Positive Crankcase Ventilation (PCV) test......
Thread Starter
Safety Car
Joined: Feb 1999
Posts: 3,504
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From: Mexico Beach FL
Positive Crankcase Ventilation (PCV) test......
After reading this thread: http://forums.corvetteforum.com/zerothread?id=733302
I decided to test my PCV system.
On my '92, the ventilation path is:
1) Air cleaner
2) from throttle body into right valve cover
3) From crankcase under manifold into PCV valve and into the vacuum of the intake manifold.
I decided to check for leaks.
I took the hose off the throttle body and plugged it with a vacuum gauge.
With the engine warmed up at idle, it takes about a full minute for the intake vacuum to pull a vacuum on the volume of the crankcase, valve covers, and oil pan, etc.
My engine, even with a performance cam that reduces my idle vacuum from 20" of vacuum to 15" of vacuum, pulled 3" of vacuum on the engine internals at idle.
I'm wondering what others have gotten doing this procedure so I can compare it.
My guess is my dipstick has a good seal along with the rest of the engine.
I haven't tried it, but I think you could test your dipstick by putting the dipstick into a long hose and pulling a vacuum on it with a hand vacuum pump. My guess is you could draw about 20" of vacuum this way.
Tom Piper
[Modified by Tom Piper, 5:24 PM 1/30/2004]
I decided to test my PCV system.
On my '92, the ventilation path is:
1) Air cleaner
2) from throttle body into right valve cover
3) From crankcase under manifold into PCV valve and into the vacuum of the intake manifold.
I decided to check for leaks.
I took the hose off the throttle body and plugged it with a vacuum gauge.
With the engine warmed up at idle, it takes about a full minute for the intake vacuum to pull a vacuum on the volume of the crankcase, valve covers, and oil pan, etc.
My engine, even with a performance cam that reduces my idle vacuum from 20" of vacuum to 15" of vacuum, pulled 3" of vacuum on the engine internals at idle.
I'm wondering what others have gotten doing this procedure so I can compare it.
My guess is my dipstick has a good seal along with the rest of the engine.
I haven't tried it, but I think you could test your dipstick by putting the dipstick into a long hose and pulling a vacuum on it with a hand vacuum pump. My guess is you could draw about 20" of vacuum this way.
Tom Piper
[Modified by Tom Piper, 5:24 PM 1/30/2004]
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Re: Positive Crankcase Ventilation (PCV) test...... (Tom Piper)
I've been trying to track down an idle air control problem on my vEscort, and thought maybe the PCV system was broken, so I put my finger over the valve cover hole, and within three seconds it launched the oil cap across the building! :eek:
I would suggest changing your PCV valve, they're like $2, and the little ball valve gets sticky after time.
Good luck!
I would suggest changing your PCV valve, they're like $2, and the little ball valve gets sticky after time.
Good luck!
Thread Starter
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Re: Positive Crankcase Ventilation (NoWorries)
I would suggest changing your PCV valve, they're like $2, and the little ball valve gets sticky after time.
Good luck!
Good luck!
So, no parts replacement is necessary.
My question is: what amount of vacuum are others pulling under the same circumstances?
The more seal leaks and blow-by you have the less vacuum you can pull. The higher the vacuum reading the better. But, there are limits to the amount of vacuum that can be pulled -- even with good seals, they will leak some air.
My '92 C4 pulls about 3" of vacuum, and my Lincoln TownCar pulls about 1-1/2" of vacuum.
Tom Piper
