PNogC2S

OK, I've read all the oil leak threads and none seem to be exactly the same as this...or maybe I'm just not connecting the dots.
I replaced the upper and lower valve cover gaskets (even used some Curil-T recommended by Darin to make sure I had a good seal) The valve covers are all dry - none even weeping.
I replaced the grommets on the cam covers b/c they were weeping, but they are not in the right place to be causing this leak anyway.
The leak comes down both sides of the engine, flows toward the back (from air blowing as I drive) and then drips off the last exhaust flange and onto the heat exchangers. So I figure it's coming from something on top, in (or near) the middle of the engine then flowing down both sides. (see pictures)
It's not as bad as it looks (in terms of volume), I've just been letting it go for a while trying to figure out the source.
I previously cleaned everything up and nothing below the engine tins appears to be the culprit .
I cannot see any obvious oily areas up on top of the engine...I've removed the air cleaner assembly and the heater blower and looked on top as best I can... I think I'm seeing the sending unit and it doesn't appear to be leaking.
The big question - Is there anything on the top of the engine near the transmission that could be leaking oil?

993inNC

Looks like you are leaking where the cylinder jug meets the block. Its not a typical head gasket type of union and do leak with age. I have one or two doing it too.

PNogC2S

So based on that diagnosis, this would be a "just live with it" type of situation?
I'd assume there's no way to fix such a leak w/o removing the cylinders from the block, correct?

993inNC

Having not repaired mine, I would believe that to be correct. I tried to tighten a few bolts back some time ago to no avail. I would say just keep an eye on it.

PNogC2S

What bolts did you try tightening?

993inNC

I knew you'd ask me that Its been so long ago, but I believe there are some 10mm bolts that are accessible from underneath and I tried those. Mine that leaks is the drivers side rear most cylinder, I gave a small crank on the bolt just to try something......that was all. After years of tracking the car though, its never really gotten any worse so.....

johnsjmc

The 2 most likely sources for oil from above are the pressure sender and the crankcase vent. You say the sender is OK . Clean the engine and then see if you can check the vent casting.I believe it is still right at the middle rear ,closer to the centre than the sender.This has been a common leak point for decades. I haven,t actually looked at my 993 engine but assume it is still there. You will need to have the intake partly removed so I would have the new gasket and a new sender on hand if I was going to the trouble.

PNogC2S

I went out to look for the crankcase vent, but I don't see it. I see something on the PET that looks like a crankcase vent (it's labeled simply "cover" on the PET) and is in the right area to be causing the problem, but when I look at that area on my car I see the Cruise Control unit - is the cc vent behind that unit?
I'd like to be certain I know what I'm going after before removing the intake.
Thanks!

johnsjmc

I just looked at PET and the vent cover is still there. It is an oval about 3 1/2 x 2 at the rear top right on the center case seam. The part # starts with 901 so it has been the same since the '60s

PNogC2S

Thanks! I'll check it out.

PNogC2S

So it's part # 901 107 073 02, right? The one labeled just "cover".

Is it the part itself that typically fails or is it just a gasket replacement?

FD Motorsports

gasket... but it is a a bit of a job to get to.

PNogC2S

What other "while you are in there" items would you recommend besides this and the oil pressure sending unit 'O' ring?

johnsjmc

Maybe the SAI check valve ? I,ve only heard about SAI problems ,never looked at what is involved but if the check valve is a routine wear item it,s near by on the right I believe more or less under the air filter housing. Also clamp the oil vent hose to the vent cover if it,s not already done.

PNogC2S

Thanks, been down the SAI path already, so that valve is less than two years old. I'll check out the clamp on the hose though.