Man, I just can't find the source of this oil leak. It's coming down the left (driver's side) corner of the block, trailing down the plastic inspection cover of the auto trans. The firewall is also wet, just left of the distributor. This is an 88 GTA with 5.7L engine. After driving the car, there is a slow, steady drip from under the car. Washing down everything & running at idle on jack stands revealed nothing. We've replaced the oil pressure switch & all of the fittings except the trapazoid block fitting at the rear of the intake manifold. The valve cover gaskets were recently changed & there was no problem after they were changed. A few years ago we R&R'd the intake manifold and I used some killer RTV in place of the end seals. We've had problems with the oil cooler to block o-ring in the past and have a new o-ring on order. Only problem is I have a hard time seeing how oil can get on the firewall from that o-ring. One thought I had, maybe you guys can help with. The distributor o-ring. On my other son's V6 Camaro, I know the o-ring is critical & can produce an active leak, but on this 5.7L, the base of the distributor is not wet. I really think it is coming from the oil pressure switch and/or fittings, but everything was changed but the block fitting. That goofy fitting looks like a male nipple screwed into the block & a female 90 degree trapezoid fitting screwed onto that. The problem with that fitting is if I get it out, I don't think I can screw it back in without removing the distributor or the intake manifold. Any insight here?? The final thought is I'm building too much crankcase pressure because the car is supercharged and I am pushing oil past the intake manifold RTV end seal or past the valve covers gaskets. It is just so congested at the back of the engine, I really can't tell anyting for sure. Any help or suggestions out there?
Thanks, FJK

 

FJK,

You've already covered most of the likely suspects. Your hypothesis about crankcase pressure sould be valid, and may be causing a light oil spray from some rather unlikely sources, like the PCV grommet, oil filler/breather, etc.

If the distributor base is clean and dry, I wouldn't suspect that. The oil pressure transducer is a possibility, as is the dowel/plug for the oil gallery at the top/rear of the left cylinder deck. That plugs the cross-drilled passage to the oil pressure sensor, and will be just as difficult to access/observe with all the congestion back there. Suggesting a mirror is probably moot at this point.

 

Vader: Thanks for being a sounding board on this subject. After reading your reply, it triggered a thought that it is probably NOT the rear RTV seal on the intake manifold. Reason being, excessive crankcase pressure always surfaces at the most marginal sealing point, which would be the sloppy fit of the PCV valve gromet. Besides, I think I located the source. The fitting arrangement for the oil pressure switch on the back of the block. Using compressed air to clean & a mirror, it looks like it is the block fitting. The trick is, at idle it won't leak, because of lower oil pressure. Blip the engine speed & you see a slug of oil spurt out. Still have the question of being able to remove & install this fitting due to accessability problems. Any thoughts or tips? Also, this is that strange trapezoidal fitting. Is this fitting 1 piece or 2 pieces? To me, it looks like the trapezoid head unscrews from the nipple that screws into the block. Can anyone clarify?
Thanks, FJK