Crankcase pressure and leak down test results:
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Joined: Mar 2002
Posts: 2,743
From: Baton Rouge, LA, USA
Re: Crankcase pressure and leak down test results:
Now that I've determined that the bottom end is Ok, my plan is this:
- Replace the factory PCV with a Advance Auto PCV. It seems to seal off better with reverse pressure.
- Build a baffled catch can to mount to the valve cover. This will catch oil rather than letting it go out the vent hose, then drain the oil back into the valve cover when out of boost.
- Run the vent hose back to the inlet of the compressor to help draw vapors (pressure) out of the crank case.
Mike
- Replace the factory PCV with a Advance Auto PCV. It seems to seal off better with reverse pressure.
- Build a baffled catch can to mount to the valve cover. This will catch oil rather than letting it go out the vent hose, then drain the oil back into the valve cover when out of boost.
- Run the vent hose back to the inlet of the compressor to help draw vapors (pressure) out of the crank case.
Mike
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Joined: May 2003
Posts: 6,661
From: LA (lower Alabama)
Re: Crankcase pressure and leak down test results:
Originally Posted by Stephen 87 IROC
PCV valves and race cars don't mix. I don't want to be sucking oil and water vapors out of the crankcase and feed it back into the intake. It doesn't burn too well.
That still doesn't explain why you blew the dipstick out unless the boost pressure prevented the PCV from sucking out the crankcase pressure until it just built up too high.
Take out the PCV and add a second filter. Having a filter breather in both valve covers will just vent out excess crankcase pressure. If lots of oil gets past the breathers and covers the rocker covers then you may need some sort of evac system.
That still doesn't explain why you blew the dipstick out unless the boost pressure prevented the PCV from sucking out the crankcase pressure until it just built up too high.
Take out the PCV and add a second filter. Having a filter breather in both valve covers will just vent out excess crankcase pressure. If lots of oil gets past the breathers and covers the rocker covers then you may need some sort of evac system.
The reason for the dipstick blowing out is it's putting boost in the pan,the reason I said in an earlier post to install a positive one way check.
Registered User
Joined: Oct 2002
Posts: 1,639
From: Toledo, OH
Re: Crankcase pressure and leak down test results:
Is drawing crankcase vapors back through the compressor a normal thing on turbo cars?
Doesnt sound to me like it would be worth all the effort when you could just buy one or two valve cover breathers and be done with it all together, unless of course you need an evacuation system.
Doesnt sound to me like it would be worth all the effort when you could just buy one or two valve cover breathers and be done with it all together, unless of course you need an evacuation system.
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Joined: Mar 2000
Posts: 2,037
From: 51°N 114°W, 3500' elevation
Re: Crankcase pressure and leak down test results:
Running it back to the compressor would probably help but it would have to go through a puke tank first. I saw a fabricated tank like what you need on a car that was using a belt driven vacuum pump.
Hose comes off the valve cover to the bottom side of the puke take. Tank is filled with fuel cell foam to provide baffling. A drain is at the bottom when needed. A hose comes off the top side and goes to the inlet of the vacuum pump/compressor. That way the compressor gets clean(er) air than what it would normally pull out of the crankcase. The puke tank will need to be sealed tight. The tank I saw as about 3" square and about 12" long all fabricated out of aluminum with a bolt on top so the foam could be replaced from time to time.
Hose comes off the valve cover to the bottom side of the puke take. Tank is filled with fuel cell foam to provide baffling. A drain is at the bottom when needed. A hose comes off the top side and goes to the inlet of the vacuum pump/compressor. That way the compressor gets clean(er) air than what it would normally pull out of the crankcase. The puke tank will need to be sealed tight. The tank I saw as about 3" square and about 12" long all fabricated out of aluminum with a bolt on top so the foam could be replaced from time to time.
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Joined: Dec 1999
Posts: 9
From: W. Monroe, LA
Re: Crankcase pressure and leak down test results:
Mike,
Any luck so far? Did you try the GN PCV PN that I emailed to you? Check out this PCV catch can:
http://www.accmachtech.com/pcvcatchcans.htm
Any luck so far? Did you try the GN PCV PN that I emailed to you? Check out this PCV catch can:
http://www.accmachtech.com/pcvcatchcans.htm
Thread Starter
Registered User
Joined: Mar 2002
Posts: 2,743
From: Baton Rouge, LA, USA
Re: Crankcase pressure and leak down test results:
If I continue to have problems, I'll try the GN PCV or just a check valve. I don't even have the headers and turbo back on it yet.
Mike
Mike
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