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Thread: crankcase pressure ?
09-17-2004 05:38 PM #1
crankcase pressure ?
Kept smelling engine fumes, decided to pursue it. Thought it was from the methanol/h20 injector. disconnected it, still smelly. Thought I might be pressurizing crankcase, so I teed a vacuum/pressure gage at hose from valve cover and ran a hose into cockpit. Getting no vac and 1-2 psi pressure at 9 psi boost. Jumps to 3ish when rapidly letting off throttle.
Should there be a vacuum there when there is a vacuum reading on my boost gage? Is this too much crankcase pressure?
BTW, M30 is old Cartech setup with IC.newer intake and still L-jet
Also has a Turbox blow off valve venting to intake. Could this add to problem?
09-21-2004 07:04 AM #2
Re: crankcase pressure ?
You shouldn't have positive pressure in your crankcase. Check where the PCV hose from your crankcase goes. Mine was going to the throtle body (M42 engine). I had installed a check valve so the engine can suck fumes from the crankcase but couldn't send pressure to it. In theory it was a good idea. But in practice, one day, the check valve didn't do its job and I pressurised the crankcase to 7 psi and the front crank seal leaked at high engine RPM and splashed oil all over the engine bay.
So now, I just routed a hose from the valve cover to under the car. I will eventually install a small filter at the end.
Some people install a catch can to catch condensing fumes.
09-21-2004 07:32 AM #3
PCV hose was
routed to original Cartech IC pipe which goes between AFM and turbo intake, but there was a diaphram valve between that connection and the IC. I think that might have been Cartech blow off valve, but I'm having trouble getting grasp of Cartech parts. Couldn't see down in there very well to look for leaks, etc., so, yesterday I removed the intercooler (had a bunch of oil in it), fabbed and spliced a pipe in there and ran PCV hose directly between AFM and turbo intake. There is still the turbox blowoff valve (which was not ororiginal equipment). I will check crankcase pressure today to see if it is still pressurized. I'd like to keep it hooked up there as other posts suggest vacuum for pcv. I sure wish I could get a schematic on the Korman installed Cartech system. Seems like there is too much oil coming out of pcv hose. Oil now splats out of blow off valve onto top of engine. I don't know if I have excessive oil coming out of pcv, or not. How much is too much? Only had car 3 weeks, trying to track down leaks and prevent destruction
09-21-2004 07:44 AM #4
Re: PCV hose was
Having the PCV before the turbo and intercooler will eventually fill (sort of) your IC with oil residu like you saw in yours.
May be you have a lot of blow by, your rings are may be worn and a lot of compression goes in the crankcase. Did you check your static compression to see if they are within specs?
09-21-2004 08:53 AM #5
Re: PCV hose was
No, not yet. Could hardly even see the plugs with IC in place. Gonna check it today.
Have now checked vac at pcv hose while connected directly between AFM and turbo inlet. No measurable vac at idle, although is pulling some as car dies when disconnected. Should there be a measurable vac there?
Have not checked under boost.
09-21-2004 02:02 PM #6
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