RSAErick

Thanks JC,
Hopefully tomorrow if I can put my car together, I'll report on whether the new pressure valve is still releasing oil. If it is, I'll fear that new rings are in order. ;(

RSAErick

Well, it appears that my pressure release valve is NOT the culprit. I put everything back together, put oil in it, warmed it up, topped off the oil, and took it out for a spin. There is STILL oil spewing from the check valve.

Possibly related: I now have low oil pressure at hot idle -1.5 - 2 bar @ 800 RPM @ 9 o'clock hot - enough to trigger the oil pressure warning light. The oil level is correct by both gauge and dipstick.

I'm out of ideas. If anyone has any more suggestions before I take it to a mechanic for repairs, I'm all ears.

Thanks,

JasonAndreas

I wonder if the low pressure warning coincides with the valve opening on top of the oil tank?

JC in NY

Another possibility: Your oil pump is shot. At least the pressure side - but the scavange side is OK. Thus, all of the oil gets pumped into the tank and overfills it. The pressure side being shot cannot put out enough pressure.

jimq

Isnt that pretty much normal pressure hot? My cars allways sat around there at hot idle.

Red rooster

As far as I know the check valve in the top of the tank is there to allow an escape route for excessive crankcase fumes.My 89 C4 tank doesnt have this valve , so a later improvement.The crank case fumes are fed into the top of tank by the large hose starting from the rear center of the motor.There is also a small hose from the inlet manifold to suck some of the fumes into the manifold when the engine is on light throttle/overrun.This is the normal closed crankcase venilation system applied to a dry sump motor.
With the symptoms you have it sounds like either the motor is breathing very heavy (rings ) or there is too much oil in the tank.To check both ,fill the motor so the level gauge is down on the red with the oil hot .Using your hand as a temperature probe !! gently touch the tank and confirm that it is MUCH hotter below the level sender than above.Try your leak tests with this lower oil level.
If you want to check the crankcase fume level ,part the large hose at the joiner in the top RH corner motor bay and see what amount of fumes you get.The idle speed /running should be upset by doing this if the inlet manifold hose is OK.
I think that you are probably running a too high oil level for track use.
Lets see how it goes.
Geoff

RSAErick

My mechanic (Monty at Redmond European) tested the oil pressure at high load/RPM. Apparently the oil system pressure exceeded the release pressure spec for the valve.

He checked the compression and found one of my cylinders to be reading 20-25% of normal compression. As JC and others suggested, it appears that the cause of the oil system overpressure may be rings. The engine will need to be opened to confirm this, but I'm preparing for the worst.

I started a new thread HERE .

Thanks for everyone's contribution in finding this problem.

MarkRobinson

On my 965, the main oil line in the rear fender (from the engine) is braided steel over rubber: the braided steel part had freyed where it rubbed the upper tank support (1st page, picture you posted).

I had to loosen the line, re-run it outside the mount to verify that oil was seeping from behind the freyed (slightly freyed) stainless braiding.

Normal rocking/slight movement from (my hypothesis) low pressure to higher oil pressure caused this to eventually start leaking at about 100k miles (1991 car). Just a thought. Had a local hydraulic place rebuild the line...$100 bucks.