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.
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
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 1970 Boss 429 and at 800 RPM idle the vacuum is steady 3 inch and at about 3000 RPM it has a steady 17 inch. I have a high performance Comp cam in the engine. Engine run great and doesn't have 100 miles sense rebuild. Is this normal?
You need to attach it to something with direct engine vacuum, anything off the cylinder head probably wont be direct engine vacuum. Anything off the intake manifold is a good place to connect to. I like to hook it up to the brake booster line.
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.
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
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.
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
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.
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🙏
Let's see if I can get a response okay I have a Chevy Cruze and the p0011 code has to do with my intake cam problem which the diagnostic said it was the actuator I have changed both intake and exhaust did not fix the problem check engine light still on when I do the vacuum test my engine seems to rev Indy healthy area about 19 2 20 inches of mercury while in idle the needle has a fast vibration and it moves up and down from 18 inches of mercury 2 about 20 and a half inches of mercury so it stays steady in the green healthy area but it is moving back and forward a little bit I'm trying to figure out is something here the cause of my check engine light remain on because the diagnostic mentioned something about timing being off a little I can't really tell everything with the timing chain that I can see lines up to top dead center could this be anything dealing with some valves or Springs
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.
On a fully warmed engine and when I blip the throttle,. my needle drops to zero but then goes straight to 20 and stays steady. It doesn't go to 25 and then slowly settles back down. Do I have an issue?
When your doing these readings. Is it good to turn all Accessories off? Soon as my compressor comes on my readings drop alot? Which seems normal. Am I wrong?
Thanks for the great video! I have a 351M in a 78' F250, that starts to have white smoke after warming up, but not on first starting. After watching your video I bought a gauge and the reading on start up is a vibration between 15-16 and then after warming up, it fluctuates between 6-20. Do you think I have a head gasket leak?
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...
Everything is new in my 68 Mustang, with a crate stock 302, runs well no issues. But the vacuum gauge shows 15. I managed to get 17 after advancing the ign. timing a little. What do you think? Should I advance it further to achieve 18 or more?
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!
Heres a scenario, my engine is at normal in the green area.....but when I rev it really quick to about 3000 rpms the gauge goes up to 25 hg's when i let go of the accelerater, the gauge slowly drops back to normal green area...but it takes at least a minute or 2 in order for it to get there.
Sounds like its starving for air when you open the throttle it allows air in wich is why I drops to zero. If it's pulling higher vaccum at higher rpm would be due to lack of air in the intake.
Hi my trucks been sitting for a year untouched ,diesel Hilux Rebuilt engine ,brake boosters not working but I have a new vacuum pump and it registers at 25-6 very steady inches of mercury (300m above sea level ) I do remember the first day I installed the engine I had brakes only ran it for a couple of minutes next morning nothing ,pedal doesn't move at all when turned on ,is it possible the diaphragm weakened over that time
i have a 1600 british pinto engine am getting a vibrating reading between 13 to 15 which i believe is advanced timing ?? the car runs rich mixture but runs really smooth ( it was set up on a dyno test and it was the only way it would run smooth ( car is now 41years old ) can anyone tell me me can i fit a 7" dual booster -- what i have now is a 8" single and it works fine but the master cylinder has a problem and the parts are non existent so can i fit the 7" with an upgraded master cylinder of 15/16" original is 3/4" but running on single pot calipers but now have 4 pot calipers each side can any of you guys help me solve this problem
steady vibration 1/2 inch between 21 and 21.5...worn valve guide? Its only 1/2 " but the head is very old, new valve seals new head gasket, all valves adjusted.
4:51 ...okay wait, so the declining gauge pressure is a sign of both an exhaust obstruction AND an air leak in the in the intake manifold? also, if you disconnected one of the vacuum hoses, what is plugging up the port that you disconnected it from?
I've herd people using vacuum gauges to correct idle mixture but I can screw my idle mixture screws in all the way until the engine dies and it doesn't effect the vacuum gauge
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.
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
Hi my friend. Is this tool suitable for turbo diesel engine cars? I have a Passat B5 1.9 TDI AFN engine. If so, would you please show me on which pipe to make a T connection on my car? Thanks
My small block chevy shows normal on the gage. But the needle is jerking back and forth a tiny tiny bit. It's a brand new crate engine. Is something wrong?
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
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
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.
its the best, to the point video on subject....covers each and every defect that a vacuum guage can detect....yes, it doesn't discuss why part but at the same time, gives you clear lines hiw to interpret the guage readings....❤❤❤
Ok so, I have a vacuum vibrating rapidly between 18 - 15 in/Hg, at idle. After me doing a wet compression test, I just happened to start the engine with the vac. gauge hooked on and to my surprise, the vacuum reading was stable, just for around 5 seconds at idle, then it went back to the vibrating reading. So now I think my vibrating vacuum is caused by a worn piston ring, what do you guys think? Btw for the dry/wet compression test result, and my cylinder 3 is around 30psi lower compression than the rest at dry and all normal at wet test. Its just that after a lot of searching online, I still have not seen anywhere that worn piston rings can cause the vibrating vacuum symptom.
I have a car that's got a new engine rebuild a year ago and at idle the needle on the boost/vaccun gauge flutters very slighty. Is this normal? sr20det engine
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).
In my engine at idle have a 20 inhg but at 2500 RPM is 26 inhg and shake all car, what's wrong ? Without air filter nothing change, i check timing and Valve and looks good. TPS ?
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.
if you look at the needle when you blip the throttle it actually goes past zero and 2psi positive. I know this is normal but i'm wondering why that happens?
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.
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
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!
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?
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.
Can you hook the vac gauge right on the side of the intake??,, My 2.0 Pinto reading is low, that's the place I see to hook the rubber hose into.
That's a car you rarely see anymore
Impressive video explanation
great video.
I have a 1970 Boss 429 and at 800 RPM idle the vacuum is steady 3 inch and at about 3000 RPM it has a steady 17 inch. I have a high performance Comp cam in the engine. Engine run great and doesn't have 100 miles sense rebuild. Is this normal?
Great video, thanks for sharing. I did the test and the neddle stays about 21, vibrating a little bit, what does this mean?
Sounds pretty normal and healthy to me!
awesome video, thanks
thank you for the this.
I have a reading obove normal where should i start? So i have a restricted intake
Could you not just connect the gauge to the cylinder head? or do you have to attach it to something like you showed
You need to attach it to something with direct engine vacuum, anything off the cylinder head probably wont be direct engine vacuum. Anything off the intake manifold is a good place to connect to. I like to hook it up to the brake booster line.
Oh I see what you mean now, bits of the video confused me. Cheers :)
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.
Where does that vacuum line come from
Wow dude, did anyone tell you that you sound like Garth from "Waynes world"......Excellent 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?
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!!!
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
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.
This one only goes to 10psi!!?? But mine has supposed to be around 50psi..
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
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.
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🙏
Nice video mate, really helpful!
woah
How does this work on a Tesla? I can't find a vacuum port.
Haha
Hello do you have the link to where I can buy the cage? Or any recommend for good cauge?
I have a Hiace with 2trfe. 2012 model. Im using torque pro and it shows my Vacuum constantly at a steady 25 at idle.
Everything seems to be healthy?
Let's see if I can get a response okay I have a Chevy Cruze and the p0011 code has to do with my intake cam problem which the diagnostic said it was the actuator I have changed both intake and exhaust did not fix the problem check engine light still on when I do the vacuum test my engine seems to rev Indy healthy area about 19 2 20 inches of mercury while in idle the needle has a fast vibration and it moves up and down from 18 inches of mercury 2 about 20 and a half inches of mercury so it stays steady in the green healthy area but it is moving back and forward a little bit I'm trying to figure out is something here the cause of my check engine light remain on because the diagnostic mentioned something about timing being off a little I can't really tell everything with the timing chain that I can see lines up to top dead center could this be anything dealing with some valves or Springs
Thank you for making this video. It was very informative and easy to understand ☆
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.
On a fully warmed engine and when I blip the throttle,. my needle drops to zero but then goes straight to 20 and stays steady. It doesn't go to 25 and then slowly settles back down. Do I have an issue?
When your doing these readings. Is it good to turn all Accessories off?
Soon as my compressor comes on my readings drop alot? Which seems normal. Am I wrong?
Thanks for the great video! I have a 351M in a 78' F250, that starts to have white smoke after warming up, but not on first starting. After watching your video I bought a gauge and the reading on start up is a vibration between 15-16 and then after warming up, it fluctuates between 6-20. Do you think I have a head gasket leak?
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...
Everything is new in my 68 Mustang, with a crate stock 302, runs well no issues. But the vacuum gauge shows 15. I managed to get 17 after advancing the ign. timing a little. What do you think? Should I advance it further to achieve 18 or more?
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!
Heres a scenario, my engine is at normal in the green area.....but when I rev it really quick to about 3000 rpms the gauge goes up to 25 hg's when i let go of the accelerater, the gauge slowly drops back to normal green area...but it takes at least a minute or 2 in order for it to get there.
Sounds like its starving for air when you open the throttle it allows air in wich is why I drops to zero. If it's pulling higher vaccum at higher rpm would be due to lack of air in the intake.
Hi my trucks been sitting for a year untouched ,diesel Hilux
Rebuilt engine ,brake boosters not working but I have a new vacuum pump and it registers at 25-6 very steady inches of mercury (300m above sea level )
I do remember the first day I installed the engine I had brakes only ran it for a couple of minutes next morning nothing ,pedal doesn't move at all when turned on ,is it possible the diaphragm weakened over that time
i have a 1600 british pinto engine am getting a vibrating reading between 13 to 15 which i believe is advanced timing ?? the car runs rich mixture but runs really smooth ( it was set up on a dyno test
and it was the only way it would run smooth ( car is now 41years old ) can anyone tell me me can i fit a 7" dual booster -- what i have now is a 8" single and it works fine but the master cylinder has
a problem and the parts are non existent so can i fit the 7" with an upgraded master cylinder of 15/16" original is 3/4" but running on single pot calipers but now have 4 pot calipers each side can any of you guys help me solve this problem
I’m just curious, why wouldn’t the tube be inserted into the manifold instead of the tube?
If you have doubts about where to plug it in, plug it into the line which is sucking air. That's the vacuum source you are going to read.
@@wymple09
Thanks Warren,
I did that, needle is in the green range, thanks very much.
Very good! Such a simple tool yet often overlooked and one of the most useful in the arsenal!
steady vibration 1/2 inch between 21 and 21.5...worn valve guide? Its only 1/2 " but the head is very old, new valve seals new head gasket, all valves adjusted.
I have 89 gmc 5.7 vacuum fluxuation after warm up between 17 and 18 it randomly hick ups and act like a mis engine new I believe it's intake thoughts
US General is chinese? it has"late ing timing" writen on it! (late ignition timing)
4:51 ...okay wait, so the declining gauge pressure is a sign of both an exhaust obstruction AND an air leak in the in the intake manifold? also, if you disconnected one of the vacuum hoses, what is plugging up the port that you disconnected it 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
I've herd people using vacuum gauges to correct idle mixture but I can screw my idle mixture screws in all the way until the engine dies and it doesn't effect the vacuum gauge
What about catalytic converter isn't it a built in exhaust restriction? Should a car with cats drop to -5 during acceleration while not being faulty
Great video! I bought one of these gauges over 20 years ago but never really used it. Amazing what stories these gauges can tell.
My gauge very slowly climbs to 20 but takes about minute to get up there, and if I rev then engine, nothing happens to the gauge ?
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.
Exactly what I needed to see before heading back out tomorrow. Thanks
hello. i did a vacuum reading and the needle is vibrating in the normal range. my engine is 289 what would that mean?
Do I gather that you are talking about petrol engine ? Unfortunately, I am interested in diesel engines.
Not quite clear where exactly to connect it.. Yes, to a vacuum line, but could you illustrate in more detail
So If Accelerate number showing Between 20 to 25 is that normal?
What about when u driving ..at certain rpm and load needle starts to vibrate about 2or 3 in hg
Hi i did the test on my car en i noticed that with the ac on it stopped at 40 but with out the ac on was on green is that normal ? Txjx
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
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.
How does this work if you remove the fuel line from the motor? How does the motor run with this on the end of the fuel line?
Hi my friend. Is this tool suitable for turbo diesel engine cars? I have a Passat B5 1.9 TDI AFN engine. If so, would you please show me on which pipe to make a T connection on my car? Thanks
hey my friend that is a great video I've learned a lot thank you very much
Excellent Vid! I got exactly the info I was looking for. THANKS!
My small block chevy shows normal on the gage. But the needle is jerking back and forth a tiny tiny bit. It's a brand new crate engine. Is something wrong?
If the engine is brand new, I wouldn't worry about it too much.
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
welp... heres to another purchase for me XD and some learning
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
this guy dose not have read for the booklet cause he dont know what he doing
Great job. I really like how you explain how to read the vacuum gauge for different kind of engine problems. Thanks
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 !
Can i use map sensor readings instead of Vacuum Gauge?
yes, its work on toyota hiace too. I change vaccum pump on 200k km(8 years of use)
its the best, to the point video on subject....covers each and every defect that a vacuum guage can detect....yes, it doesn't discuss why part but at the same time, gives you clear lines hiw to interpret the guage readings....❤❤❤
awesome video....very informative ...thanks
Sir this vacuum Guage is used for efi car also or not
Ok so, I have a vacuum vibrating rapidly between 18 - 15 in/Hg, at idle. After me doing a wet compression test, I just happened to start the engine with the vac. gauge hooked on and to my surprise, the vacuum reading was stable, just for around 5 seconds at idle, then it went back to the vibrating reading. So now I think my vibrating vacuum is caused by a worn piston ring, what do you guys think? Btw for the dry/wet compression test result, and my cylinder 3 is around 30psi lower compression than the rest at dry and all normal at wet test. Its just that after a lot of searching online, I still have not seen anywhere that worn piston rings can cause the vibrating vacuum symptom.
I have a car that's got a new engine rebuild a year ago and at idle the needle on the boost/vaccun gauge flutters very slighty. Is this normal? sr20det engine
@Budget Boost DIY Ok Thanks for the help!
This was very good, thank you. Its amazing the amount of troubleshooting that can be done easily with proper knowledge of this tool.
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).
Amazing what you can tell about an engine from an analog gauge.
Looks like my valve guides are no good
In my engine at idle have a 20 inhg but at 2500 RPM is 26 inhg and shake all car, what's wrong ? Without air filter nothing change, i check timing and Valve and looks good. TPS ?
Is that a Replaitz vacuum gauge brand? Made in china
hmm im at 18 /20 on the vac gauge and my heater toggle to the def quit only getting 19.6 mpg
What if you're not in the green and you are in the zone
Best fucking instructional on using a meter
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.
Back pressure says opposite on o2 sensor whole
Hi, I live in Quito, 2.850 m over the sea. Please, can you tell me how much I can expect read at the vacuum gauge in my 383 stroker motor ?
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! thumbs up for sure on a great video. Keep up the great work.
When you blip the throttle it doesn't go above past 17° where it normally stays?
Any suggestions 🤔
if you look at the needle when you blip the throttle it actually goes past zero and 2psi positive. I know this is normal but i'm wondering why that happens?
Dear sir.ive just found this video.absolutety superb.very clear.
This has helped me loads.stevevfrom the uk.