dominick550

My 90 C2 used to be fairly dry, but last year it started leaking from what appeared to be, well, everywhere! Front, back, sides, top, bottom... it looked like all seals gave up the ghost at once. However, upon further investigation it looked like all the leaks were originating up top, on the bottom of the intake then running down all over the place. So I opened up the intake and sure enough, oil was everywhere and was pooling at the bottom of the manifold.

Surprisingly the car doesn't smoke at all, not ever after sitting for long periods. I even had a friend follow behind and watch closely on acceleration and deceleration, nothing.

So what gives, how could all this oil end up so high in the intake? I see two hoses coming from the oil tank that tie into the intake, one for crankcase ventilation I assume, but what's the other small one?

One last clue, if I fill the oil when warm to mid dipstick, it seems to leak much worse. I have to run about 2 quarts low all the time, otherwise I get so much oil leaking that it starts to smoke at stoplights.

creaturecat

you sure you have the correct oil level? looks like a classic case of overfill.

justin-in-athens

I have found that running a little "low" is also best. What does your gauge say? Many people will tell you they like the read the stick, but frankly I prefer the gauge. Anything over dead middle on it, and you will see oil in the intake from my experience. One of those two hoses you mention is basically for oil vapor recirculation, so I think you are always going to find some up there.

I would also take this opportunity (since you have the intake mostly apart) to check the "triangle of death." Leaks form this area can create quite a mess.

dominick550

Pretty confident it's not an overfill issue. I've had a number of 911's over the years and am familiar with that. I actually run it really low, just on the bottom notch on the dipstick when warm at idle. The gauge barely registers at that level, but if I go mid dipstick it really starts to leak.

dlpalumbo

I just had my intake apart and noticed same thing. I thought it might be normal as crankcase does vent through there. I was also chasing topside oil leak. Changed oil pressure and temp gauges and seals. Things have seemed to have dried up.

How many miles on engine? Ring blow by might send more oil through breather.

dominick550

Interesting. Motor has 148K now, but doesn't smoke any. I'm starting to wonder about ring blow by..

prschmn

[I]'d say a leakdown test would be a good starting point. Too much and the tanks going to see pressure which is going to give you that result.