Alright dude i have a few things to add because you may be leading some people astray. Like me. So first of all your vacuum reading depends entirely on your Barometric Pressure/Elevation. At or close to sea level you should see a vacuum of 17-22 in/Hg. That number decreases as you go up in altitude (down in barometeric pressure). So at 3-4 thousand feet you should see a vacuum of 15-19 in/Hg. I am at 7,000 ft above sea level, my Vacuum should read 12-16 in/Hg. Keep in mind that Idle vacuum for most engines is about 18-22 in/Hg AT SEA LEVEL but some may produce only 15-17 inches idle depending on your motor. you need to refer to your cars repair manual for vacuum specs. If your valve timing is retarded, the needle on the guage will bounce due to blow by on the intake valves back into the manifold........ not a steady low pressure reading on the gauge. Under load your Vacuum should be zero at cruising speed thats how you know you have a healthy motor.
Great point Josh! What is the formula for determining vacuum at various elevations? I'm at 5K ft. here in Colorado maybe it should be between 13-18 In/Hg?
Nope, at full throttle on a gasoline engine the vacuum will be at or near (filters have some restriction) 0. any time you're not flooring it, that throttle valve is closing in order to create a partial vacuum in the intake manifold (this is how your car restricts the amount of air it ingests).
Good trivial point, if using an actual mercury gauge (which almost no one owns) which measures pressure differential. But not at all related to this regardless of gauge. Please note that there is an acceptable range. This covers pressure differences. Please also consider that the external pressure will have no effect on fluctuations or trends, which are what we look for in diagnostics.
I am fully trained auto and diesel mechanic, since I started repairing cars and trucks especially gasoline engines I use vacuum gauge for diagnosing engine troubles.I appreciate your excellent demonstration.
This is by far the most simple to the point video that was so helpful and educational! Thank u for making this video and hope more people pay attention to your open your mind video.. thanks
Just purchased this gauge to check vacuum and fuel pressure wow so helpful it all makes sense but you don't think about it until someone tells you, great video mate
This is the exact thing I was looking for great video IAM a Old school mechanic and a lot of New mechanic do do this kind of diagnostics but I am learning really fast about it THANK YOU GOD BLESS
That sound like providing food, when your're thirsty! LOL 😂 All in all very nice but don't fulfill the necessary requirements. Compression test, leak down test, vacuum test. They all have a place and time to be done and work as complements rather than substitutions of each other! Cheers
Dude, I do love your explanations here on what can be seen with such a guage when you know how to read it and what the reading means. It's crazy how very few mechanic just don't the easy steps to properly diagnostise an engine with the proper tools to fix the right thing once and for all. Same goes with multimeters and voltage drops across the starter, block or alternator cables. I've seen stupid mechanic screaming after the parts guy that his last 3 starters were worn and a bad connection that couldn't be seen bared eyes was the problem of slow cranking... again, i can't wait to get a hand on a vacuu, gauge and fix my engines myself better. thanks a lot for this helpful video
Nice video about probably the most forgot and underrated cheap tool to have in your tool bag. Most nowadays think it's not worth because it lacks blinking lights or a PC attached. LOL ;-) Thumbs up
forgot most important step - what cam do you have? stock/stage 1 this would apply, but id drop 2-3 inches per stage of cam, around stage 3 the readings get more whacky from a bad vac signal. My 288HR comp cam idles 7 inches and very few of these principles apply with radical cams. Id say around 230-240 duration and up things start falling apart.
Me es de mucha utilidad éste video, gracias por compartir tu conocimiento. Recibe fuerte abrazo y saludos desde la ciudad de Tampico Tamaulipas México. Gracias.
I'm having this done today on.my 98 dodge ram 5.9l w/ 187,000 "ticks on the clock." This explains alot for me to know if I need a rebuild or not, thanks!
17 - 20 Hg's for an engine with a stock OEM cam. If you have a more radical cam vacuum will be lower. In my case with a .610 lift my vacuum reads around 13 Hg's at idle then drops to 0 at high RPM.
Great video. There's a lot to remember- there was a mistake. This it critical so perhaps have the info written down to refer to in the future. Good though.
awesome awesome awesome video !!! Ignore any naysayers. Anyone can be a critic (really? I should account for barometric pressure? How about humidity? How about durometer rating of the line? Sheesh) I have a 1966 Mustang 289 4 barrel and I get good vacuum but have that very fast small fluctuation. SO not sure if its valve seals or as you pointed out to someone else, new, so don't worry...BUT ...changing to aluminum heads soon so I will worry then...thanks for a great video
Nice video thanks. I'm weighing a valve adjustment on my Sentra B15 because of low acceleration chatter - I'll see if I can get any clues w/ this Harbor Freight tool tomorrow. By the way, I've been able to thread the hose under the hood and place the gauge on the windshield so that I can view it when performing snap-throttle. If it''s too short for your location just go to the auto parts store and buy a 2' section of comparable vacuum line (take the original for comparison).
Good video. I have the symptoms of an exhaust obstruction. Strong 20 inches, then as I throttle up (in park, no load) it starts to sputter and loses vacuum. It a simple v8, Oldsmobile 307 but it been troublesome. I’ve been through multiple sets of plug/ wires and distributors. New fuel pump filter even overhauled the motor. I guess I’m gonna check the fuel pressure tomorrow . Oh and I have no exhaust restriction. But maybe I have carburetor problems. I don’t know what else it could be.
Hi Matt, fantatic video! Been watching several videos: all articulately explained and videod (not easy to do). I have the feeling that if I keep watching, I could be a professional. Good job! God bless!
Great video Mat Motorz, thanks. Josh Arbour, I presume pressure gauge shown measures relative pressure(1), therefore altitude of engine is irrelevant for this analysis. (1) pressure gauge indicates zero when not connected at all altitudes
Lets do some math on this. At sea level atmosferic pressure will be 100 kpa or 29.9 in Hg. We can asume we live in a city at an altitude of 4000mts Over sea level. Over there armosferic pressure will be little more than 60k Kpa equivalent to 18 in Hg. With 18 in of armosferic pressure how can you get 22 in of vacumm. I believe Josh is right.
Vacuum guage and stethoscope.. two of the simplest but most useful tools. Most vacuum gauges come with a piece of paper that outlines these readings also.
Big thanks for the explanation! On my 350 sbc I read at idle a flickering needle on 16hg at 600rpm. Fast idle 1200rpm and the needle is steady at 19hg. Timing is late 8 degree. I think it‘s a mix from bad valve stem seals, that also indicat the blueish puffs after a shifts and a bit more timing mabye 12 degree? Thanks
hi, i was hoping you could help me with the readings i got from my little mazda truck 2bbl. the needle from my vac gauge reads in between 15 and 18 unsteady. i could never get it to hit 20 in of mercury. when i rev it up, it would go back to 0 and then goes to 20 and then back to 15-18.
I have an error code that shows a mass air flow issue, which could be the sensor which is very expensive ( I already cleaned this) but I guess having seen this video it could also be a blockage in the exhaust. Also to me the exhaust from the car is not a normal diesel smell. Great video very informative.
Hi, thanks for the video. I bought this equipment to diognose potential problems on my Passat B5 TDİ 1.9 AFN engine. My problem is I want to learn the right spot to connect the equipment on my engine. Can you help me ? By the way, your videos are super🙏
@@MattsMotorz Hey MattsMotorz quick question i did this test on my 2008 Toyota Corolla and the engine idled at little under 20 maybe 17 and when i hit the gas it jumped from 10 to 22 .... what would cause that ? you said it should jump from 0 to 25
@@MattsMotorz When I was checking for an intake leak the result was the needle was hyper fluctuating back and forth 1 point between 19 1/2 and 20 1/2 (a steady 20 is recommened for vehicle) ...this fluctuation is indicating / confirming I have a vacuum leak ...correct?? thanks.
Superb explanation I just learned a lot from this vedio.can you please do a vedio on Dry and Wet Compression test and cylinder leakage testing.if you have time.
How on earth did you get a vacuum reading from that hose after popping it OFF of the intake manifold??? Isn't that it's vacuum source!?! I'm generally confused now...
Alright dude i have a few things to add because you may be leading some people astray. Like me. So first of all your vacuum reading depends entirely on your Barometric Pressure/Elevation. At or close to sea level you should see a vacuum of 17-22 in/Hg. That number decreases as you go up in altitude (down in barometeric pressure). So at 3-4 thousand feet you should see a vacuum of 15-19 in/Hg. I am at 7,000 ft above sea level, my Vacuum should read 12-16 in/Hg. Keep in mind that Idle vacuum for most engines is about 18-22 in/Hg AT SEA LEVEL but some may produce only 15-17 inches idle depending on your motor. you need to refer to your cars repair manual for vacuum specs. If your valve timing is retarded, the needle on the guage will bounce due to blow by on the intake valves back into the manifold........ not a steady low pressure reading on the gauge. Under load your Vacuum should be zero at cruising speed thats how you know you have a healthy motor.
and the sentor MAP? what values this take?
Great point Josh! What is the formula for determining vacuum at various elevations? I'm at 5K ft. here in Colorado maybe it should be between 13-18 In/Hg?
Nope, at full throttle on a gasoline engine the vacuum will be at or near (filters have some restriction) 0. any time you're not flooring it, that throttle valve is closing in order to create a partial vacuum in the intake manifold (this is how your car restricts the amount of air it ingests).
@Andre Woods Advance Challenged maybe?
Good trivial point, if using an actual mercury gauge (which almost no one owns) which measures pressure differential. But not at all related to this regardless of gauge. Please note that there is an acceptable range. This covers pressure differences. Please also consider that the external pressure will have no effect on fluctuations or trends, which are what we look for in diagnostics.
I’ve spent 1+ hours trying to find a video of WHERE (and how) to hook up the vacuum gauge to, and you finally answered my question! THANK YOU!!!
I am fully trained auto and diesel mechanic, since I started repairing cars and trucks especially gasoline engines I use vacuum gauge for diagnosing engine troubles.I appreciate your excellent demonstration.
Awesome! Thanks for the comment.
This is by far the most simple to the point video that was so helpful and educational! Thank u for making this video and hope more people pay attention to your open your mind video.. thanks
Great video! I bought one of these gauges over 20 years ago but never really used it. Amazing what stories these gauges can tell.
Just purchased this gauge to check vacuum and fuel pressure wow so helpful it all makes sense but you don't think about it until someone tells you, great video mate
Exactly what I needed to see before heading back out tomorrow. Thanks
This is the exact thing I was looking for great video IAM a Old school mechanic and a lot of New mechanic do do this kind of diagnostics but I am learning really fast about it THANK YOU GOD BLESS
great video, very well explained. I've just ordered one and now wonder why in 30 years of car tinkering I've never had one before
Vintage Steel same here should have bought one years ago. Very inexpensive tool to have.
Wow dude, did anyone tell you that you sound like Garth from "Waynes world"......Excellent video.
Very good! Such a simple tool yet often overlooked and one of the most useful in the arsenal!
very informational. Doing a vacuum test seems alot easier than doing a compression test since sometimes the spark plugs are hard to get to
That sound like providing food, when your're thirsty! LOL 😂 All in all very nice but don't fulfill the necessary requirements. Compression test, leak down test, vacuum test. They all have a place and time to be done and work as complements rather than substitutions of each other! Cheers
Dear sir.ive just found this video.absolutety superb.very clear.
This has helped me loads.stevevfrom the uk.
Well damn if everything you claim is true then I have no reason to believe it's not This is a gold mine of info man I really do appreciate it
Dude, I do love your explanations here on what can be seen with such a guage when you know how to read it and what the reading means. It's crazy how very few mechanic just don't the easy steps to properly diagnostise an engine with the proper tools to fix the right thing once and for all. Same goes with multimeters and voltage drops across the starter, block or alternator cables. I've seen stupid mechanic screaming after the parts guy that his last 3 starters were worn and a bad connection that couldn't be seen bared eyes was the problem of slow cranking... again, i can't wait to get a hand on a vacuu, gauge and fix my engines myself better. thanks a lot for this helpful video
Thanks for very useful video. Every do it your self mechanic should have a vaccum gauge. Is this the civiv engine in the car?
Clear and to the point. I have a 55 side valve british truck. I'll buy one of these gauges.
Great job. I really like how you explain how to read the vacuum gauge for different kind of engine problems. Thanks
Excellent video! This was a comprehensive explanation on how to use intake manifold pressure readings to identify engine issues.
Yeah but did he have to tap into the other end where he pulled the line off? I can't find where to try this on my 4.6
Nice video about probably the most forgot and underrated cheap tool to have in your tool bag. Most nowadays think it's not worth because it lacks blinking lights or a PC attached. LOL ;-) Thumbs up
forgot most important step - what cam do you have? stock/stage 1 this would apply, but id drop 2-3 inches per stage of cam, around stage 3 the readings get more whacky from a bad vac signal. My 288HR comp cam idles 7 inches and very few of these principles apply with radical cams. Id say around 230-240 duration and up things start falling apart.
Great information!!! has come in handy multiple times!!! Thanks!
Class video, clear and concise with no fluff
Me es de mucha utilidad éste video, gracias por compartir tu conocimiento.
Recibe fuerte abrazo y saludos desde la ciudad de Tampico Tamaulipas México.
Gracias.
dude, I love how you explain things, thank you for taking the time to make the video, you truly have a knack for teaching
+gReGsKi GmAiL Thanks a lot!
Nice video mate, really helpful!
woah
Thank you for making this video. It was very informative and easy to understand ☆
This was very good, thank you. Its amazing the amount of troubleshooting that can be done easily with proper knowledge of this tool.
Thank you for your clear explanations.Also for the captions, which made it easy for me to take notes. Good job!
I'm having this done today on.my 98 dodge ram 5.9l w/ 187,000 "ticks on the clock." This explains alot for me to know if I need a rebuild or not, thanks!
I did some research and found a gauge just like yours at NAPA. Wonderful! Thank you, David 🐈
They have that one at HF for about $13
Amazing what you can tell about an engine from an analog gauge.
Thank You for this video. One of the best I've seen!
Question: Wouldn't not plugging the port on the intake manifold where you take the tube off of, affect readings since it is letting air in/out?
real good vid thanks helps alot with my new engine in my 65 gto
This is simple applicable and totally true
17 - 20 Hg's for an engine with a stock OEM cam. If you have a more radical cam vacuum will be lower. In my case with a .610 lift my vacuum reads around 13 Hg's at idle then drops to 0 at high RPM.
Good video,nice and clear and in plain English,really helpful,thanks.👍
I agree with plain English, thanks also for that. Great job to sharing this
Great video. It changed my life.
Great video. There's a lot to remember- there was a mistake. This it critical so perhaps have the info written down to refer to in the future. Good though.
awesome awesome awesome video !!! Ignore any naysayers. Anyone can be a critic (really? I should account for barometric pressure? How about humidity? How about durometer rating of the line? Sheesh) I have a 1966 Mustang 289 4 barrel and I get good vacuum but have that very fast small fluctuation. SO not sure if its valve seals or as you pointed out to someone else, new, so don't worry...BUT ...changing to aluminum heads soon so I will worry then...thanks for a great video
Nice video thanks. I'm weighing a valve adjustment on my Sentra B15 because of low acceleration chatter - I'll see if I can get any clues w/ this Harbor Freight tool tomorrow. By the way, I've been able to thread the hose under the hood and place the gauge on the windshield so that I can view it when performing snap-throttle. If it''s too short for your location just go to the auto parts store and buy a 2' section of comparable vacuum line (take the original for comparison).
Good video.
I have the symptoms of an exhaust obstruction. Strong 20 inches, then as I throttle up (in park, no load) it starts to sputter and loses vacuum. It a simple v8, Oldsmobile 307 but it been troublesome.
I’ve been through multiple sets of plug/ wires and distributors. New fuel pump filter even overhauled the motor.
I guess I’m gonna check the fuel pressure tomorrow . Oh and I have no exhaust restriction. But maybe I have carburetor problems. I don’t know what else it could be.
Well done ! Good audio, easy graphics, concise script .
Hi Matt, fantatic video! Been watching several videos: all articulately explained and videod (not easy to do). I have the feeling that if I keep watching, I could be a professional. Good job! God bless!
So we just look at a nonmoving gauge and listen to you talk? Great video…
awesome video....very informative ...thanks
Good video that is crazy I didn't know a vacum gauge could tell you all that.
Excellent Vid! I got exactly the info I was looking for. THANKS!
yes, its work on toyota hiace too. I change vaccum pump on 200k km(8 years of use)
Great video Mat Motorz, thanks.
Josh Arbour, I presume pressure gauge shown measures relative pressure(1), therefore altitude of engine is irrelevant for this analysis.
(1) pressure gauge indicates zero when not connected at all altitudes
Lets do some math on this. At sea level atmosferic pressure will be 100 kpa or 29.9 in Hg. We can asume we live in a city at an altitude of 4000mts Over sea level. Over there armosferic pressure will be little more than 60k Kpa equivalent to 18 in Hg. With 18 in of armosferic pressure how can you get 22 in of vacumm. I believe Josh is right.
Excelent ! Thanks for the video !
Vacuum guage and stethoscope.. two of the simplest but most useful tools.
Most vacuum gauges come with a piece of paper that outlines these readings also.
Where does that vacuum line come from
I have a steady 8 in of mercury on my 289. According to your video I have a big vacuum leak right?
Great video Thanks
Thanks a lot for this very important video.
Very use and well explained. Thank you.
Very helpful!
Very helpful!
hey my friend that is a great video I've learned a lot thank you very much
Big thanks for the explanation! On my 350 sbc I read at idle a flickering needle on 16hg at 600rpm. Fast idle 1200rpm and the needle is steady at 19hg. Timing is late 8 degree.
I think it‘s a mix from bad valve stem seals, that also indicat the blueish puffs after a shifts and a bit more timing mabye 12 degree? Thanks
Excellent meticulous tutorial.
Dude! thumbs up for sure on a great video. Keep up the great work.
Helpful information, thank you for sharing !!
Great video, Thanks Matt.
best presentation ive seen
Thanks for very useful video.
This really helped me out, thanks very much
Thanks it helped me a lot
Thanks MattsMotorz. Great video. Very informative. I have a vacuum gauge kit on order from Amazon after your video.
hi, i was hoping you could help me with the readings i got from my little mazda truck 2bbl. the needle from my vac gauge reads in between 15 and 18 unsteady. i could never get it to hit 20 in of mercury. when i rev it up, it would go back to 0 and then goes to 20 and then back to 15-18.
Excellent video!
Thanks for great video. It is useful.
Thank you👍🔧 great video. i just picked up a vacuum gauge.
Very helpful - great explanation!
That was a great video man thanks!
excellent video
Great vidio Matt!!
I have an error code that shows a mass air flow issue, which could be the sensor which is very expensive ( I already cleaned this) but I guess having seen this video it could also be a blockage in the exhaust. Also to me the exhaust from the car is not a normal diesel smell.
Great video very informative.
This video was very helpful.
Hi, thanks for the video. I bought this equipment to diognose potential problems on my Passat B5 TDİ 1.9 AFN engine. My problem is I want to learn the right spot to connect the equipment on my engine. Can you help me ?
By the way, your videos are super🙏
Very helpful. Thanks for taking the time to post this.
Thanks for the info
Good info in plain lingo,nice 1
+james woolley Thanks for watching!
This was just a great video!
Thanks!
Great video....learned a lot today!!! thanks
Finally thanks so much very knowledgeable
very informative Thank you.
Thank you! This is exactly what I've been looking for. Now I just have to look/buy a vacuum gauge.
I subscribed!!!
Thanks for subscribing! I definitely do appreciate that. Glas you liked the video :D
@@MattsMotorz Hey MattsMotorz quick question i did this test on my 2008 Toyota Corolla and the engine idled at little under 20 maybe 17 and when i hit the gas it jumped from 10 to 22 .... what would cause that ? you said it should jump from 0 to 25
@@MattsMotorz When I was checking for an intake leak the result was the needle was hyper fluctuating back and forth 1 point between 19 1/2 and 20 1/2 (a steady 20 is recommened for vehicle) ...this fluctuation is indicating / confirming I have a vacuum leak ...correct?? thanks.
Impressive video explanation
Thanks for a great video! And yes, I "Like" and I subscribed.
I appreciate it! :]
@@MattsMotorz hey Matt, great video. Question, how much vacuum should an engine be pulling, on a crank no start no spark condition?
great video.
Superb explanation I just learned a lot from this vedio.can you please do a vedio on Dry and Wet Compression test and cylinder leakage testing.if you have time.
I have a video on compression testing and leak down testing already.
What does it mean if the needle stops bouncing around after the engine warms up?
really helpful!
Very helpful. Thanks
How on earth did you get a vacuum reading from that hose after popping it OFF of the intake manifold??? Isn't that it's vacuum source!?! I'm generally confused now...
great video man ,thanks for the info very helpful!!!
Good stuff..Thx!
This is great information!