HOW DO YOU TEST AN ENGINE VACUUM? | Step by Step 

100%, its the most powerful yet underutilized tool! I have used a vacuum gauge to find many of those hard to find issues. Plus if you can't use a vacuum gauge then how can you use a delta sensor with a scope to monitor vacuum? I agree vacuum gauges need more use guys!

@@MasterAutomotiveTraining The issue with vacuum gauges is that you cannot reliably diagnose Atkinson cycle engines as they do not have much of any steady intake vacuum (as they actually push air out from the cylinder in part of the compression stroke, which nullifies manifold vacuum). If you use a vacuum gauge on an Atkinson cycle engine, then it will read near zero at all times. This is the reason why Toyota uses separate vacuum pumps to supply vacuum for most of their engines in the last 10-15 years. It is also why they don't have any testing procedure that involves testing for vacuum for nearly anything engine related. So right off the bat that one of the US' largest car manufacturers where you can't use vacuum gauges for diagnosis. They're great, but they have some severe limitations.

That, and using a smoke machine to find leaks (Exhaust, intake, etc)

​@@LordOfSilense Would it be good to use on Saturn engines? I have a Saturn Ion-2 2.2 and think i might have a vacuum leak

That's so true! I can't find the issue with my 289cui and now iam hoping to get it diagnosed with the vacuum gauge!

At wide open snap throttle the butterfly valve at the throttle body is completely opened up to atmospheric air …. therefore, no difference in pressure exists - in other words; no vacuum can be created .

Yes, since low compression creates less vacuum, will create less negative pressure on the front of your brake booster leading to lessened brake effect. Do you feel any braking problem?

My brake caliper cylinder stuck even new caliper. I change brake vaccum hose but still caliper cylinder stuck & brake Rotor get hot. Is any body know what will be problem.

Great suggestion! Coming soon!

Thank you

Glad it was helpful! 😁

Thank you! Thank you for your support!

You are so welcome! Glad it helped.

Thank you for those kind words!

You are most welcome

Thank you!

It's a good idea. However the codes might have been cleared by the seller just before you scanned it, so your Check Engine Light will be off. And then the light may come on on your way home.

45cm hg is equal to 17 hg” no need to rev it, you are within proper spec.

Slightly on an RC you’ll see if one or more cylinders are low on compression. While a cranking vacuum would be more for all cylinder like a chain or timing belt out.

I read your question, does the Lucerne also have a drivability concern? Mil? DTCs?

That's a great question Bob. If your car has a MAP sensor the reading you see is the difference in pressure from atmospheric to intake. Minus the reading your MAP sensor gives to the BARO reading on your cell phones weather app, the difference is the engine vacuum. Example: MAP reads 17hg and your BARO says 29.9hg. Your engine vacuum would be 12.9hg" did that make sense?

@@MasterAutomotiveTraining ok thx!

@@MasterAutomotiveTraining i do have a VAC gauge next time I'll check both ways an see what i get for readings.

Fuel pump fuse. 😁

drive.google.com/file/d/1cjP8svFw_cq6EmSDaJe_MwbyWIfwr3C1/view?usp=sharing

8:15 ​@@MasterAutomotiveTraining8:15

Hi Bill, what vacuum port are you using?

@@MasterAutomotiveTraining I used two different vacuum lines off the intake manifold. I checked the exhaust back pressure. It indicates a blocked exhaust. I'm wondering if I also have a egr problem. Thanks

Unplugs vacuum hose from intake to EVAP Purge solenoid and plug your vacuum gauge into the intake port.