Catching this video 2 years later. I'm now confident that I'm not wasting my time on replacing the intake gaskets to solve my vacuum leak. Thanks for the tips, I'm off to do the job right now.
That's exactly what I did on my '89 Chevy Caprice. It has a 305 under the hood. I had to put a new set of intake manifold gaskets on it. Because I heard a load hissing noise while the engine was running. After doing all that, I started it, and no more hissing noise. Good vid BTW.
Another great educational video, Mark. That's too bad about the shoddy work that engine builder did on your 350. Keep the awesome video's coming... I'm learning a lot.
I chased this very problem on a 440 that I put into a Dodge Diplomat. Obviously, the engine and heads were decades old. Minor pitting. It went together and ran good.....for a while then the misfires and backfiring began. It gave me the classic symptoms of either lean or ignition. I am good at tracking down vacuum leaks, but couldn't find one so went through my ignition system several times. I even thought it was rich for a while, but no smoke. I had the carb apart a few times. A few carbs. Mostly Carters. A few distributors. I worked this car like a top fuel team. I would do burnouts (and stall the car). and pull the plugs, clean them off, re-jet it then do it again and put the car in the garage until the police quit coming by. I looked at the plugs, and they were a bit fouled except 7, which nearly looked perfect... because it got more air than the others. I had recently jetted it really rich to see what would happen. So 7 was the only one running right, in theory. Like it was pulling air at that corner. 7 was missing by now, it had got worse, I used a temp gun and 7 was cold. For shits and giggles I had some really lean jets in it now and 7 was really lean and wouldn't fire. I pulled the intake and there was minor pitting right by 7on the head. Not crazy, but some RTV could have cured this, and I used to use RTV but I was very light on the RTV on this one. This engine was one of those deals where you use a valley tin pan too. I only used it around the water ports. It sucked re-doing the intake, but I did a thin film of RTV and that cured it! Under side leaks are very over looked because people will redo the intake and it solves it, or they replace the intake and happen to get it right when they put on a new intake and blame the old intake.
It can be very frustrating when trying to troubleshoot a rough idle situation. I spray carb cleaner around the intake and didn't get any indication of a vacuum leak so I just assumed it good on the underneath side too. It wasn't until I pulled the intake and then I could see the oil leaking past the bottom of the gasket. After fixing that problem, I had other issues with the heads so I scrapped the engine and started over with a new short block, Edelbrock aluminum heads and intake. I also installed a Holley Sniper EFI.
On a stock intake like yours that fel pro set really works, when you go to an aluminum intake on iron heads you need one that is thicker and I've definitely used silicone on coolant passages when the head has pitting or imperfections.
Any engine builder worth his salt will tell you the first thing you do is toss those rubber end gaskets in the garbage !! The best way is to seal the ends with a good RTV gasket sealer 1/4 " bead all along and extra on the ends. Drop your intake on properly and it will never leak
So about 13" Hg, a little bit bouncy on the vac needle? Same here on my C2 with a 350. And I can see a bit of black paper gasket peeking out under the intake, Engine runs fine, jumps when you hit the gas. But I am starting to suspect that gasket. I'll check my plugs.
Another great video. I am restoring my 69 and a lot of the stuff you talk about, I didn’t know. One thing though, pictures are much better than talking if you can show on a video how you checked for the vacuum leak (obviously without taking it apart again). The part where you “talk” about the PCV Valve. Thanks again and look forward to your next video to track down this miss.
I will do a short video on how to check for a vacuum leak in the intake manifold in the near future. I recently purchased new editing software and I am still learning how to use it. I will try to start adding still photos in my videos to help show some of the things better. Thanks for watching.
Recently replaced my intake gasket, and I had scene several videos on how to do it, and a couple videos mentioned that the two center ports (Edlebrock performer RPM high rise) are better to be blocked off entirely. And one person even cut two little rectangles from an old license plate to block them off. I was able to get a “Mr. Gasket” manifold gasket that already had the two ports deleted for the same purpose. Unfortunately I also noticed that the majority of the videos on this subject also recommend that you do not use the rubber gaskets on the china walls and just use the black permatex. But I think the intake gasket has let go because while I was driving through the city I had a mild exhaust back fire and then my throttle was wide open and the linkage is completely normal, but I have oil in it bolt pockets in the passenger side of the intake manifold. Not much but it wasn’t there before
One time when working on a v6 dodge Dakota i found that the heads had been overmachined causing the angle of the intake surface to be too great. Intake leaked internally as a result
I would be furious. That is such a stupid mistake. A good quality gasket isn't expensive. I love that part where you started the car to get the distributor to drop down!! Awesome.
Thanks. I definitely learned my lesson when it comes to finding a good engine builder. From now on I will be buying a long block assembly. That is if I ever need another engine. My goal is to never need another engine. LOL
You ever get told you sound a lot like Hank Hill? lol Excellent video, very informative on installation process. I am assuming this process is the same for all superficial gaskets on the engine? Valve covers, timing cover, etc?
Great video! I just bought a 69 Corvette with a mostly stock 350. There is some wetness near where the intake manifold meets the head right near the carb on both sides, which I thought was a leaky carb so I repainted the warn off paint and I noticed some small bubbling at the interface so I think that there could be a problem with the intake gasket. When I added some coolant (it was low), I also noticed a misfire, which I did not before. I am thinking about testing the coolant tomorrow for exhaust gases. Did you do this test and did it show anything? Any other tips you can share so I can move forward? Thank you!
Update: Good news, fluid stayed blue in tester so no exhaust gas in coolant. After running, I tried painting in a different area where there was no gasket and also saw bubbles on the manifold so sorry for the confusion. That paint must have a low boiling point. The gas I saw was from where the gas line enters the carb (just rebuilt the Quadrajet) so hopefully that leak is fixed after tightening. I will try spraying around the intake just to make sure there is no leak in that area. Also, after further inspection, I don't think that there is a misfire. I just heard some popping out of one of the exhaust, but seems better today. Maybe from my idle mixture screw adjustments. Thanks.
No, I never tested my coolant. I did not appear to have an issue with the intake leaking at the coolant passages. IF you are leaking at the intake, that could cause a vacuum leak which can cause a miss. With the engine running you can spray a little carb cleaner around the carb base and along the intakes where they meet the heads. It the engine RPMs increase the carb or intake is leaking. Be very careful to keep the carb cleaner away from electrical and exhaust manifolds to prevent a fire.
Your videos are very informative and I like how you record your entire process. I did notice that your vacuum fitting on the manifold has two ports. The one on my '72 has one port. Is the additional port because your car originally was an automatic?
Different years used different fittings. Some only had one outlet while others have multiple outlets. My modulator valve was connected to one of the ports and the vacuum system for the headlights, heater and wiper door was connected to the other one. Thanks for your kind words and for watching our videos.
Can a bad intake gasket cause my coolant mix with my engine oil? I notcied yesterday my engine oil is milky and my coolant is now low in the radiator. My engine oil dip stick is showing way passed full now.
That may be a either a bad intake gasket, head gasket, cracked block or cracked head you'll just have to look and see. Don't hold my words against me I'm not a professional by no means I'm just a 18 year old kid that likes messing with motors
i usually use rtv on china walls good bead but my felpro gaskets didnt come with china wall gaskets and i usually put just a finger thin layer on coolant ports on intake and head side just barely a thin layer but thats because my motor is 33 years just added protection
I have a Ford Cleveland 351with a vacuum leak with 2-3 inches of vacuum at the valve cover. Taking the manifold off now as must be leaking into crankcase. No other potential source of leak as not leaking above the manifold.
If you have your pvc valve removed from the valve cover and you still have vacuum from the valve cover instead of pressure, then I would suspect the intake is leaking inside the rocker valley.
there's a reason why people don't use the rubber gaskets on the china walls, I haven't used them in the last 20ish years, you don't even get them with a gasket set for the TBI engines, you get a tube of rtv and instructions state to use that on china walls.
I realize this is an older video now. But I just needed to say, using RTV on the China walks is the correct way. Never use those rubber or cork ones, they WILL leak. I agree with you on the intake gaskets themselves. Throw those china wall gaskets in the trash.
I wish I would have done that. I had trouble with the intake gaskets still leaking after I change them, and I think it was caused by the rubber gaskets not allowing the intake to sit down onto the intake gaskets correctly. I am installing a new short block with an Edelbrock aluminum intake and a Holley Sniper EFI. I did not make the same mistake with the Edelbrock. Thanks for your comments and for watching my videos.
Shoulda used a paper intake gasket like mr gasket set. Rtv on china walls and around coolant ports. Those bulky fel pro intake gaskets suck ass and seal like crap. Now I am a big fan of Fel Pro head gaskets tho.
Catching this video 2 years later. I'm now confident that I'm not wasting my time on replacing the intake gaskets to solve my vacuum leak. Thanks for the tips, I'm off to do the job right now.
@@davidhamm2613 glad to help. Thanks for watching.
Very helpful I am thinking of doing my gaskets on my 80. You are a good mechanic. Thanks Brian
Thanks for watching and the kind words. I really appreciate it.
That's exactly what I did on my '89 Chevy Caprice. It has a 305 under the hood. I had to put a new set of intake manifold gaskets on it. Because I heard a load hissing noise while the engine was running. After doing all that, I started it, and no more hissing noise. Good vid BTW.
@@marcushaynes843 awesome. I’m glad that fixed it.
Another great educational video, Mark. That's too bad about the shoddy work that engine builder did on your 350. Keep the awesome video's coming... I'm learning a lot.
Thanks, will do!
I chased this very problem on a 440 that I put into a Dodge Diplomat. Obviously, the engine and heads were decades old. Minor pitting. It went together and ran good.....for a while then the misfires and backfiring began. It gave me the classic symptoms of either lean or ignition. I am good at tracking down vacuum leaks, but couldn't find one so went through my ignition system several times. I even thought it was rich for a while, but no smoke. I had the carb apart a few times. A few carbs. Mostly Carters. A few distributors. I worked this car like a top fuel team. I would do burnouts (and stall the car). and pull the plugs, clean them off, re-jet it then do it again and put the car in the garage until the police quit coming by. I looked at the plugs, and they were a bit fouled except 7, which nearly looked perfect... because it got more air than the others. I had recently jetted it really rich to see what would happen. So 7 was the only one running right, in theory. Like it was pulling air at that corner. 7 was missing by now, it had got worse, I used a temp gun and 7 was cold. For shits and giggles I had some really lean jets in it now and 7 was really lean and wouldn't fire. I pulled the intake and there was minor pitting right by 7on the head. Not crazy, but some RTV could have cured this, and I used to use RTV but I was very light on the RTV on this one. This engine was one of those deals where you use a valley tin pan too. I only used it around the water ports. It sucked re-doing the intake, but I did a thin film of RTV and that cured it! Under side leaks are very over looked because people will redo the intake and it solves it, or they replace the intake and happen to get it right when they put on a new intake and blame the old intake.
It can be very frustrating when trying to troubleshoot a rough idle situation. I spray carb cleaner around the intake and didn't get any indication of a vacuum leak so I just assumed it good on the underneath side too. It wasn't until I pulled the intake and then I could see the oil leaking past the bottom of the gasket. After fixing that problem, I had other issues with the heads so I scrapped the engine and started over with a new short block, Edelbrock aluminum heads and intake. I also installed a Holley Sniper EFI.
On a stock intake like yours that fel pro set really works, when you go to an aluminum intake on iron heads you need one that is thicker and I've definitely used silicone on coolant passages when the head has pitting or imperfections.
I always use Fel Pro gaskets and never had an issue with one leaking. Thanks for watching.
I just had the same problem because I did not want to use any silicone on intake i made bad decision.
What kind of gasket was it for the aluminum to iron
Good troubleshooting info. Glad you did eventually find the issue. Now to find the video of that!
Thanks. Unfortunately, due to other issues with the engine, I ended up replacing it with a brand new short block.
Any engine builder worth his salt will tell you the first thing you do is toss those rubber end gaskets in the garbage !! The best way is to seal the ends with a good RTV gasket sealer 1/4 " bead all along and extra on the ends. Drop your intake on properly and it will never leak
Thanks for this
I’m doing mine this Friday
I hope it went well for you.
So about 13" Hg, a little bit bouncy on the vac needle?
Same here on my C2 with a 350. And I can see a bit of black paper gasket peeking out under the intake, Engine runs fine, jumps when you hit the gas. But I am starting to suspect that gasket. I'll check my plugs.
Another great video. I am restoring my 69 and a lot of the stuff you talk about, I didn’t know. One thing though, pictures are much better than talking if you can show on a video how you checked for the vacuum leak (obviously without taking it apart again). The part where you “talk” about the PCV Valve. Thanks again and look forward to your next video to track down this miss.
I will do a short video on how to check for a vacuum leak in the intake manifold in the near future. I recently purchased new editing software and I am still learning how to use it. I will try to start adding still photos in my videos to help show some of the things better. Thanks for watching.
Recently replaced my intake gasket, and I had scene several videos on how to do it, and a couple videos mentioned that the two center ports (Edlebrock performer RPM high rise) are better to be blocked off entirely. And one person even cut two little rectangles from an old license plate to block them off. I was able to get a
“Mr. Gasket” manifold gasket that already had the two ports deleted for the same purpose. Unfortunately I also noticed that the majority of the videos on this subject also recommend that you do not use the rubber gaskets on the china walls and just use the black permatex. But I think the intake gasket has let go because while I was driving through the city I had a mild exhaust back fire and then my throttle was wide open and the linkage is completely normal, but I have oil in it bolt pockets in the passenger side of the intake manifold. Not much but it wasn’t there before
One time when working on a v6 dodge Dakota i found that the heads had been overmachined causing the angle of the intake surface to be too great. Intake leaked internally as a result
I think that's what happened to my heads too.
I would be furious. That is such a stupid mistake. A good quality gasket isn't expensive. I love that part where you started the car to get the distributor to drop down!! Awesome.
Thanks. I definitely learned my lesson when it comes to finding a good engine builder. From now on I will be buying a long block assembly. That is if I ever need another engine. My goal is to never need another engine. LOL
Very good video. How much force are the screws tightened? Thank you
The intake bolts were torqued to 25 Ft/Lbs
I was wondering about the sequence of torqueing the bolts...any pattern? It looked like he started in the middle.
@@jeffreyelofson533 Yes, it starts in the middle, then the back and finally the front bolts.
Were you getting oil on your plugs due to the intake gasket issue?
yes. I had oil on the plugs.
You ever get told you sound a lot like Hank Hill? lol
Excellent video, very informative on installation process. I am assuming this process is the same for all superficial gaskets on the engine? Valve covers, timing cover, etc?
Thank you. Information about vacuum informative.
Thanks for watching and commenting.
Great video! I just bought a 69 Corvette with a mostly stock 350. There is some wetness near where the intake manifold meets the head right near the carb on both sides, which I thought was a leaky carb so I repainted the warn off paint and I noticed some small bubbling at the interface so I think that there could be a problem with the intake gasket. When I added some coolant (it was low), I also noticed a misfire, which I did not before. I am thinking about testing the coolant tomorrow for exhaust gases. Did you do this test and did it show anything? Any other tips you can share so I can move forward? Thank you!
Update: Good news, fluid stayed blue in tester so no exhaust gas in coolant. After running, I tried painting in a different area where there was no gasket and also saw bubbles on the manifold so sorry for the confusion. That paint must have a low boiling point. The gas I saw was from where the gas line enters the carb (just rebuilt the Quadrajet) so hopefully that leak is fixed after tightening. I will try spraying around the intake just to make sure there is no leak in that area. Also, after further inspection, I don't think that there is a misfire. I just heard some popping out of one of the exhaust, but seems better today. Maybe from my idle mixture screw adjustments. Thanks.
No, I never tested my coolant. I did not appear to have an issue with the intake leaking at the coolant passages. IF you are leaking at the intake, that could cause a vacuum leak which can cause a miss. With the engine running you can spray a little carb cleaner around the carb base and along the intakes where they meet the heads. It the engine RPMs increase the carb or intake is leaking. Be very careful to keep the carb cleaner away from electrical and exhaust manifolds to prevent a fire.
Your videos are very informative and I like how you record your entire process. I did notice that your vacuum fitting on the manifold has two ports. The one on my '72 has one port. Is the additional port because your car originally was an automatic?
Different years used different fittings. Some only had one outlet while others have multiple outlets. My modulator valve was connected to one of the ports and the vacuum system for the headlights, heater and wiper door was connected to the other one. Thanks for your kind words and for watching our videos.
Do you have to use sealer if u use the gasket (the wall)
You will still need to put sealer at each end of the wall where the block and heads come together.
very nice to watch and learn
Can a bad intake gasket cause my coolant mix with my engine oil? I notcied yesterday my engine oil is milky and my coolant is now low in the radiator. My engine oil dip stick is showing way passed full now.
That may be a either a bad intake gasket, head gasket, cracked block or cracked head you'll just have to look and see. Don't hold my words against me I'm not a professional by no means I'm just a 18 year old kid that likes messing with motors
@@boostedmonster6363 I believe it was my gaskets. I just replaced my intake and head gaskets. Didnt see any warped head and the block looked good.
Yes it can. I'm watching this video now because I had that exact problem. Coolant gets out of those ports in the intake and goes down into the valley
@@ilsmawandfarm1767 I actually fixed it already and installed new intake Fel pro gaskets .
@armygreenfj3924 I figured you did, I'm just leaving this here for if someone else has the same problem
What's are the bolts torqued too?
For cast iron heads the torque spec is 30ft/lbs. and aluminum heads is 25ft/lbs.
Can bad intake gaskets cause a rich idle?
Normally that would cause the car to run rough and lean because you would be sucking air in past the gaskets.
i usually use rtv on china walls good bead but my felpro gaskets didnt come with china wall gaskets and i usually put just a finger thin layer on coolant ports on intake and head side just barely a thin layer but thats because my motor is 33 years just added protection
they dont give enough so i bought 90 minute black i like black because it looks cleaner
Sounds like a good idea. Thanks
I have a Ford Cleveland 351with a vacuum leak with 2-3 inches of vacuum at the valve cover. Taking the manifold off now as must be leaking into crankcase. No other potential source of leak as not leaking above the manifold.
If you have your pvc valve removed from the valve cover and you still have vacuum from the valve cover instead of pressure, then I would suspect the intake is leaking inside the rocker valley.
What was causing the miss?
I think it was the intake leaking but I'm not sure. I found several issues with the motor, all of which could of had some impact on the miss.
Good video helpful information
Thanks for watching
there's a reason why people don't use the rubber gaskets on the china walls, I haven't used them in the last 20ish years, you don't even get them with a gasket set for the TBI engines, you get a tube of rtv and instructions state to use that on china walls.
I realize this is an older video now. But I just needed to say, using RTV on the China walks is the correct way. Never use those rubber or cork ones, they WILL leak. I agree with you on the intake gaskets themselves. Throw those china wall gaskets in the trash.
Yes, I tried to use them once and learned my lesson to never use them again. I don't know why they even supply them in the kit.
GM stopped using them in later years.
Sir I wish I could pay you to swap out my intake manifold and carb on my 86 monte carlo ss.
Do you live in Florida?
@@timewiththedurbins I do, the Jacksonville area.
@@RakMPVet05 I live near Ocala, about 3 hours southwest of Jacksonville.
@@timewiththedurbins how do I get in contact with you?
@@RakMPVet05 my email is: mdurbin57@hotmail.com
After seeing how cheap the builder was with the intake gasket. I hope the bottom end's OK. Sets off the red flags.
I'm not taking any chances. I purchased a new short block to replace it.
@@timewiththedurbins😂
Nice video, just curious, is that the car you got for Diane to use for a work car? Tell everyone hi for me.
Take care, sis 💕
LOL not that's not the car.
thank you
👍
I would have left the china wall rubber gaskets off and used only RTV as did the previous assembler.
I wish I would have done that. I had trouble with the intake gaskets still leaking after I change them, and I think it was caused by the rubber gaskets not allowing the intake to sit down onto the intake gaskets correctly. I am installing a new short block with an Edelbrock aluminum intake and a Holley Sniper EFI. I did not make the same mistake with the Edelbrock. Thanks for your comments and for watching my videos.
Definitely missed water ports with silicone
I normally don't use silicone in those areas when I use Fel Pro gaskets. I have never had an issue with coolant leakage.
Never use rubber in silicone together
Shoulda used a paper intake gasket like mr gasket set. Rtv on china walls and around coolant ports. Those bulky fel pro intake gaskets suck ass and seal like crap. Now I am a big fan of Fel Pro head gaskets tho.
I have never had an issue with Fel Pro gaskets. I guess if we all used the same thing the world would be a boring place.
Don't use those rubber gaskets on the China wall! You bead up RTV
When I installed my Edelbrock heads and intake, I did not use the rubber gaskets.
Can’t trust anyone. Shops today.
You definitely want to check a shop out before you use them.