AmericanTorque

My 1990 c4 has adopted an oil leak that is hitting my exhaust when I gun it. The smoke is coming from the rear of the engine adjacent to the dipstick, and cylinder six. I have replaced a few parts on it attempting to cure the problem, but no luck.
Parts replaced:
- valve cover gasket
- oil pressure sender unit
- dip stick tube
- valve cover

No smoke is coming out of the exhaust so I think I'm good on the internals. Any in put is appreciated, thanks.

shootnstarz

My 89 had a leak so bad when I got it blue smoke would boil out from under it at stop lights, I believe it was the rear seal or possibly the oil pan gasket.

I installed one (1) quart of Lucas Oil stop leak and the leak stopped and hasn't come back in 7 months, including a 1565 mile trip through the mountains.

Rick

mlm0

Intake manifold leak?

corvetteronw

They are famous for leaking at the front and rear of the "china wall". Pull the intake and replace the gaskets. Dimple the china wall on both the block and intake side and use The Right Stuff instead of the gasket that comes with the set. Here is a pic of the rear of the block with The Right Stuff in place:

AmericanTorque

I installed one (1) quart of Lucas Oil stop leak and the leak stopped and hasn't come back in 7 months, including a 1565 mile trip through the mountains.

Rick[/QUOTE]

Thanks man. Il defiantly look into that, but I really want to find the root cause of the problem too

AmericanTorque

[QUOTE=corvetteronw;1589960203]They are famous for leaking at the front and rear of the "china wall". Pull the intake and replace the gaskets. Dimple the china wall on both the block and intake side and use The Right Stuff instead of the gasket that comes with the set. Here is a pic of the rear of the block with The Right Stuff in place:

I purchased this car a little while back, and the previous owner had the receipts for all the parts he had purchased and gaskets change. He changed the intake manifold about 4000 miles ago. Do you think the gasket could have already turn to ****?

kimmer

I love that stuff.:-)

corvetteronw

[QUOTE=AmericanTorque;1589961666]If he used the gasket set for the China walls then there is a good chance that it did not swell up and seal properly. The Right Stuff really works to seal any gaps.

AmericanTorque

[QUOTE=corvetteronw;1589962723]I'm going to take off the manifold this weekend and give it a try. That's total bull that GM doesn't know how to prodcue a proper gasket. Another thing is that the leak is more on the side of the engine by cylinder 6. thanks for the help corvetteronw

vettespecial

I own a 90 Coup L98 and it has 270k. the car runs great long tube headers, just put on new Bilstien shocks. How ever the car seeped oil
from intake,oil pan and rocker covers. I replaced all those gaskets and
installed new PVC fresh air hose and new PVC and its hose. after about a year and 6ooo miles its all starting seep again and i notice oil up in the PVC fresh air hose going to the throttle body, so i know the rings are allowing oil to blow by, and overpresuring the crankcase
beyond what the seals and RTV can hold. Using Lucas oil additive
or other products has helped a little to ring/cylinder seal, but a new
engine will be my fix in a year or so with better heads and cam.
But for now i wont waste time/money trying to stop a seep.