawn into the intake so it may be more complicated (oil consumption, black exhaust, sometimes poor acceleration). Since that oil can sit inside the intake, the association with throttle position is not so clear. In old vehicles the challenge is to differentiate that from more serious problems like leaking rings, poor compression, valve issues, leaking PCV valve, etc.
Well, on this engine, a misfire, pinging under load, and oil usage almost always lead you to a blown plenum gasket. I have recently found, from experience, that if allowed to go too long, the blown plenum gasket could be possible cause of head gasket failure. If this is true, is it possible this is because the oil enters the combustion chamber as a liquid, causing excess pressures inside?
I don't have detectable vacuume in th crank case but lookin down through th throttle body you can see a lotta oil on th bottom of th intake an thier oil residue on th bottom side of th throttle plates. Engine smokes pretty bad when it's been sittin a while it don't immediately go away but it does after you drive it a while
Have a look at the PCV valve to be sure it is not stuck open, these should rattle when you shake them. Overfilling with oil could be a factor, many of these have oil in the plenum normally, so it's a tricky question if vacuum is normal. Typically a leaking plenum gives other problems, and many of this generation are already fixed at some point. Replacement plenum pans are nonmagnetic, and the OEM pan is steel, so you can tell easily with a magnet.
@@spelunkerd yea it's got 173000 miles on it and I believe it had the original PCV valve on or it had been on it for years and it was stuck. Hose from it over to th manifold had a lotta oil in it and a lotta oil in th manifold. I changed th PCV valve and hose and with it runnin at a high idle sprayed a lotta air intake cleaner down th throttle body and took it out on th interstate and ran it about 60 mph for about 10 miles. It's quit smokein but when you look down through th throttle body you can still see a little bit of oil but not like it was. I guess il run it for a while and see how much it's usein. This is th 2nd 01 dodge iv owned and this is th first iv heard of em doin that. I just wonder how many people have put engines in them trucks couse they didn't know about that thing. All an all tho that 2nd Gen dodge is rugged dam truck
The Gen 2 Dodge Ram had this problem, these vehicles are almost 20 years old now. Mine was a '98, and most were within a few years of that date. When it was discovered, Dodge modified their procedures to correct the defect, which came from differential expansion of aluminum compared to steel as the engine heated up.
hi, i have a 1994 318 magnum on a jeep. i did your test, got no vacuum, but only got about 0.5 psi positive prssure. looking inside the the plenum i see usual oil spatter but no pools. oil loss is half qt per 5000mi, have no blue smoke, typically bad 318 mileage 12-18 mpg lol. a little pinging climbing 7 % grade but goes away with the OD turned off. the slight oil loss seems from leaky valve cover gaskets. i wonder if thats why i cant get the positive crankcase pressures you get? ps thanks for the video.
There are lots of variables as far as crankcase pressure, air can also escape through the dipstick, too. I would dismiss the minor variance between mine and yours. This plenum pan gasket problem was an issue with my specific vintage of truck, but I don't believe the older trucks like the '94 were especially prone to it. The main problem was the way some parts were aluminum, some steel, and with the difference in thermal expansion coefficient, they saw problems that were only rarely seen in older all-steel trucks. There were major design changes in about 1997-8. I'd have a look at your PCV valve, make sure it rattles when you shake it. I wish my mileage was as good as yours, ha ha!
@@spelunkerd hi, replaced the pcv and the rubber grommet last summer. but just discovered my latest vacuum leak; its a faulty EGR solenoid leaking and also the egr valve never opens. they last maybe 2-3 years from my experience. so now my gas mileage may go up from 12 to 12.5 haha. thanks for your feedback, keep up the good work
I did a similar test, but with just holding my finger over the pcv vlave, and otehr end blocked too, like you I could not detect vacuum but pressure. So I'm looking elsewhere on where 3 quarts of oil went on the last tank of fuel, no smoke I can see. Its keeps blowing O2 sensors tooo, getting tired of it. Thanks for the video.
You might start with a compression test. I wouldn't discount the idea it's the intake gasket, and if other things fit and if the engine seems good you might go ahead anyway. Any test will have false negatives.... If it does turn out to be the plenum pan gasket, please stop by so others will hear your full story.
2002 ram 1500 5.9 error code po 300,303,305 off and on with rough idle? Changed wires,plugs, cap.rotor, All had to be done anyway.Ran a bit better but rough idle and misfire seem to be an issue.
Lots of things can do that, and investigation of some may require more specialized equipment than you have access to. I'd probably start with a compression test, and if that's good I'd check the battery and look for a vacuum leak. I'd also double check your wire routing and contacts, since it would be very easy to mess that up on this engine. Yeah, the look at crankcase pressure might show something with this particular engine. If all that's OK I'd check fuel pressure and maybe consider putting a labscope on, to search for more clues. I would avoid replacing any more parts until you have definite evidence of what is wrong. All told, unless you feel comfortable doing all that it would be wise to ask a pro to help you out. Diagnostics is an underpaid service and it may help you to avoid very expensive mistakes.
I have a 1996 Dakota sport 5.2 4x4 5spd short bed. I bought 7 months ago, on trip home I averaged 17.3 mpg. I added shorty headers and flow master 40 muffler and I averaged 19.73 mpg. I bought the Hughes airgap manifold since everyone was Gaga about it. My mileage now is barely 14 driving gramma speed. What gives? With stock manifold I could drive it hard..80mph consistently and get hair shy of 20. Now I can't get over 14. It revs quick and easy but figure my vacuum leak is better. I'm gonna yank off and throw the $600 manifold in trash and go back to stock.
The Hughes plenum repair fixed a vacuum leak, which is mostly a problem at idle when the engine is not driving the vehicle forward. By definition, any fuel consumed at idle is therefore wasted energy, so the engineers designed the engine to run at an idle rpm as low as possible. After the repair, vacuum at idle typically increases. Increased vacuum at idle draws in more air, which will be detected by the upstream oxygen sensor, in turn sending a transient lean signal to the PCM. When it detects a lean signal from the oxygen sensor, the PCM is programmed to react and deliver more fuel from the fuel injectors to regain balance of the combustion products. So, I would expect more fuel consumption after a Hughes repair when the car is not moving. Indeed, many people who have done the repair complain that fuel mileage is not improved. Of course the story is a little more complex since the faster idle rate would trigger the iac valve to close down and then slow idle rpm to spec values. Also the PCV valve delivery volume fluctuates depending on how much vacuum is present. With all that complexity, the practical observation about fuel consumption has to go back to what people see. Almost nobody says fuel mileage is improved after the plenum pan repair. If you go back to a stock intake, I wouldn't be surprised if your fuel consumption does not improve, since you probably had a manifold leak before the new intake was put on. Good luck!
I had a 97 Dodge Ram 1500, 5.9. 215xxx. I've noticed a ticking noise when I accelerate. I'm thinking it's a manifold leak. So I'm asking is a failed platinum gasket could cause that has well? I believe another way to tell if it's blown to take the air filter off and see if there's oil sitting down there.
+Willie Gusa There is normally a small amount of oil at the base of the intake manifold, coming from aerosol oil that makes it's way through the PCV valve. You should have a demonstrable vac leak and measurable oil consumption before considering a manifold gasket leak. Ticking has not been a big feature, and in fact the throttle butterfly is wide open during acceleration so vacuum leak issues like the plenum pan gasket failure are generally reduced with increasing throttle.
I have a 99 Ram 5.2L with a popping coming from the throttlebody while under load -i.e. pulling a hill in OD or under heavy acceleration. My fuel economy is around 12 so I believe it could do better. I have replaced the upstream O2 and downstream O2 sensors. The truck has around 180K. What could I check to further diagnose this issue?
A bad pan gasket could certainly cause what you describe. Are you using any oil? I would look for evidence of pan gasket failure first, unless the repair has already been done. If you are not sure, a magnet on a stick into the intake plenum may help. A lot of guys get 12 mpg with this generation of engines, especially if there are big tires or a lifted body.
Looks like I'm about to do this test. My truck is at 138k miles now. Symptoms/other details: I burn 2-3 quarts every 5-6k miles. Occasionally I get an intake backfire when snapping to WOT. Idling is ever so slightly rough. I do occasionally get pinging at cruising and WOT. Spark plugs look decent, and it never blows any oil smoke out the exhaust. Dry compression is 150-155psi in all cylinders, which is decent. Gas mileage is 12mpg city and 18mpg highway, this is on a 2WD 5.9L.
Hello Spelunkerd, Same as other intros.....I have a 99 SLT Laramie 5.9 with a boatload of miles on her! I have changed, replaced, and added numerous mods to the truck throughout the years. If i can't fix it, I send it a local shop. Now the question I have for you is: My truck runs great, idles fine, and has no issues other than this one I cannot figure out........it chugs hard between 40 -45 mph. It accelerates fine up to that speed and rides well after going beyond 45, just an added not. I have a new tranny, new exhaust system, use 10-40 Mobil 1 Syn, and tons of other stuff. I need your input as to what you may think the issue is. An idea is more than enough. I was thinking a new distributor cap, coil, wires, and plugs should do, but I'm asking you before I do something that I don't need to do. Thanks for your advice.
+wannabeangler Sounds like a transmission shift timing issue. Perhaps RPM's are too low at that speed to get much torque from your engine. You get better fuel consumption at low RPM, but less torque for sudden acceleration. I don't know if that can be reprogrammed but there is an overdrive switch on the end of the shift lever which can be pressed to change the shift pattern. Of course you can shift manually, too, though that can be annoying. With such an isolated issue at certain rpm, I doubt general efforts would have much effect.
I have an 04 ram 1500 3.7 and it's burning oil. No smoke out of the tail pipe but I can smell it when I'm standing in front of the engine. It's not burning at an alarming rate but I do have to add oil in between oil changes. Also, there seems to be moisture getting in there because when I pulled off the cap, there was some milky beige foam on it. It runs fine, doesn't smoke or make strange noises. Any idea?
Could be a head gasket or bad rings, maybe a coolant lead somewhere. I'd start with a compression test, look for codes, check for exhaust byproducts in the coolant system. Milky oil is usually an ominous sign, although once before I found it with a simple coolant leak and secondary overheating. A much more common cause is a bad head gasket.
Excellent video, thanks! I looked in my 5.2 Durango intake. Is this Hughes plate cast aluminum? What about the stock sheetmetal it's steel? The one in mine looked pebbely like cast aluminum, possibly mine has been done already....
I know its late, but stick a magnet down the throttle and see if it sticks. If it does, its a stock plate, which may have had the gasket repaired at the stealership but blew again, thats what they do. If it doesnt stick, then it has an aftermarket aluminum plate in it. Hughes wont look pebbly, it will look machined.
Spelunkerd, as a novice, I hope this isn't a silly comment, but your pressure test was performed with the hoses closed off with tape, providing a known consistent environment. Is it possible that the idle problems you experience once the original equipment is back in place points to a failure of the PCV valve or other connected original equipment hoses/devices?
+Scott Jenkins That's a good point. When I looked at the PCV valve it was working fine, with a nice rattle and normal flow on simple bench testing. Even then I replaced the PCV simply because it was 14 years old, and I thought about making another video. Never got done, ha ha. Thanks for watching!
Working with my mechanic: my dodge, 4x4, 230K miles, acts like it is missing when starting off from stop or idle then goes away after 25+ mph, although had a few backfires running downtime highway 60 -70 mph. Scanner shows P0300, wa first suspecting O2 sensors in breather or at catalytic conv. But Mechanic is suspecting leak around intake gasket as spraying combustable fluid along gasket in back causes engine to try and die. He has replaced plenum gaskets before, especially Fords, stuff getting cheaper all the time. His guess is to replace gasket and hope plastic plenum still fits tight, if not go back do plenum as well. Maybe both at same time. Between makers, all a little different design. Anyone thoughts????
What year? If you spray water on an intake leak the RPM will fall, if you spray combustible fluid right on the air leak it will rise (opposite to what you describe above, did you get it backwards?). Even by itself that is a very powerful finding, so if it was definite as I describe above then the diagnosis seems pretty clear. I agree, the symptoms and a decreased RPM with water are suggestive of a vacuum leak, and more evidence to support that would include positive fuel trim on live data that normalizes when RPM increases. If the findings were not clearly convincing I would verify them on a scan tool, in part because other things (like a stuck open EGR valve, etc) can present in the same way. Vacuum leaks tend to settle at faster RPM because the manifold vacuum is lower so the leak will improve. The test I did above was for a specific plenum pan leak where air is getting in from the crankcase, not from the topside of the engine. A plenum pan leak by itself will show no change when spraying water or accelerant, since it is completely isolated from air above. That said, if your Dodge is of the vintage prone to pan leaks, and you have to go in anyway, it makes sense to replace the pan at the same time. In that MKII model I would use the Hughes kit, it's not that expensive and it's got a good track record for the plenum pan leak in my generation of vehicle. However if your intake is plastic then your truck is newer than this one, in which case it is likely not so prone to pan leaks into the crankcase. Plastic intakes are very prone to leaking over the years, and the story sounds typical. Good luck!
mine had failed, 98 ram 5.2 318 laramie ext cab, the model with no back suicide doors. i did a rebuild due to what i thought was a blown head gasket, i had water coming from exhaust..truck idled perfect, it ran perfect no misfires that u could see by running it or idling, had power i could burn the tires and never stall, well headgasket was warped just enough to allow leak, i had the number 8 misfire weve all been warned about.. but my plenum gasket was damn near completely gone. i didnt expect it and was luckily planning on changing it and already got it lol. it was so thin and wore away. id say 30% of gasket material was left..40% at best and thats pushing it..i have some dragster buddies who love buying old cars rebuilding them they race them till there sick of them then do it all over again, they helped me and they couldnt believe how good my truck ran at the time 250k miles, bad head gasket, it took 10-15m to overheat, almost no plenum gasket, oil pan gasket and valve cover gaskets, throttle body gasket gone, i had oil on the plugs, water pump had sheared some propeller fins off too you couldnt tell till disassembled. and untold ammounts of sludge builtup, mustve used 30 cans of carb cleaner..if it hadnt been over heating u wouldve said the truck ran perfect lol it was incredible.. i love the truck i still have it after 10 yrs ive had many vehicles come and go but not it..its my toy, my best friend, my one true love lol and it earned that, it wasnt an immediate thing
im getting the number 8 misfire it doesn't do it all the time but when it does truck almost dies at idle rough as hell then it throws the code and if i turn it off and on again runs fine sometimes for days sometimes for a Minuit what causes the number 8 misfire
GREAT VIDEO, IFOUND VACCUM IN MY CRANKCASE AND ORDERED A HUGHS PLENUM REPAIR KIT. BOUGHT A VACCUM AND PRESSURE GUAGE FROM HARBOUR FREIGHT FOR 15..DOLLARS TO TEST PLENUM
Hey, thanks for the feedback! Although I can understand false negatives with this test, I think a false positive like this would be VERY unlikely. Please let us know how it worked out.
I have a 96 ram 1500 5.9L (gas) 150,000 miles and sometimes it has lack of power and second was a 50 mm holy throttle body stock cause my truck had one when i got it
I have a 2001 Ram 1500 Quad cab 4x4 w/ the 5.2. I have done the test about 3 times, I think. And every time i have done it, i get no indication of vacuum where it shouldnt be, ie, it "passes". I too wonder if i am getting a false negative. It has +260k miles on rhe clock, it seems to idle fine to me, just an occasional flutter that I expect older vehicles to have, I hear a hiss, like a vacuum or intake leak that i cant seem to pinpoint, oil use seems high to me even for a high milage vehicle, gas milage sux even for a Dodge halfton, and it pings under load. I am stumped as the symptoms point to the plenum gasket but the test says look elsewhere.
If you hear clear hissing, the story is pretty typical of a vacuum leak, somewhere. A smoke test of the intake would quickly diagnose a vacuum leak, and if you get smoke coming out the oil fill port or dipstick tube, the leak would be internal through the plenum pan. I suppose you could do that with a cigar if you don't have access to a smoke machine. Remove the air filter housing, and clamp the PCV hose, put a plastic bag held tight by an elastic band over the throttle body intake, blow smoke into a vacuum hose and watch to see where the smoke appears. You may find one you can rent. There are many videos showing how to make a smoke machine, and Ebay has one for sale that is said to work fine (search Stinger smoke machine on Ebay, I have no personal experience with that one). Another option would be to ask a pro to verify the diagnosis, I don't think it would cost more than an hour of shop time to get a diagnosis, which you could then fix yourself. They would be able to use a pro level scanner which might help to verify a vacuum leak by looking at fuel trim patterns. Interestingly, poor fuel mileage is not typical of Dodge plenum pan leaks, so don't expect fuel economy to improve. It's bad in all of these trucks, we learn to live with it. The last time I had a fishbite miss at idle, it was a bad plug, which I found when doing secondary ignition analysis with a labscope. One common area for a vacuum leak in the Ram is the MAP sensor vacuum tube that is concealed under the MAP sensor. Don't forget to look for misplaced vacuum hoses, it would be a goofy thing to forget. The other area air can make noise is where the air filter housing rests on the throttle body, it sometimes can go on cockeyed and give a leak there. However since that is outside the throttle butterfly you don't get vacuum leak fuel trims, it just makes noise. With high oil consumption another option would be to do a compression test in an effort to decide whether more aggressive procedures are worth while. If compression is poor, you may save money by doing that kind of testing up front.
I tested my vacuum just basic test no blocking off anything but its about 10- 21 then warmed up drops to about 8 to 10. how weird is that? whats your thought s on it?
At idle, 8-10 is too low -- time to look for a vac leak. If the rest of the test passes, I would consider a smoke test if you can't find an obvious leak. With warming, the leak is evidently larger, wherever it might be. The stock plenum pan is made of different material than the block, with a big part of the pan defect being differential expansion under heat. But that could happen in other areas, too.
update> i was wrong about the vacuum. im pulling 15 to 17 inches of vacuum once warmed up. its steady but moves back and fourth. I"m thinking either throttle body gasket and/or intake. what do you think?
Hello. 06 Commander 5.7l with coolant leaking into #4 cylinder. Both spark plug electrodes in #4 were detached from plug and throwing an 0304 code. Replaced both plugs and now that I have spark in that cylinder im getting white smoke from tailpipe. Crankcase oil is clean. Do you think plenum is bad? Or maybe plenum gaskets? Engine cranks normally with no symptoms of hydrolock in a cylinder.Thanks
Head gasket leak, a bad plenum pan gasket by itself won't do it. You could check for exhaust gas inside the cooling system, but the story sounds convincing even without that. Good luck!
@@spelunkerd Thanks for weighing in. Had a 3.8 GM engine that had identical issue. Coolant passage in plastic plenum was breached. It was a bad design. Had all the symptoms of a bad head gasket but was the plenum. Thanks
I've got positive pressure as you did but do see some oil in the intake through the throttle body and get a ton of blue smoke under load and after revved
Before going too far I'd do a compression test to look for bad rings as a cause. If you've got a bad cylinder there is not a lot of reason to go further. If compression is consistently good in all cylinders, I suppose it could be a plenum pan issue, though it is a little unusual not to see vacuum in the crankcase if it is leaking so bad as to cause blue smoke. Make sure the PCV valve is working, that would be a goofy cause if overfilled with oil. The other thing that can cause blue smoke is leaking tappet seals, though that problem is almost always at startup only.
Dave, I just thought of something else that might be beneficial to you if you decide to pursue doing a plenum pan repair. Once the intake manifold assembly is reinstalled, go ahead and reattach all of the cooling system components(miles well change the thermostat(180F or 195F) while you're there, also the bypass hose. Fill the cooling system with enough ethylene glycol coolant so that you can do a pressure check of the system with a pressure tester. I would do this before reinstallation of the accessory drive bracket, alternator, ac compressor, etc. I would rather know if there is a leak now, than have to tear it all apart again. The factory cylinder heads are known to crack, especially close to where the intake manifold meets the head. Being preventative never hurt anyone. Your name is Dave right? HaHa
That's a good thought. I've seen guys do that, usually when they replace a head gasket and find no abnormality of the old gasket. Then they start to sweat over whether the block or head might have a hairline crack. Lately my truck has been running great, so the plenum pan is going to wait....
Hello spelunkerd, I have a 99 5.2. don't much lately but it just started smoking blue at startup and then turns white, Allot of smoke. I know its not the Trans fluid, Pressure builds fast in the cooling system. The change of color confuses me a bit. Have not tested compression yet. Never had any issue with the truck always ran great. Let me know what you think .Thank You.
+Golfingferdie That sounds like coolant is making it's way into a combustion chamber. The commonest place for such a leak to occur is at the head gasket, and such a leak is usually two-way, with combustion gasses also making their way back into the cooling system. Such gasses are most easily detected with a tester you can get at a parts store, and some stores will allow you to borrow the tool. You simply allow the engine to cool, then safely remove the radiator cap, and test the gas inside the radiator. If the liquid in the tester turns color (to yellow), you've got a leak. Finding it usually involves removing the head, a big job. Good luck!
Thank You for the response. I am not looking forward it. I have completed this before with other vehicles that seamed much easy just by the number of things removed.. Again Thank You.
spelunkerd, how's it going, so I've got a 1999 dodge ram 5.9 v8 4x4, when I check the oil with a cold engine it says zero, when I check it with the engine warmed up it says over the max amount.the oil pressure is at 40, I use mobel 1 10w30. it has been recently idling funny when in park it wants to shut off and has a small ping. I put seafoam into the gas and and the engine about 2 weeks ago could the seafoam have caused a problem? or what could the problem be?
+Stevo Nichols Hi Steve. I've never seen that before, although trans oil can show opposite findings when comparing running level to cold. I'd check the PCV valve, look for a vacuum leak and probably check compression to look for huge blowby. It would be wise to change out the oil and filter right away, and drain any seafoam that might be diluting the oil. I'd be checking if you've ever had the plenum pan replaced (replacement pan is nonmagnetic aluminum which is accessed through the throttle body). The most trustworthy readings are with engine cold, which is concerning.... Briansmobile1 did a recent video of an ATV which had a similar complex problem of fuel diluting oil -- watch his video.
+Stevo Nichols That's really odd. I might would have said that the oil drains in the cylinder heads could be clogged. That would mean that your results should be opposite, tho. Did you ever find out what the issue was?
You're likely using synthetic oil in a newer vehicle, and they tend to have higher consumption since they more easily pass by rings into the combustion chamber. There are not a lot of other places the oil could be going without finding evidence elsewhere.
I've got a 96 dodge ram with a V6 and rough idle. Saw your video and its interesting. I believe a small vacuum leak may not show up in a high mileage engine with some blow-by. The smoke machine may work if you take the rockers off in order to close all the valves, so you can build a little smoke pressure. Even with that, the smoke has got to make it out of the crank case. A bad IAC to produce and unacceptable idle. been there and replaced it and it fixed the really bad idle, but not the rough idle. I've replaced all the injectors too.
Ignition problems are fairly common with these trucks. In my videos on the Picoscope I show how a labscope can uncover a problem with a plug, wire, distributor, or coil. Make sure your wire routing is correct, there is a TSB out on the Gen II Rams of that era describing how even a slight variance in wire routing can cause issues. A relative compression test might show something, too. Worth a look....
I have a 98 Dodge 1500 with the 5.2 engine using about 1 quart of oil every 2 to 3 weeks, engine pinging and about 10mpg so I am thinking that I might have the plenum gasket leak. I saw the aluminum plate solution and the intake manifold swap solution but I am wondering if a regular performance intake manifold would also cure the solution instead of the other options? I cannot do the work myself due to many reasons and was thinking that the performance intake swap would be easy and fast for a shop to do, what do you think? Thanks.
Not sure. As I've gotten older I've strayed away from performance engine modifications. If I clearly diagnosed a bad plenum pan gasket I would fix that alone. In your case you need to verify that the oil loss isn't something more serious (like worn rings), so I'd do a compression test first before investing much in the engine.
The Hughes Airgap is a great option and has proven results. That's all I can think of that's readily available and pretty much bolt-on though. Both of the M1 intakes are still on backorder indefinitely and hard to find. Replacing the plenum gasket isn't too difficult, heck, making your own plenum plate isn't hard either. Grab some 1/8in aluminum, cut, and drill.
I bought the Hughes plate, plugs, wires, cap, rotor and thermostat. I paid a mechanic to do the work but I ended up helping to get it done faster. The plenum gasket was gone in 2 places. Once everything was back together the parts made a big difference, I am very glad that I did it. I ask other mechanics if they have heard about this issue, most have not heard about it but some have. Between changing out everything it took about 6 hours more or less. If I ever buy another Dodge truck with the 5.2 or 5.9 engine I will have this done to it just in case. No more oil burning at all now. Thanks for the information.
I had a similar issue where I thought my plenum pan had failed. I was getting rough idle and sometimes a complete stall. I have a manual transmission and whenever I would push in the clutch to the floor the rpms would fall below normal idle and stall out unless I tap the gas while its falling to prevent the stall. I later realized the cause of this was not the plenum after replacing it with the hughes fix kit. The actual cause was a failed egr valve that was stuck open.
Diagnosis is always the most challenging part of auto repair, sometimes difficult even for guys who do it every day. I get the feeling that pan gasket troubles got blamed for many issues through the years, though objective testing often failed to confirm the air leak. A sticking open EGR valve is one of those things that often doesn't come to mind, thanks for your contribution to the thread!
Any advice would be greatly appreciated. 2002 ram 1500 5.9 360. 141,000 miles. cylinder 5 misfire. Truck did have simptoms of misfire while in idle. Replaced all ignition parts. New plugs, wires, cap, rotor, and coil. Truck ran fine and next day cylinder 5 misfire again engine was misfiring. Took to mechanic that was recommended by friend he checked fuel pressure, injectors those were fine. He also checked compression on cylinder 5 he said it was kind of low 130 he said it should be around 160. He said most likely it needs a valve job. I need to fix this but I can't just do a valve job don't have money to spend what if that's not the problem I guess I just need proof. I'm just trying to see if anyone has had this problem all suggestions are welcome and appreciated and thanks.
You will get more attention at a forum, such as one of the dodge specific forums. One of my favourites is Ericthecarguydotcom. I would be putting the vehicle on a labscope, to try and better define what's going on in that cylinder. Leaking rings require a mechanical solution but it might be reasonable to try a higher weight, natural oil. Good luck!
RBTURBINA1 the proof is right in front of you. You already replaced everything else and you have low compression. Did you check compression in at least another cylinder or two? I've heard of Compression being as high as 245, but that can have to do w the gauge being off on the tester too. Also if your battery is getting low from testing all these cylinders at least 5 cranks that will give lower readings. Or if the throttle isn't opened all the way when you test. Also maybe overkill but did you check your spark plug gap? #5 could of got pinched closely together. You could do a leak down test. easy, look it up. That will help give proof that compression is getting past the cylinder walls via bad piston ring, or scaring of the walls. Also if any debris got in the spark plug hole that could cause the scaring of the cylinder walls, thus why it was working fine, then the next day it isn't. :( because you fixed the original problem, but created a bigger problem in the process by rushing and cutting seemingly minor corners...
RBTURBINA1 one more thing, if your valve seals are in their early stages of falling apart(just rubber seals) then you can use a oil leak stopper to swell the seals. (basically just salt from what I hear, but don't hold me to it) That is only a temporary fix, and I am Leary of mechanics in a bottle and the whole psychology behind the concept of their existence. Usually poor people(middle to low class, me included) buy them that already have car problems. poor people can't afford attorneys or generally have the time and knowhow to fight if the product totally destroys or makes their vehicle worse and they have more pressing issues like they are out of a vehicle and just too many little daily battles to survive, let alone take on a corrupt big business and there is the fact that the car was breaking down and maybe it getting worse had nothing to do with the product. If I was a POS I would market some products like that too, but I know the struggle and don't want to add to it.
I have a problem with my 97 Dakota sport 3.9 2wd 5spd. It idles a little bit low sometimes (650rpm), and will eventually show the check gauges light and the oil pressure drops to 0. This always occurs at a stop. As soon as you give it some gas it is fine again. I run 10w30 synthetic blend oil. It goes through a quart of oil every 200 miles but doesn't leak. I also only get about 200-240 miles to a tank of gas (mixed highway/city). I checked and cleaned the pcv valve and it rattles nice, it was a little gummy but not bad. Nothing improved. It runs and drives as well as can be expected for the mileage and I have put a lot of money into the truck and would like to keep it going. Do you think this is the intake manifold gasket? Also, I have read something about a "belly pan gasket" is that the same thing, or something different? Also, I am not getting any blue smoke. It has a little misfire every now and then usually between 2nd and 3rd gear or when the RPMs are dropping after shifting to neutral from 45+ mph. Sometimes when engine braking is will give a little backfire pop also. My passenger side exhaust manifold flange is shot to it has a pretty severe exhaust leak, not sure if this could be the reason I hear the pops or if it is another symptom of my oil burning / poor gas mileage problem? Any hints, tips or suggestions of what I should look at? Thanks in advance! Love your channel btw :)
+Nathan Ryan Since the oil pump is driven by engine rotation it's not rare for the oil pressure light to come on with low rpm. I've sometimes wondered if synthetic oil might make that worse because it has slightly lower viscosity, especially when cold. ie when peripheral resistance falls from less viscous oil, pressure will fall as well. However in your case clearly the issue is the low idle speed, and fixing that will resolve most problems. The two commonest causes of low idle are a bad or dirty IAC valve or a vacuum leak. In your case you have an engine that is prone to vac leak through the plenum pan, and you already have oil consumption. While cleaning the IAC and throttle body I would have a look at the plenum pan and put a magnet on it to see if it has already been repaired (OEM pan is steel, Hughes replacement usually aluminum). Also I would do the Chrysler authorized test for vacuum in the crankcase that I showed in another video, although I don't believe the test is completely reliable. Certainly if there is vacuum in the crankcase you need a new pan gasket, but any source of vacuum leak could present in the same way. In an older vehicle like this I would also do a compression test in case your oil consumption may be from bad rings, in which case you have bigger issues. Good luck!
Thank you so much for the fast and thoughtful response :) I will give the IAC and throttle body a good cleaning today and try the magnet test you suggested. I'm willing to bet it is the stock one though. As a temporary fix until I hunt down the actual source of the oil burning do you think maybe I should throw in a quart or 2 of some 20w50 or maybe some Lucas oil stabilizer to thicken things up a bit and see if that helps? And as for the compression test, if I do a dry run to get readings and then do it again with a little oil in the cylinders and the pressure goes up it means the rings are bad right?
+Nathan Ryan I would probably just switch to natural oil at the next oil change. Yes oil in the cylinder will usually increase compression if the leak is from bad rings.
Your PCV system is arranged opposite of mine. I have a hose coming from the left valve cover gasket in to the top of the air box, and on the right I have a hose coming from the valve cover gasket into the side of the intake manifold. My truck is a 2001 but I've had a 99 in the past that was the same as mine. I wonder why the difference on the 98? I'm going to do this test soon and regardless of the result I am installing a Hughes-Edelbrock MPI Air Gap manifold in place of the stock kegger. I still haven't tracked down the rough idle but I would be surprised if the plenum gasket is intact. I also intend to test the 02's and probably will replace the cat on general principle. I have read that the stock catalyst on these trucks is especially restrictive and I am told that an aftermarket high-flow unit is worth a couple miles per gallon.
That's worth exploring, and videorecording your effort. Lots of people are interested in these trucks -- they seem to be a favorite for people who like to tinker with their vehicles. I would certainly be interested in what you do. That's interesting to see the difference between yours and mine. I don't think it makes a big difference, since the block is mostly symmetrical. But for the test you need to be sure of which one you use to measure manifold vacuum -- one connects above the throttle butterfly, one below.
spelunkerd I learned to drive in the '99 with 265k miles on the clock so the 2nd gen body style Rams will always be special to me. It's a big plus that even if they aren't running properly they seem to keep going. The only downside to them in my opinion is the fuel economy, but it's a truck and you should know what you're getting yourself into if you buy one these days. I'll admit I am intimidated by the intake swap because it's the largest repair I'll have done myself up to this point. The truck is my secondary vehicle so the amount of time that it takes me is not too much of an issue, I'm just worried that I'll mess it up somehow. I intend to complement the new intake with a TB+IAC cleaning, a new filter setup, and a complete ignition tune-up as well. I've never really made a video before but if I can find a place to put my phone such as it will record what I'm doing, I'll try it out. I expect to do the repair in less than a month's time. Only thing holding me back right now is the expense of the intake.
The breather tube is a direct port to the inside of the left side rocker cover, and air pressures there are the same as air pressures in the crankcase. I unhooked the breather tube from the air filter housing and attached my vacuum gauge to that hose. See the description at 3:40 of the video.
Yes, I think the dipstick tube would work, but I chose to do this exactly as described by Chrysler as a corporate guideline for their OEM mechanics.
Other, older designs may not leak internally....
Spark knock/Detonation results from incomplete combustion. Once the spark plug is oil fouled and no longer firing, essentially you have oil and fuel exposed to compression pressures. The heat alone will bake the oil, causing build up on the piston. This contributes to raising the overall compression ratio of that cylinder. Because CR has been raised, cylinder temperature is also considered excessive. The heat alone can pre-ignite the fuel long before TDC. With old spark plugs, these increases in pressure/temperature can and will crack the porcelain, which now leads to a compression leak. I've seen plug wires blow right off of a faulty SP. I have also seen heavily corroded plug wires(spark plug porcelain was leaking compression, moisture being a byproduct of combustion contaminated the plug boot) When this plenum pan gasket fails, it will certainly misfire because it is burning oil, but it won't be burning oil from spark ignition for long because the SP will become fouled. Thank you for taking the time to educate the general public, this field is too diluted with ignorance and the only way we can eliminate it is to educate others and of course have fun learning at the same time.
What a brilliant description of the ugly cascade that happens when the pan gasket fails. Your explanation of the cause of spark knock is understandable and very believable. Thanks for recording it here, Jarin!
Dave
thanks for the info. helped alot
I would remedy asap this design as it can plug CAT & will blow engine. Which exactly happen to my gen2.
Does anybody know why they even put that bolt on plate on th bottom of that intake. I aint never heard of a purpose for it
So on the test, you have attached the "engine vacuum tester" to the breather ? or to the crankcase ?
Thanks.
To measure manifold vacuum, I use any available hose that attaches to the intake manifold (the brake booster tubing was convenient). But that was not the test, it was just a demo to show what my plenum vacuum was doing.
Yes, when I did the test I did measure crankcase pressure by disconnecting the breather tube, but remember to disconnect and clamp off the tubing connecting the intake manifold to the crankcase. You want to be very careful to do this correctly since you normally have some vacuum in the crankcase, coming from the PCV tubing. If you don't properly obstruct that PCV pathway, you'll get a false positive.
This video has opened up a surprising debate as to how sensitive the test is. Official Chrysler documents say that there is no meaningful leak if the test is negative, but many armchair internet experts say the test is insensitive. I don't know if this is corporate denial or whether those people are wrong.
Hi Spelukered! Watching your videos and trying to diagnose my 02 ram 1500 5.9l 360..I am having an intermittent misfire on cylinder #7. Replaced tps, 02 sensors, spark plugs, plug wires.. It shakes hard on start up but will go away if you turn off the truck and turn it back on. Occasionally get code P0172.. Running rich. Any comments would be greatly appreciated.
This is tricky. The first thing I would do would be to put the secondary ignition on a labscope, and I uploaded a short video of that last week. If one injector is pissing fuel, that makes the bank 1 sensor 1 see rich, which makes the computer reduce fuel to all the cylinders on that bank, so all the other cylinders look lean on the scope. Or if it's a bad plug or wires, sometimes the scope pins that down easily, as I showed in the video. Unfortunately few of us backyard mechanics are lucky enough to have access to a scope. One of the things that is very poorly paid for professional technicians is diagnostic time, so one option would be to ask for advice from a pro, even if you end up doing the work yourself. It may save you money in the long run because you are less likely to play the game of replacing normal parts. Alternatively you could do a few simple tests, like hooking up a diagnostic scanner that is capable of live data to be sure both new O2 sensors are behaving normally, etc. In these older cars, sometimes it's nice to be sure there is no mechanical issue by doing a compression test first before you get into discussion about the costs of repair. Good luck!
You clever fox! Ty for the vid, I believe I can FINALLY get a conclusive yes or no today. Geez, I been beating my head against a wall for weeks....
Well im not losing oil,the engine runs smooth and steady for a 318 but I believe i have weak vacuum do to, under throttle the vents default to DEF and the 4x4 is sluggish to engage. I did do that gasket on my 97 with a 360 and it really wasn’t a bad job but obviously I don’t wanna “fix” something not broken
Just removed an 89 Ford Plenum. Still not sure, did not know of this test. The gasket even if not leaking was super hard, flat and brittle shattering to pieces so an improvement but probably would have been fine as long as not leaking. Even a new one can....I will do this test after putting in the new one and make sure. Thanks!
One last thing I could think of. You had mentioned that your idle was rough and you had a slight misfire at idle. I was wondering if your scanner offered misfire counters and if so, you could take a look at that. If not, possibly a power test on each cylinder.
That's good feedback, it's worth noting that any test has sensitivity issues. I was surprised to read in the Chrysler manuals that they are so dogmatic about the issue, at least on their official documents.
On my vehicle the power is still excellent and I've never had pinging. Really, it's running better than ever this year, even without a new plenum pan. I'm a little disappointed since I was looking forward to doing it.
I worked on a 2001 3.9L Dakota that had misfire on cylinders 2 & 6. I changed the spark plugs and got cylinder 2 cleared up. I sprayed brake parts cleaner onto intake where it contacts the head with engine running. As I sprayed the brake parts cleaner onto intake on cylinder 6, the engine surged. Ah Ha! Intake gasket was cracked there. So I took the intake off, went with the Hughes aluminum plate plenum kit, and replaced the intake gaskets. It runs like a dream now. I had about $300 in parts total with full tune-up by doing it all myself.
heyy i saw a vid you posted. had a part number for the intake filter box gasket. i cant find that vid. do you happen to know tht number or which vid that might've been? thanks man
I’m really hoping you can help me out on this, I have a 96 Dodge Ram 1500 5.9 and it idles at 1400 rpms and when it’s running and u pull the dipstick it’s sucks air into it and when u plug the hose to the air filter it idles down to 800 and when you plug the hose from the break booster it also idles down to 800 rpms. I replaced all my sensors and checked for vacuum leaks but I can’t find any and I replaced my throttle body gasket. Any ideas?
Vacuum leak, for sure. The brake booster improvement is interesting, since I wouldn't think a plenum pan gasket leak would cause a leak at the brake booster. Likewise I wouldn't think a brake booster leak would cause vacuum to appear at the oil fill tube, so you may have two separate problems. If you don't have a smoke machine, first check for a disconnected hose and do a careful inspection. A stuck open PCV valve can cause vacuum to leak into the crankcase, and replacing that is a lot easier than replacing the plenum pan, so I'd check your PCV valve first. Make sure it rattles, and I'd probably do the procedure shown in this video to formally test the plenum pan. Notice that when you block off the PCV valve during that test, you take the PCV valve out of the equation. Regarding the brake booster, those can certainly leak, but first check for a bad hose or bad connection. There are videos here on RUclips explaining how to approach a leaking brake booster. Good luck!
Thanks for the informative, technical and concise video! I suspected a slight leak in my plenum (an '01 magnum 5.9) but for about $17 for a Harbor Freight gauge I confirmed no leak, similar to your test. Saves me a long weekend of replacing the gasket on a suspicion! I'm now considering a DIY smoke machine to look for other small vacuum leaks.
I've heard some guys say that a small plenum leak can paradoxically improve gas mileage, which when fixed worsens as the vehicle is able to achieve that magical 14.7:1 ratio. They make the point that the target of optimizing fuel ratio is to reduce emissions, with fuel economy being only a secondary goal. If the air fuel ratio is a little lean, the car has slightly better gas mileage but more emissions. Those reflash programs designed to improve gas mileage alter the target fuel ratios.
Yeah, you would be right more often than not. But in my case I have no oil usage and no pinging or performance difficulty. I have only poor gas mileage and slight variable intermittent shudder at idle. I was thinking the same as you, with the notion that fixing it early might reduce the chance of secondary damage if I caught it early. I"m still ready to do the plenum but I've paused for a bit to consider my options. Thank you for looking this over, I value your thoughts.
I had another look at the stepper motor counts on the IAC yesterday, Terry. Idle IAC counts after a long warm-up were almost at target at 50. However I like your theory about a small leak, and I'm making preparation to build a small smoke machine to look at that possibility more closely. Thank you for your ongoing input.
Dave
Dave, one other thing and I'm sure you already know this. When you do your smoke test, make sure the engine is cold. When I'm doing smoke tests especially on the intake area, I like the engine to be cold. The reason is that when the engine is warmed up, sometimes the intake gasket can seal itself and hide small leaks. I'm looking forward to your next video and good luck.
It was the one where I cleaned the IAC motor and throttle body. I actually made my own out of cork one day, but given that the factory gasket is only a couple of dollars it doesn't make much sense to make your own. You don't necessarily need a tight fit there because above the throttle body a slight air leak doesn't count as a vacuum leak, and there's no MAF sensor. Below the butterfly valve is another story.
No sweat, Richard, thanks again for watching.
Thanks for your response. It's an intermittent shudder at low rpm only, and I called it a misfire. However I have new software now (autoenginuity) and the misfire counter is not recording it. It's been going on for a long time, years, with no worsening except the fall of in gas mileage. What do you think about my borderline vacuum at idle, better at 2500 rpm? I think I'll do a smoke test to try and find a small vac leak, and I think I'll change out the PCV in case it isn't closing completely.
Thanks for looking this over, Terry. What I described as a misfire is more accurately described as a slight 'shudder' at idle, like it's about to stall. On the scanner misfire count is 0, and to be honest I'm not sure how to interpret the IAC counts. You're right, at idle the vacuum is on the low side, and I did try some carb spray looking for a vacuum leak and I didn't find one. I was a little surprised that vacuum at 650 rpm was 17 and at 2500 rpm it was 22 - maybe a small external leak?
Yes, possible. Rear main seals commonly leak on these vehicles, too. But leakage alone isn't causing your pinging or loss of power. My rear main leaks a little and I'm just watching it, since repair of a rear main is a big job.
A compression tester is fairly inexpensive at Harbor freight or Princess Auto.
Excellent video. I performed your test and I definitely need to change the plenum gasket. I have pinging, excessive oil use and very poor gas mileage. I'll let you know how I make out.
Thanks for the feedback! Please stop by and let us know how your repair worked.
I have the same thing going with my truck I too will be checking my gasket I also have two vacuum leaks a big one and a small one this may be one of them
I'm VERY happy you posted your experience here. You documented convincing direct evidence that the Chrysler test does have at least some false negatives, meaning that in the setting of clear signs one shouldn't be dissuaded from moving forward. In my case I'm not losing oil, yet, so I've held off for now. But I don't think I would hesitate if I were having more definitive symptoms.
yes, I'm hoping I don't have to do this job for my truck but it would always be good to have a good video on it, my 2000 dodge ram has 139,000 miles on it, its got the 5.9L
I was looking forward to it, Alex. I even have the Hughes kit, and I'm not returning it since it may be in the works one day. If I have to remove the plenum for another reason it will certainly be done. But at this point I'm not going there.
Thank you for watching.
Thanks Dave for the input and let us know how it goes. I know you'll get it figured out.
Great point, your experience really improves and balances the discussion here. Nice to meet you!
Thank you very much for this excellent video. It was very helpful! I was about to tear into the intake but now I am at the conclusion.
mine had failed, 98 ram 5.2 318 laramie ext cab, the model with no back suicide doors. i did a rebuild due to what i thought was a blown head gasket, i had water coming from exhaust..truck idled perfect, it ran perfect no misfires that u could see by running it or idling, had power i could burn the tires and never stall, well headgasket was warped just enough to allow leak, i had the number 8 misfire weve all been warned about.. but my plenum gasket was damn near completely gone. i didnt expect it and was luckily planning on changing it and already got it lol. it was so thin and wore away. id say 30% of gasket material was left..40% at best and thats pushing it..i have some dragster buddies who love buying old cars rebuilding them they race them till there sick of them then do it all over again, they helped me and they couldnt believe how good my truck ran at the time 250k miles, bad head gasket, it took 10-15m to overheat, almost no plenum gasket, oil pan gasket and valve cover gaskets, throttle body gasket gone, i had oil on the plugs, water pump had sheared some propeller fins off too you couldnt tell till disassembled. and untold ammounts of sludge builtup, mustve used 30 cans of carb cleaner..if it hadnt been over heating u wouldve said the truck ran perfect lol it was incredible.. i love the truck i still have it after 10 yrs ive had many vehicles come and go but not it..its my toy, my best friend, my one true love lol and it earned that, it wasnt an immediate thing
Great story, thanks for taking the time to leave it here.
mine had failed, 98 ram 5.2 318 laramie ext cab, the model with no back suicide doors. i did a rebuild due to what i thought was a blown head gasket, i had water coming from exhaust..truck idled perfect, it ran perfect no misfires that u could see by running it or idling, had power i could burn the tires and never stall, well headgasket was warped just enough to allow leak, i had the number 8 misfire weve all been warned about.. but my plenum gasket was damn near completely gone. i didnt expect it and was luckily planning on changing it and already got it lol. it was so thin and wore away. id say 30% of gasket material was left..40% at best and thats pushing it..i have some dragster buddies who love buying old cars rebuilding them they race them till there sick of them then do it all over again, they helped me and they couldnt believe how good my truck ran at the time 250k miles, bad head gasket, it took 10-15m to overheat, almost no plenum gasket, oil pan gasket and valve cover gaskets, throttle body gasket gone, i had oil on the plugs, water pump had sheared some propeller fins off too you couldnt tell till disassembled. and untold ammounts of sludge builtup, mustve used 30 cans of carb cleaner..if it hadnt been over heating u wouldve said the truck ran perfect lol it was incredible.. i love the truck i still have it after 10 yrs ive had many vehicles come and go but not it..its my toy, my best friend, my one true love lol and it earned that, it wasnt an immediate thing
Good test :-), even a non mechanic like myself can understand it :-)
So some other part of the engine is blowing raspburys at you lol :-)
I have a 2000 Dodge Ram 1500 with a 360. It only has 125,000 miles on it. Just recently started running rough as it comes up to normal operating temperature. It runs fine when I first start the engine. After a bout 2 or 3 minutes it starts to run rough. After it comes up to normal operating temperature, in runs and idles fine. Cold engine=runs well and warm engine=runs well. In between, just for a minute or 2, not so good. Plenum?
Hard to say. I suppose a pan gasket could do that although it wouldn't be typical. As a first effort I would put the engine onto a scanner with real time data, looking at oxygen sensor values, fuel trim, IAC position valves, etc. Before going too far down the diagnostic pathway it would be wise to catch up on any overdue maintenance items such as air filter, plugs, distributor cap, etc as outlined in the owners manual. I wouldn't replace any other parts unless justified on the basis of diagnostic tests.
@@spelunkerd Plugs, wires, distributor cap, and air filter all replaced last year. I have two code readers but I don't think either one has real time data. No codes or engine light. I guess I will have a mechanic put it on a scanner. I am the kind of guy that isn't afraid to turn bolts and replace parts but my diagnostic abilities on automobiles is limited to what I can find on RUclips or forums. :)
@@4150CHF Those are wise words. Even if you do the work yourself, an hour on a diagnostic scanner with an experienced tech will take you much farther.
@@4150CHF One other thing that I often forget when dealing with variable rough idle is the EGR valve. If your EGR is sticking open, or perhaps has cracked tubing, you could get a variable rough idle that might seem to improve as the vehicle warms up.
@@spelunkerd It doesn't "seem" to improve. It is very obvious that the idle is normal at initial start-up and then becomes rough after a two or three minutes and then becomes normal again after another minute or two. This is without exception. It happens every time, like clockwork.
Thanks for the info, mine seems fine
I noticed at idle that the vacuum gauge had a very slow drift and then the needle would smooth out when you increased the rpm, which to me would indicate possibly a small vacuum leak on the manifold side. From your test of the plenum pan, it looks okay to me. Did you take a look at your IAC count value to see where it's at. If you did have a vacuum leak, the pintle on the stepper would shut off the passageway because of increased air. If you see a very low value or 0 then you have a leak. cont)
If I remember, your LTFT's and STFT's are about -1.5% and then normalizes after it warms up and I assume that this is for both banks. From those values, there really isn't anything showing out of the ordinary. In any event, take a look at the IAC count and see what you have. If there is a leak, it would show up here.
There is normally some oil there from the PCV so that's not a very reliable test. A compression tester is pretty cheap, but in your case it might be better to take it to a pro so that you can be more confident in the answer. A quick professional opinion might save you some dough in the long run and give direction (replace engine or cut your losses before spending more). Even if the pan is leaking, if no compression the problem is bigger....
Gee, any codes? The list of problems you describe are characteristic of a plenum leak, the lack of confirmation notwithstanding. Is yours a gen2 Dodge Ram? If it is, I think I would be inclined to go after that pan gasket anyway. Have you done a compression test to look for more serious problems? A bad cat should be an easy diagnosis.
One option would be to take it to a pro for an opinion. You could still do the pan gasket yourself, but what you are asking is for a professional diagnosis....
You might want to check the wire routing - Chrysler put a lot of emphasis on correct routing in their dealers manual. I would do a compression test on that cylinder, and maybe a leakdown test. Is the injector there working properly? You might find more helpful advice on one of the forums -- I spend some time on the free forum at ericthecarguydotcom
I haven't returned the Hughes kit, thinking that at some point I'll have to do it. But for now that plan is on hold. I'm actually a little disappointed since I was hoping for a definitive fix and I was looking forward to trying to improve on what is out there as far as videos go.
Embossed on the intake manifold should be the firing order...1-8-4-3-6-5-7-2 as well as 12ft pounds of maximum torque. After doing close to 15 of these plenum pan gaskets, they generally leak closest to the bulkhead/firewall. Cylinders 8 or 7 which of course oil fouls the spark plugs compromising the secondary ignition system thus resulting in misfires, especially at idle. One thing to keep an eye on is once the engine is up to operating temperature, if higher than normal tach is present(rule out dirty throttle body, etc) chances are the engine is consuming oil. I take pressure readings(pressure being what you want to see indicated on a gauge) directly at the dipstick tube. Any large measureable amount of vacuum there is a red flag. On another note, I have re-used the manifold bolts(I do this for a living and know what I can and can't get away with) If I recall correctly, the pan bolts are 11mm and should be torqued to 7ft pounds or 84in pounds. After removing the intake manifold assembly, plug the intake runner ports and pour some water in the assembly. If you see water leaking out of the pan, well, you know what to do. This is similar to checking valve seats and stem seals(cylinder off obviously) Being a Dodge product, do not be surprised if an idle relearn has to be done after re-assembly is complete. Now is a good time to change the valve cover gaskets as well and make darn sure the PCV is not plugged up. During the removal process, don't even worry about the fuel rail, leave it alone(unless you want to replace injector O-rings) If I can think of anything else, I will post it later.
It's great to have a pro stop by, thanks for your insightful comments.
I have a 99 Dodge Ram 1500 every time I start my truck sounds like it’s sucking air in my carburador and if I keep my truck running it goes away but when I drive it up the hill it loses speed and I push gas and it goes slower that means my plenum gasket it’s bad
I did a video of cleaning the throttle body that might help. The other resource if you haven't already found it, is dodgeforumdotcom. Lots of traffic and some people with experience there. I would do a compression test on your engine first. With an engine that is almost 20 years old, worn rings causing oil loss and bad compression could explain everything.
Thank you. What I don't know is the sensitivity of this test, ie can I exclude gasket failure if the test result is normal? Chrysler say yes, but I'm not so sure. It sounds to me like most people don't bother to do the test, instead replacing the gasket and plenum when suspicious problems arise.
I'm burning out cats, taken it in twice and one guy says plenum gasket other guy says injectors. I'll try this test. Thanks. B3500 Van. First time I did the oem cat, second time was amazon, both burned out and my exhaust is super rich smelling, get 9-10 mpg.
Those are good thoughts. You might consider doing a compression test to be as sure as you can that more investment will be worthwhile. Pan gasket problems were unique to this generation of dodge ram.
If your magnum engine uses more than normal amount of oil per 500-1000 miles its the plenum gasket . It's that easy , this is nice , but over the top .
That's a good point, but I'm not sure I would be so confident, especially in old engines with suspected ring wear. Before committing to major engine work I would want to have all the objective information, perhaps even a compression test.
spelunkerd , I hear you , I like your video and how analytical you are . Quick way to tell , really easy is to take the air cleaner housing off , open the butterflies and look down with a flashlight and if there's oil its the plenum gasket . That's how I checked mine and it turned out to be the case . Really Good videos though !
I'll try this test tomorrow. Thanks
I have a 99 dodge ram 5.2 v8 I'm TRYING TO SEAL ALL LOOSE ENDS IF I CAN GET ADVICE WHERE TO FIND LAYOUT/DIAGRAM LET ME KNOW SO I KNOW WHAT ALL PARTS ARE AND WHERE THEY GO/FUNCTION. I'd LIKE TO BE ABLE TO TAKE ENTIRE ENGINE APART AND KNOW WHAT EVERYTHING DOES ETC. gOD BLESS. p>S. GET SUM SWAG
+Jason Edward The most economical and accurate option is on online dealers repair manual, either alldatadiy or Mitchell. For a 5 year subscription (about $35) you get updated TSB's and the full dealer repair manual, with lots of additional detail. I wouldn't work on a car without it.
Thank you very much. Your video was simply and clearly explained and quite helpful. My '99 Ram 5.9 2500 manual trans, just out of nowhere, decided to fall flat upon even very light acceleration. I pulled a code P171B ('Left Bank Lean'). My test results were as exact as yours so at least now I know it 'shouldn't' be the plenum. No idle problem, pinging, backfire, detonation, etc. Just goes 'Bleeaahh' and dies flat out of breath. Always starts right back up and idles all day but same thing when you accelerate again. Also, 99's (at least this one) do not have a MAF sensor.
Much appreciated.
Interesting. I'd be going for fuel delivery (fuel pump or fuel pressure regulator, etc), or maybe a clogged cat. I don't know if the '99 has a MAF sensor, but if it does then a dirty MAF can do the same thing (the '98 has only a MAP). I would take the air filter off and have a look there to make sure no rodents have made a nest that obstructs flow in the air intake somewhere. First thing I would do is measure fuel pressure from the Schraeder valve with acceleration and if that is OK then measure exhaust back pressure upstream of both cats. If you have a MAP like the '98, check that the little vacuum hose that comes off the MAP is connected correctly with no leak or crack in the tubing. Lack of difficulty at idle goes against a typical vacuum leak. Good luck. One word of caution, I would not start replacing parts before diagnosis. Getting a diagnosis from a pro often doesn't cost too much, and may be much less expensive than blindly replacing parts without proving they are bad first. So if I didn't have the tools necessary to make the diagnosis I wouldn't hesitate to get advice from a pro.
+Charles Rendine Ha ha! This morning I turned on the computer and found a video that describes a similar situation in a similar vehicle. Go to SouthMainAutoRepair here on RUclips, and find the recent video published today "Dodge Ram 5.9 gas, no power..." That one was running rich, clearly a clogged cat, he shows how to make the diagnosis. Let's hope yours is not that, a new cat is expensive. Yours is running lean, it could still be a fuel issue, so don't assume yours is the same. I hate to see old trucks like this hit the junk yard, if it were mine I would do it myself and try to keep it on the road. Good luck, please stop by and let us know how it turned out.
Is there any way I can bypass oil going through the plenum gasket leak, like a oil catch can, or do I just need to replace the gasket period?
When the pan gasket leaks, it is over a long RTV line so something like a catch can doesn't work. Even so, the replacement is simple enough and very effective for these old trucks that have the defect. Many of these old trucks are already in the crusher, never experienced a leak, or have already been fixed. The standard replacement, a Hughes plate, is aluminum. So, if you place a magnet on your plenum plate you can quickly tell if it's been replaced with a Hughes kit. The tricky issue is regarding how much oil is too much, and whether there is even a leak! The dealer information says that if you don't have vacuum in the crankcase, the repair is not needed.
You’re awesome!
Thanks for the advice!
I didn't need a gauge. I took the oil filler cap off and right away there was a vacuum I could feel by placing my hand over the oil filler cap hole. I bought the Hughes kit and when I removed the intake the gasket was totally failed and blown out. My truck was pulling air from the crank case. Since the Hughes kits was installed I have more horse power and no more pinging climbing a hill.
Excellent point, that's a shortcut that experienced techs go to first, I forgot to mention it. Of course that shortcut is not as sensitive as doing the test as I did here. On internet forums, some people claim that this gasket fails so often in the gen II vehicles, it's not worth testing, just fix every one. I don't agree with that remark, but it does raise the interesting issue of false negatives. The official Chrysler line is not to fix it unless this test is positive, and if the leak is so small you can't detect crankcase vacuum, I would wonder whether fixing a tiny leak would make any difference. It certainly wouldn't help the dominant issue with these trucks, gas mileage.
You wouldn't happen to know to get something of better quality like the Hughes kit but for a V6, would you?
Hey so my dodge can hold the oil cap with thw suction that it has is that bad?
I have a question regarding your 98' ram. The fog lights. I'm going to put fog lights in it. Reuters. Wires to fuse box and install the lights. Can you tell me how the switch works for a 98 for fog lights. Or I'll have to get a new switch
Mine doesn't have fog lamps but I scrolled through the dealer service manual for you on alldatadiy and I found some details about the fog lamp circuit and switch. When installed in some versions of the Ram, the fog lamp switch is on the right side of the dashboard bezel, and they show how to replace the OEM switch. There is a fog lamp switch relay in the main fuse box. I suspect the wiring is probably already intact and you just need to install the switch and lights. However if you're installing LED lamps then there is more to it.
@@spelunkerd ohh... ok. So, their's whole nother switch. Crazy... no existing wires. Running all wires or yank it from a parts yard. I mean... not that hard to wire a relay. But I'm going to wire it through the fuse box.
Spelunkerd
I bought a new injector but when I got home I decided to switch cyl5 with cyl1 hoping the misfire would follow the injector, but to no avail
P0305
oh yeah on a cold start Truck has rough idle then after a few seconds it goes away.
I feel like that guy in the Comercial where his car is a big baby!
This sure beats peeking through the throttle bores looking for oil..
Yeah, there's normally a little oil that comes in through a normal PCV valve, so it can be hard to make conclusions about that.
Did you ever end up finding the problem or replacing the pan?
Good question. This truck has had a subtle misfire for years, on and off. At times it improved with fuel injector cleaning, and at one point it improved for a while when I changed plugs and wires (video done). I never did replace the plenum pan, and although I actually got the Hughes kit, it is still sitting in the garage, waiting for the day I have the intake off. More recently about 4 years ago I did a series on the Picoscope laptop oscilloscope, and to my surprise I found an abnormality on cylinder 4 that I traced back to a defective, fairly new plug! It made for an interesting video, the first on the Picoscope playlist on my channel. If you look closely at the plug you'll see there is a defect in one of the electrodes, it almost touches the other side. Changing the plug solved that problem. Early this year I noticed the abrupt onset of a dead miss, and I went straight to the labscope to nail it down as an open plug wire contact where the wire was attached to metal prongs of the plug terminal. The voltage on that wire was through the roof compared to all the other wires, and at the defect there was black powder from the contents of the wire. I was too busy to video that one but it was another easy diagnosis with the right tool. The truck is still used almost every day to haul brush, dirt, and garden debris. Working great!
spelunkerd, how's it going, so I've got a 1999 dodge ram 5.9 v8 4x4, when I check the oil with a cold engine it says zero, when I check it with the engine warmed up it says over the max amount.the oil pressure is at 40, I use mobel 1 10w30. it has been recently idling funny when in park it wants to shut off and has a small ping. I put seafoam into the gas and and the engine about 2 weeks ago could the seafoam have caused a problem? or what could the problem be?
I noticed when I openned the throttle body on my 5.s Magnum there is considerable oil on the Plenum pan, I had to replace both the Breather element and PCV valves recently. The oil does n't contain a sweet smell cold or hot and the engine stalls at about 130 when not level. any thought?
That's will make the idle pump up and down a little ?
Yes, a vacuum leak typically has a dramatic effect on idle speed, usually increased in a bumpy kind of way. When the throttle butterfly opens, there isn't much vacuum to draw unmetered crankcase air into the intake, so on live data you usually see lean conditions improve at wide open throttle. That's the classic way to spot any vacuum leak, it differentiates it from other diagnoses such as fuel delivery problems (MAF in some vehicles) etc. That said, with a big plenum leak you get more oil drawn into the intake so it may be more complicated (oil consumption, black exhaust, sometimes poor acceleration). Since that oil can sit inside the intake, the association with throttle position is not so clear. In old vehicles the challenge is to differentiate that from more serious problems like leaking rings, poor compression, valve issues, leaking PCV valve, etc.
Well, on this engine, a misfire, pinging under load, and oil usage almost always lead you to a blown plenum gasket. I have recently found, from experience, that if allowed to go too long, the blown plenum gasket could be possible cause of head gasket failure. If this is true, is it possible this is because the oil enters the combustion chamber as a liquid, causing excess pressures inside?
I don't have detectable vacuume in th crank case but lookin down through th throttle body you can see a lotta oil on th bottom of th intake an thier oil residue on th bottom side of th throttle plates. Engine smokes pretty bad when it's been sittin a while it don't immediately go away but it does after you drive it a while
Have a look at the PCV valve to be sure it is not stuck open, these should rattle when you shake them. Overfilling with oil could be a factor, many of these have oil in the plenum normally, so it's a tricky question if vacuum is normal. Typically a leaking plenum gives other problems, and many of this generation are already fixed at some point. Replacement plenum pans are nonmagnetic, and the OEM pan is steel, so you can tell easily with a magnet.
@@spelunkerd yea it's got 173000 miles on it and I believe it had the original PCV valve on or it had been on it for years and it was stuck. Hose from it over to th manifold had a lotta oil in it and a lotta oil in th manifold. I changed th PCV valve and hose and with it runnin at a high idle sprayed a lotta air intake cleaner down th throttle body and took it out on th interstate and ran it about 60 mph for about 10 miles. It's quit smokein but when you look down through th throttle body you can still see a little bit of oil but not like it was. I guess il run it for a while and see how much it's usein. This is th 2nd 01 dodge iv owned and this is th first iv heard of em doin that. I just wonder how many people have put engines in them trucks couse they didn't know about that thing. All an all tho that 2nd Gen dodge is rugged dam truck
Do u know or have info of dakotas and this problem
The Gen 2 Dodge Ram had this problem, these vehicles are almost 20 years old now. Mine was a '98, and most were within a few years of that date. When it was discovered, Dodge modified their procedures to correct the defect, which came from differential expansion of aluminum compared to steel as the engine heated up.
hi, i have a 1994 318 magnum on a jeep. i did your test, got no vacuum, but only got about 0.5 psi positive prssure. looking inside the the plenum i see usual oil spatter but no pools. oil loss is half qt per 5000mi, have no blue smoke, typically bad 318 mileage 12-18 mpg lol. a little pinging climbing 7 % grade but goes away with the OD turned off. the slight oil loss seems from leaky valve cover gaskets. i wonder if thats why i cant get the positive crankcase pressures you get? ps thanks for the video.
There are lots of variables as far as crankcase pressure, air can also escape through the dipstick, too. I would dismiss the minor variance between mine and yours. This plenum pan gasket problem was an issue with my specific vintage of truck, but I don't believe the older trucks like the '94 were especially prone to it. The main problem was the way some parts were aluminum, some steel, and with the difference in thermal expansion coefficient, they saw problems that were only rarely seen in older all-steel trucks. There were major design changes in about 1997-8. I'd have a look at your PCV valve, make sure it rattles when you shake it. I wish my mileage was as good as yours, ha ha!
@@spelunkerd hi, replaced the pcv and the rubber grommet last summer. but just discovered my latest vacuum leak; its a faulty EGR solenoid leaking and also the egr valve never opens. they last maybe 2-3 years from my experience. so now my gas mileage may go up from 12 to 12.5 haha. thanks for your feedback, keep up the good work
@@FrenchmansFlats51 Ha ha, I always forget to think about the EGR, it's a sleeper diagnosis. Thanks for the followup!
oh man If you do a full plenum repair that would so so helpful for people, because there isn't really a great video ive found on it.
I wish I knew about this long time ago I'm starting to think Dodge only makes lemons
Good stuff.
I did a similar test, but with just holding my finger over the pcv vlave, and otehr end blocked too, like you I could not detect vacuum but pressure. So I'm looking elsewhere on where 3 quarts of oil went on the last tank of fuel, no smoke I can see.
Its keeps blowing O2 sensors tooo, getting tired of it.
Thanks for the video.
You might start with a compression test. I wouldn't discount the idea it's the intake gasket, and if other things fit and if the engine seems good you might go ahead anyway. Any test will have false negatives.... If it does turn out to be the plenum pan gasket, please stop by so others will hear your full story.
2002 ram 1500 5.9 error code po 300,303,305 off and on with rough idle? Changed wires,plugs, cap.rotor, All had to be done anyway.Ran a bit better but rough idle and misfire seem to be an issue.
Lots of things can do that, and investigation of some may require more specialized equipment than you have access to. I'd probably start with a compression test, and if that's good I'd check the battery and look for a vacuum leak. I'd also double check your wire routing and contacts, since it would be very easy to mess that up on this engine. Yeah, the look at crankcase pressure might show something with this particular engine. If all that's OK I'd check fuel pressure and maybe consider putting a labscope on, to search for more clues. I would avoid replacing any more parts until you have definite evidence of what is wrong. All told, unless you feel comfortable doing all that it would be wise to ask a pro to help you out. Diagnostics is an underpaid service and it may help you to avoid very expensive mistakes.
I have a 1996 Dakota sport 5.2 4x4 5spd short bed. I bought 7 months ago, on trip home I averaged 17.3 mpg. I added shorty headers and flow master 40 muffler and I averaged 19.73 mpg. I bought the Hughes airgap manifold since everyone was Gaga about it. My mileage now is barely 14 driving gramma speed. What gives? With stock manifold I could drive it hard..80mph consistently and get hair shy of 20. Now I can't get over 14. It revs quick and easy but figure my vacuum leak is better. I'm gonna yank off and throw the $600 manifold in trash and go back to stock.
The Hughes plenum repair fixed a vacuum leak, which is mostly a problem
at idle when the engine is not driving the vehicle forward. By
definition, any fuel consumed at idle is therefore wasted energy, so the
engineers designed the engine to run at an idle rpm as low as possible.
After the repair, vacuum at idle typically increases. Increased vacuum
at idle draws in more air, which will be detected by the upstream oxygen
sensor, in turn sending a transient lean signal to the PCM. When it
detects a lean signal from the oxygen sensor, the PCM is programmed to
react and deliver more fuel from the fuel injectors to regain balance of
the combustion products. So, I would expect more fuel consumption after
a Hughes repair when the car is not moving. Indeed, many people who
have done the repair complain that fuel mileage is not improved. Of
course the story is a little more complex since the faster idle rate
would trigger the iac valve to close down and then slow idle rpm to spec
values. Also the PCV valve delivery volume fluctuates depending on how
much vacuum is present. With all that complexity, the practical
observation about fuel consumption has to go back to what people see.
Almost nobody says fuel mileage is improved after the plenum pan repair.
If you go back to a stock intake, I wouldn't be surprised if your fuel
consumption does not improve, since you probably had a manifold leak
before the new intake was put on. Good luck!
I had a 97 Dodge Ram 1500, 5.9. 215xxx. I've noticed a ticking noise when I accelerate. I'm thinking it's a manifold leak. So I'm asking is a failed platinum gasket could cause that has well? I believe another way to tell if it's blown to take the air filter off and see if there's oil sitting down there.
+Willie Gusa There is normally a small amount of oil at the base of the intake manifold, coming from aerosol oil that makes it's way through the PCV valve. You should have a demonstrable vac leak and measurable oil consumption before considering a manifold gasket leak. Ticking has not been a big feature, and in fact the throttle butterfly is wide open during acceleration so vacuum leak issues like the plenum pan gasket failure are generally reduced with increasing throttle.
I have a 99 Ram 5.2L with a popping coming from the throttlebody while under load -i.e. pulling a hill in OD or under heavy acceleration. My fuel economy is around 12 so I believe it could do better. I have replaced the upstream O2 and downstream O2 sensors. The truck has around 180K. What could I check to further diagnose this issue?
A bad pan gasket could certainly cause what you describe. Are you using any oil? I would look for evidence of pan gasket failure first, unless the repair has already been done. If you are not sure, a magnet on a stick into the intake plenum may help. A lot of guys get 12 mpg with this generation of engines, especially if there are big tires or a lifted body.
Looks like I'm about to do this test. My truck is at 138k miles now. Symptoms/other details:
I burn 2-3 quarts every 5-6k miles.
Occasionally I get an intake backfire when snapping to WOT.
Idling is ever so slightly rough.
I do occasionally get pinging at cruising and WOT.
Spark plugs look decent, and it never blows any oil smoke out the exhaust.
Dry compression is 150-155psi in all cylinders, which is decent.
Gas mileage is 12mpg city and 18mpg highway, this is on a 2WD 5.9L.
Yeah, I'd do that.
Hello Spelunkerd,
Same as other intros.....I have a 99 SLT Laramie 5.9 with a boatload of miles on her! I have changed, replaced, and added numerous mods to the truck throughout the years. If i can't fix it, I send it a local shop. Now the question I have for you is: My truck runs great, idles fine, and has no issues other than this one I cannot figure out........it chugs hard between 40 -45 mph. It accelerates fine up to that speed and rides well after going beyond 45, just an added not. I have a new tranny, new exhaust system, use 10-40 Mobil 1 Syn, and tons of other stuff. I need your input as to what you may think the issue is. An idea is more than enough. I was thinking a new distributor cap, coil, wires, and plugs should do, but I'm asking you before I do something that I don't need to do. Thanks for your advice.
+wannabeangler Sounds like a transmission shift timing issue. Perhaps RPM's are too low at that speed to get much torque from your engine. You get better fuel consumption at low RPM, but less torque for sudden acceleration. I don't know if that can be reprogrammed but there is an overdrive switch on the end of the shift lever which can be pressed to change the shift pattern. Of course you can shift manually, too, though that can be annoying. With such an isolated issue at certain rpm, I doubt general efforts would have much effect.
I have an 04 ram 1500 3.7 and it's burning oil. No smoke out of the tail pipe but I can smell it when I'm standing in front of the engine. It's not burning at an alarming rate but I do have to add oil in between oil changes. Also, there seems to be moisture getting in there because when I pulled off the cap, there was some milky beige foam on it. It runs fine, doesn't smoke or make strange noises. Any idea?
Could be a head gasket or bad rings, maybe a coolant lead somewhere. I'd start with a compression test, look for codes, check for exhaust byproducts in the coolant system. Milky oil is usually an ominous sign, although once before I found it with a simple coolant leak and secondary overheating. A much more common cause is a bad head gasket.
Excellent video, thanks! I looked in my 5.2 Durango intake. Is this Hughes plate cast aluminum? What about the stock sheetmetal it's steel? The one in mine looked pebbely like cast aluminum, possibly mine has been done already....
I know its late, but stick a magnet down the throttle and see if it sticks. If it does, its a stock plate, which may have had the gasket repaired at the stealership but blew again, thats what they do. If it doesnt stick, then it has an aftermarket aluminum plate in it. Hughes wont look pebbly, it will look machined.
Spelunkerd, as a novice, I hope this isn't a silly comment, but your pressure test was performed with the hoses closed off with tape, providing a known consistent environment. Is it possible that the idle problems you experience once the original equipment is back in place points to a failure of the PCV valve or other connected original equipment hoses/devices?
+Scott Jenkins That's a good point. When I looked at the PCV valve it was working fine, with a nice rattle and normal flow on simple bench testing. Even then I replaced the PCV simply because it was 14 years old, and I thought about making another video. Never got done, ha ha. Thanks for watching!
Working with my mechanic: my dodge, 4x4, 230K miles, acts like it is missing when starting off from stop or idle then goes away after 25+ mph, although had a few backfires running downtime highway 60 -70 mph. Scanner shows P0300, wa first suspecting O2 sensors in breather or at catalytic conv. But Mechanic is suspecting leak around intake gasket as spraying combustable fluid along gasket in back causes engine to try and die. He has replaced plenum gaskets before, especially Fords, stuff getting cheaper all the time. His guess is to replace gasket and hope plastic plenum still fits tight, if not go back do plenum as well. Maybe both at same time. Between makers, all a little different design. Anyone thoughts????
What year? If you spray water on an intake leak the RPM will fall, if you spray combustible fluid right on the air leak it will rise (opposite to what you describe above, did you get it backwards?). Even by itself that is a very powerful finding, so if it was definite as I describe above then the diagnosis seems pretty clear. I agree, the symptoms and a decreased RPM with water are suggestive of a vacuum leak, and more evidence to support that would include positive fuel trim on live data that normalizes when RPM increases. If the findings were not clearly convincing I would verify them on a scan tool, in part because other things (like a stuck open EGR valve, etc) can present in the same way. Vacuum leaks tend to settle at faster RPM because the manifold vacuum is lower so the leak will improve. The test I did above was for a specific plenum pan leak where air is getting in from the crankcase, not from the topside of the engine. A plenum pan leak by itself will show no change when spraying water or accelerant, since it is completely isolated from air above. That said, if your Dodge is of the vintage prone to pan leaks, and you have to go in anyway, it makes sense to replace the pan at the same time. In that MKII model I would use the Hughes kit, it's not that expensive and it's got a good track record for the plenum pan leak in my generation of vehicle. However if your intake is plastic then your truck is newer than this one, in which case it is likely not so prone to pan leaks into the crankcase. Plastic intakes are very prone to leaking over the years, and the story sounds typical. Good luck!
mine had failed, 98 ram 5.2 318 laramie ext cab, the model with no back suicide doors. i did a rebuild due to what i thought was a blown head gasket, i had water coming from exhaust..truck idled perfect, it ran perfect no misfires that u could see by running it or idling, had power i could burn the tires and never stall, well headgasket was warped just enough to allow leak, i had the number 8 misfire weve all been warned about.. but my plenum gasket was damn near completely gone. i didnt expect it and was luckily planning on changing it and already got it lol. it was so thin and wore away. id say 30% of gasket material was left..40% at best and thats pushing it..i have some dragster buddies who love buying old cars rebuilding them they race them till there sick of them then do it all over again, they helped me and they couldnt believe how good my truck ran at the time 250k miles, bad head gasket, it took 10-15m to overheat, almost no plenum gasket, oil pan gasket and valve cover gaskets, throttle body gasket gone, i had oil on the plugs, water pump had sheared some propeller fins off too you couldnt tell till disassembled. and untold ammounts of sludge builtup, mustve used 30 cans of carb cleaner..if it hadnt been over heating u wouldve said the truck ran perfect lol it was incredible.. i love the truck i still have it after 10 yrs ive had many vehicles come and go but not it..its my toy, my best friend, my one true love lol and it earned that, it wasnt an immediate thing
im getting the number 8 misfire it doesn't do it all the time but when it does truck almost dies at idle rough as hell then it throws the code and if i turn it off and on again runs fine sometimes for days sometimes for a Minuit what causes the number 8 misfire
GREAT VIDEO, IFOUND VACCUM IN MY CRANKCASE AND ORDERED A HUGHS PLENUM REPAIR KIT. BOUGHT A VACCUM AND PRESSURE GUAGE FROM HARBOUR FREIGHT FOR 15..DOLLARS TO TEST PLENUM
Hey, thanks for the feedback! Although I can understand false negatives with this test, I think a false positive like this would be VERY unlikely. Please let us know how it worked out.
I have a 96 ram 1500 5.9L (gas) 150,000 miles and sometimes it has lack of power and second was a 50 mm holy throttle body stock cause my truck had one when i got it
And i only get 10mpg
I have a 2001 Ram 1500 Quad cab 4x4 w/ the 5.2. I have done the test about 3 times, I think. And every time i have done it, i get no indication of vacuum where it shouldnt be, ie, it "passes". I too wonder if i am getting a false negative. It has +260k miles on rhe clock, it seems to idle fine to me, just an occasional flutter that I expect older vehicles to have, I hear a hiss, like a vacuum or intake leak that i cant seem to pinpoint, oil use seems high to me even for a high milage vehicle, gas milage sux even for a Dodge halfton, and it pings under load. I am stumped as the symptoms point to the plenum gasket but the test says look elsewhere.
If you hear clear hissing, the story is pretty typical of a vacuum leak, somewhere. A smoke test of the intake would quickly diagnose a vacuum leak, and if you get smoke coming out the oil fill port or dipstick tube, the leak would be internal through the plenum pan. I suppose you could do that with a cigar if you don't have access to a smoke machine. Remove the air filter housing, and clamp the PCV hose, put a plastic bag held tight by an elastic band over the throttle body intake, blow smoke into a vacuum hose and watch to see where the smoke appears. You may find one you can rent. There are many videos showing how to make a smoke machine, and Ebay has one for sale that is said to work fine (search Stinger smoke machine on Ebay, I have no personal experience with that one). Another option would be to ask a pro to verify the diagnosis, I don't think it would cost more than an hour of shop time to get a diagnosis, which you could then fix yourself. They would be able to use a pro level scanner which might help to verify a vacuum leak by looking at fuel trim patterns. Interestingly, poor fuel mileage is not typical of Dodge plenum pan leaks, so don't expect fuel economy to improve. It's bad in all of these trucks, we learn to live with it. The last time I had a fishbite miss at idle, it was a bad plug, which I found when doing secondary ignition analysis with a labscope. One common area for a vacuum leak in the Ram is the MAP sensor vacuum tube that is concealed under the MAP sensor. Don't forget to look for misplaced vacuum hoses, it would be a goofy thing to forget. The other area air can make noise is where the air filter housing rests on the throttle body, it sometimes can go on cockeyed and give a leak there. However since that is outside the throttle butterfly you don't get vacuum leak fuel trims, it just makes noise. With high oil consumption another option would be to do a compression test in an effort to decide whether more aggressive procedures are worth while. If compression is poor, you may save money by doing that kind of testing up front.
I tested my vacuum just basic test no blocking off anything but its about 10- 21 then warmed up drops to about 8 to 10. how weird is that? whats your thought s on it?
At idle, 8-10 is too low -- time to look for a vac leak. If the rest of the test passes, I would consider a smoke test if you can't find an obvious leak. With warming, the leak is evidently larger, wherever it might be. The stock plenum pan is made of different material than the block, with a big part of the pan defect being differential expansion under heat. But that could happen in other areas, too.
^^This guy knows his mechanics...^^
He's pretty good!
Im thinking intake. But I need to smoke test
update> i was wrong about the vacuum. im pulling 15 to 17 inches of vacuum once warmed up. its steady but moves back and fourth. I"m thinking either throttle body gasket and/or intake. what do you think?
how to fix smoking problem
Would bad plenum cause smoke bellows on cold start acceleration?
Not usually, I'd be thinking valve stem seals or maybe bad rings.
spelunkerd ok interesting, did dry wet compression test and about 100/110 across all 8 . I can see oil on plenum 2000 5.9 225k miles
Should’ve listened to you 3 hours later no plenum Failure. Pulled for nothing .
Hello. 06 Commander 5.7l with coolant leaking into #4 cylinder. Both spark plug electrodes in #4 were detached from plug and throwing an 0304 code. Replaced both plugs and now that I have spark in that cylinder im getting white smoke from tailpipe. Crankcase oil is clean. Do you think plenum is bad? Or maybe plenum gaskets? Engine cranks normally with no symptoms of hydrolock in a cylinder.Thanks
Head gasket leak, a bad plenum pan gasket by itself won't do it. You could check for exhaust gas inside the cooling system, but the story sounds convincing even without that. Good luck!
@@spelunkerd Thanks for weighing in. Had a 3.8 GM engine that had identical issue. Coolant passage in plastic plenum was breached. It was a bad design. Had all the symptoms of a bad head gasket but was the plenum. Thanks
I've got positive pressure as you did but do see some oil in the intake through the throttle body and get a ton of blue smoke under load and after revved
Before going too far I'd do a compression test to look for bad rings as a cause. If you've got a bad cylinder there is not a lot of reason to go further. If compression is consistently good in all cylinders, I suppose it could be a plenum pan issue, though it is a little unusual not to see vacuum in the crankcase if it is leaking so bad as to cause blue smoke. Make sure the PCV valve is working, that would be a goofy cause if overfilled with oil. The other thing that can cause blue smoke is leaking tappet seals, though that problem is almost always at startup only.
Dave, I just thought of something else that might be beneficial to you if you decide to pursue doing a plenum pan repair. Once the intake manifold assembly is reinstalled, go ahead and reattach all of the cooling system components(miles well change the thermostat(180F or 195F) while you're there, also the bypass hose. Fill the cooling system with enough ethylene glycol coolant so that you can do a pressure check of the system with a pressure tester. I would do this before reinstallation of the accessory drive bracket, alternator, ac compressor, etc. I would rather know if there is a leak now, than have to tear it all apart again. The factory cylinder heads are known to crack, especially close to where the intake manifold meets the head. Being preventative never hurt anyone. Your name is Dave right? HaHa
That's a good thought. I've seen guys do that, usually when they replace a head gasket and find no abnormality of the old gasket. Then they start to sweat over whether the block or head might have a hairline crack. Lately my truck has been running great, so the plenum pan is going to wait....
Yeah, it's Dave, ha ha.
Hello spelunkerd, I have a 99 5.2. don't much lately but it just started smoking blue at startup and then turns white, Allot of smoke. I know its not the Trans fluid, Pressure builds fast in the cooling system. The change of color confuses me a bit. Have not tested compression yet. Never had any issue with the truck always ran great. Let me know what you think .Thank You.
+Golfingferdie That sounds like coolant is making it's way into a combustion chamber. The commonest place for such a leak to occur is at the head gasket, and such a leak is usually two-way, with combustion gasses also making their way back into the cooling system. Such gasses are most easily detected with a tester you can get at a parts store, and some stores will allow you to borrow the tool. You simply allow the engine to cool, then safely remove the radiator cap, and test the gas inside the radiator. If the liquid in the tester turns color (to yellow), you've got a leak. Finding it usually involves removing the head, a big job. Good luck!
Thank You for the response. I am not looking forward it. I have completed this before with other vehicles that seamed much easy just by the number of things removed.. Again Thank You.
spelunkerd, how's it going, so I've got a 1999 dodge ram 5.9 v8 4x4, when I check the oil with a cold engine it says zero, when I check it with the engine warmed up it says over the max amount.the oil pressure is at 40, I use mobel 1 10w30. it has been recently idling funny when in park it wants to shut off and has a small ping. I put seafoam into the gas and and the engine about 2 weeks ago could the seafoam have caused a problem? or what could the problem be?
+Stevo Nichols Hi Steve. I've never seen that before, although trans oil can show opposite findings when comparing running level to cold. I'd check the PCV valve, look for a vacuum leak and probably check compression to look for huge blowby. It would be wise to change out the oil and filter right away, and drain any seafoam that might be diluting the oil. I'd be checking if you've ever had the plenum pan replaced (replacement pan is nonmagnetic aluminum which is accessed through the throttle body). The most trustworthy readings are with engine cold, which is concerning.... Briansmobile1 did a recent video of an ATV which had a similar complex problem of fuel diluting oil -- watch his video.
+Stevo Nichols That's really odd. I might would have said that the oil drains in the cylinder heads could be clogged. That would mean that your results should be opposite, tho. Did you ever find out what the issue was?
Got a 5.7 hemi in a 07 Jeep Commander Overland. No oil leaks, motor seems pretty clean for 133,00. My oil keeps disappearing. Any ideas?
You're likely using synthetic oil in a newer vehicle, and they tend to have higher consumption since they more easily pass by rings into the combustion chamber. There are not a lot of other places the oil could be going without finding evidence elsewhere.
spelunkerd I use amsoil synthetic
I've got a 96 dodge ram with a V6 and rough idle. Saw your video and its interesting. I believe a small vacuum leak may not show up in a high mileage engine with some blow-by. The smoke machine may work if you take the rockers off in order to close all the valves, so you can build a little smoke pressure. Even with that, the smoke has got to make it out of the crank case. A bad IAC to produce and unacceptable idle. been there and replaced it and it fixed the really bad idle, but not the rough idle. I've replaced all the injectors too.
Ignition problems are fairly common with these trucks. In my videos on the Picoscope I show how a labscope can uncover a problem with a plug, wire, distributor, or coil. Make sure your wire routing is correct, there is a TSB out on the Gen II Rams of that era describing how even a slight variance in wire routing can cause issues. A relative compression test might show something, too. Worth a look....
@@spelunkerd I probably should replace the wires with spiral cores wires. I'll look up your labs cope video.
I have a 98 Dodge 1500 with the 5.2 engine using about 1 quart of oil every 2 to 3 weeks, engine pinging and about 10mpg so I am thinking that I might have the plenum gasket leak. I saw the aluminum plate solution and the intake manifold swap solution but I am wondering if a regular performance intake manifold would also cure the solution instead of the other options? I cannot do the work myself due to many reasons and was thinking that the performance intake swap would be easy and fast for a shop to do, what do you think? Thanks.
Not sure. As I've gotten older I've strayed away from performance engine modifications. If I clearly diagnosed a bad plenum pan gasket I would fix that alone. In your case you need to verify that the oil loss isn't something more serious (like worn rings), so I'd do a compression test first before investing much in the engine.
The Hughes Airgap is a great option and has proven results. That's all I can think of that's readily available and pretty much bolt-on though. Both of the M1 intakes are still on backorder indefinitely and hard to find. Replacing the plenum gasket isn't too difficult, heck, making your own plenum plate isn't hard either. Grab some 1/8in aluminum, cut, and drill.
I bought the Hughes plate, plugs, wires, cap, rotor and thermostat. I paid a mechanic to do the work but I ended up helping to get it done faster. The plenum gasket was gone in 2 places. Once everything was back together the parts made a big difference, I am very glad that I did it. I ask other mechanics if they have heard about this issue, most have not heard about it but some have. Between changing out everything it took about 6 hours more or less. If I ever buy another Dodge truck with the 5.2 or 5.9 engine I will have this done to it just in case. No more oil burning at all now. Thanks for the information.
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thank you . what kind of pressure gauge was that?
Generic gauge, works but nothing fancy.
I had a similar issue where I thought my plenum pan had failed. I was getting rough idle and sometimes a complete stall. I have a manual transmission and whenever I would push in the clutch to the floor the rpms would fall below normal idle and stall out unless I tap the gas while its falling to prevent the stall. I later realized the cause of this was not the plenum after replacing it with the hughes fix kit. The actual cause was a failed egr valve that was stuck open.
Diagnosis is always the most challenging part of auto repair, sometimes difficult even for guys who do it every day. I get the feeling that pan gasket troubles got blamed for many issues through the years, though objective testing often failed to confirm the air leak. A sticking open EGR valve is one of those things that often doesn't come to mind, thanks for your contribution to the thread!
@@spelunkerd You are welcome! Thankyou for the videos.
Any advice would be greatly appreciated. 2002 ram 1500 5.9 360. 141,000 miles. cylinder 5 misfire. Truck did have simptoms of misfire while in idle. Replaced all ignition parts. New plugs, wires, cap, rotor, and coil. Truck ran fine and next day cylinder 5 misfire again engine was misfiring. Took to mechanic that was recommended by friend he checked fuel pressure, injectors those were fine. He also checked compression on cylinder 5 he said it was kind of low 130 he said it should be around 160. He said most likely it needs a valve job. I need to fix this but I can't just do a valve job don't have money to spend what if that's not the problem I guess I just need proof. I'm just trying to see if anyone has had this problem all suggestions are welcome and appreciated and thanks.
You will get more attention at a forum, such as one of the dodge specific forums. One of my favourites is Ericthecarguydotcom. I would be putting the vehicle on a labscope, to try and better define what's going on in that cylinder. Leaking rings require a mechanical solution but it might be reasonable to try a higher weight, natural oil. Good luck!
RBTURBINA1 the proof is right in front of you. You already replaced everything else and you have low compression. Did you check compression in at least another cylinder or two? I've heard of Compression being as high as 245, but that can have to do w the gauge being off on the tester too. Also if your battery is getting low from testing all these cylinders at least 5 cranks that will give lower readings. Or if the throttle isn't opened all the way when you test. Also maybe overkill but did you check your spark plug gap? #5 could of got pinched closely together. You could do a leak down test. easy, look it up. That will help give proof that compression is getting past the cylinder walls via bad piston ring, or scaring of the walls. Also if any debris got in the spark plug hole that could cause the scaring of the cylinder walls, thus why it was working fine, then the next day it isn't. :( because you fixed the original problem, but created a bigger problem in the process by rushing and cutting seemingly minor corners...
RBTURBINA1 one more thing, if your valve seals are in their early stages of falling apart(just rubber seals) then you can use a oil leak stopper to swell the seals. (basically just salt from what I hear, but don't hold me to it) That is only a temporary fix, and I am Leary of mechanics in a bottle and the whole psychology behind the concept of their existence.
Usually poor people(middle to low class, me included) buy them that already have car problems. poor people can't afford attorneys or generally have the time and knowhow to fight if the product totally destroys or makes their vehicle worse and they have more pressing issues like they are out of a vehicle and just too many little daily battles to survive, let alone take on a corrupt big business and there is the fact that the car was breaking down and maybe it getting worse had nothing to do with the product. If I was a POS I would market some products like that too, but I know the struggle and don't want to add to it.
I have a problem with my 97 Dakota sport 3.9 2wd 5spd. It idles a little bit low sometimes (650rpm), and will eventually show the check gauges light and the oil pressure drops to 0. This always occurs at a stop. As soon as you give it some gas it is fine again. I run 10w30 synthetic blend oil. It goes through a quart of oil every 200 miles but doesn't leak. I also only get about 200-240 miles to a tank of gas (mixed highway/city).
I checked and cleaned the pcv valve and it rattles nice, it was a little gummy but not bad. Nothing improved. It runs and drives as well as can be expected for the mileage and I have put a lot of money into the truck and would like to keep it going. Do you think this is the intake manifold gasket? Also, I have read something about a "belly pan gasket" is that the same thing, or something different?
Also, I am not getting any blue smoke. It has a little misfire every now and then usually between 2nd and 3rd gear or when the RPMs are dropping after shifting to neutral from 45+ mph. Sometimes when engine braking is will give a little backfire pop also. My passenger side exhaust manifold flange is shot to it has a pretty severe exhaust leak, not sure if this could be the reason I hear the pops or if it is another symptom of my oil burning / poor gas mileage problem?
Any hints, tips or suggestions of what I should look at? Thanks in advance! Love your channel btw :)
+Nathan Ryan Since the oil pump is driven by engine rotation it's not rare for the oil pressure light to come on with low rpm. I've sometimes wondered if synthetic oil might make that worse because it has slightly lower viscosity, especially when cold. ie when peripheral resistance falls from less viscous oil, pressure will fall as well. However in your case clearly the issue is the low idle speed, and fixing that will resolve most problems. The two commonest causes of low idle are a bad or dirty IAC valve or a vacuum leak. In your case you have an engine that is prone to vac leak through the plenum pan, and you already have oil consumption. While cleaning the IAC and throttle body I would have a look at the plenum pan and put a magnet on it to see if it has already been repaired (OEM pan is steel, Hughes replacement usually aluminum). Also I would do the Chrysler authorized test for vacuum in the crankcase that I showed in another video, although I don't believe the test is completely reliable. Certainly if there is vacuum in the crankcase you need a new pan gasket, but any source of vacuum leak could present in the same way. In an older vehicle like this I would also do a compression test in case your oil consumption may be from bad rings, in which case you have bigger issues. Good luck!
Thank you so much for the fast and thoughtful response :) I will give the IAC and throttle body a good cleaning today and try the magnet test you suggested. I'm willing to bet it is the stock one though. As a temporary fix until I hunt down the actual source of the oil burning do you think maybe I should throw in a quart or 2 of some 20w50 or maybe some Lucas oil stabilizer to thicken things up a bit and see if that helps? And as for the compression test, if I do a dry run to get readings and then do it again with a little oil in the cylinders and the pressure goes up it means the rings are bad right?
+Nathan Ryan I would probably just switch to natural oil at the next oil change. Yes oil in the cylinder will usually increase compression if the leak is from bad rings.
Thanks spelunkerd
Excellent video.
This one is defiantly leaking! Dodge Magnum intake pan gasket leak
Defiantly? Kick it's ass, punish it into submission! :-D
Your PCV system is arranged opposite of mine. I have a hose coming from the left valve cover gasket in to the top of the air box, and on the right I have a hose coming from the valve cover gasket into the side of the intake manifold. My truck is a 2001 but I've had a 99 in the past that was the same as mine. I wonder why the difference on the 98? I'm going to do this test soon and regardless of the result I am installing a Hughes-Edelbrock MPI Air Gap manifold in place of the stock kegger. I still haven't tracked down the rough idle but I would be surprised if the plenum gasket is intact. I also intend to test the 02's and probably will replace the cat on general principle. I have read that the stock catalyst on these trucks is especially restrictive and I am told that an aftermarket high-flow unit is worth a couple miles per gallon.
That's worth exploring, and videorecording your effort. Lots of people are interested in these trucks -- they seem to be a favorite for people who like to tinker with their vehicles. I would certainly be interested in what you do.
That's interesting to see the difference between yours and mine. I don't think it makes a big difference, since the block is mostly symmetrical. But for the test you need to be sure of which one you use to measure manifold vacuum -- one connects above the throttle butterfly, one below.
spelunkerd I learned to drive in the '99 with 265k miles on the clock so the 2nd gen body style Rams will always be special to me. It's a big plus that even if they aren't running properly they seem to keep going. The only downside to them in my opinion is the fuel economy, but it's a truck and you should know what you're getting yourself into if you buy one these days. I'll admit I am intimidated by the intake swap because it's the largest repair I'll have done myself up to this point. The truck is my secondary vehicle so the amount of time that it takes me is not too much of an issue, I'm just worried that I'll mess it up somehow. I intend to complement the new intake with a TB+IAC cleaning, a new filter setup, and a complete ignition tune-up as well. I've never really made a video before but if I can find a place to put my phone such as it will record what I'm doing, I'll try it out. I expect to do the repair in less than a month's time. Only thing holding me back right now is the expense of the intake.
That sounds exciting, I'll be interested to hear how it works out.