John H

I have a 74 911 with a 2.7. The car started leaking oil on the PO. He took it to a "shop" and they told him he needed a rebuild due to a cracked block. (PO in not what you would consider mechanically inclined so I just don't believe what the shop told him nor do I believe he actually understood what they said the problem was).

The oil is all over the back of the motor and transmission. I pulled the lower valve covers thinking head stud. All 12 of the cylinder head nuts are there and are tight. Nothing looked unusual of fell out of the motor. The oil seems to be coming from what (if this was a 996) I would highly suspect to be the rear main seal area. It's hard to get a good look.

Anyway, are smallish then worsening oil leaks associated with pulled head studs? The car seems to run good but smokes. I do not think it is oil smoke. What I think it is is steam coming from the exhaust. To confuse matters more, when I loosened the rocker covers, what appeared to be water ran out. Not a massive amount but enough that it certainly caught my attention. Also, when I was under the car while it was running, where the exhaust manifold mates to the exhaust pipe (there is an exhaust leak there) water was blowing out. Maybe the water is just condensation thus the "smoke" from the exhaust.

My quetions are, is the oil leak a symptom of a pulled head stud ( I'm paranoid due to a 2.7)? I do not hear any unusual noises while under the hood or the car such as the pop pop pop that I read about in another thread.

Do rear main seals fail on these cars with any type of frequency? The car only has 73K on the clock and has obviously sit alot. Could it be that simple that the rear main dried up and is leaking?

Any other ideas as to what would cause this? I assume if I drop the tranny, it will become clear if the rear main is what is leaking.

TIA for any input.

mo_gearhead

"Steam coming from the exhaust"?? Ok ...burning off some condensation I can understand. but you cannot be getting "steam" in the exhaust from an air-cooled, '74 2.7 engine???

"Water coming out of the rocker cover area" ?? What am I missing here??? I'm confused!!

John H

Me too. I just checked the oil and it was milky. I drained it and watery oil then oil came out. WTF. I think the problem was that somehow water fot into the system and overfilled the oil making the passengerside of the engin look like it was leaking. It was wwwaaayyy over filled. Drained the oil and am now replacing it. How does water get into the oil? I jsut got the car so I have no idea how that could have happened. Anyway, i'll report back after I get the fresh oil in and up to the appropriate level. Weird.

mo_gearhead

Well. it sounds like someone deliberately tampered with the car (introduced water into the oil tank??).... or the car has possibly been in a FLOOD? Do you not know any of its history? Are there any other signs of water damage (unusually rusty rotors, or unplated rusty bolts on underside, in the interior floors or trunk area?) Pull back the carpets and check. This is a scary scenerio.

SeattlePorsche

Are you sure the leak is not coming from above the tranny at the front of the engine? That's where the breather cover gasket, t-stat and oil pressure sender are and they leak.

John H

I think the leak was coming fromthe breather area.. My nose does not work so what I thought was white smoke like steam was really oil. I am wondering if the oil thinned out from gasoline. I know the PO and it was not deliberately messed with or in a flood. I think I just jumped to the wrong conclusion too quickly.

I drove it to the gas station to put some new good gas it in and I left a thick fog behind me. It was actually pretty funny. It smokes like nothing I've ever seen, except for maybe some F1 catastrophic failure. I doesn't knock, ping or seem to be noticeably down on power but somehow, at least one cylinder is being injected with a massive amount of oil.

Since I bought it as a project car, I'll just end up pulling the motor and going through it over the next year or two. No big deal. Thank God it's not my daily driver.

Peter Zimmermann

John: OK, let's clear up the water from the lower valve covers comment. This is completely normal on your vintage car, the area where it came from is simply a condensation trap, and I've seen what you're talking about humdreds of times. The heavy smoke on the way to the gas station probably occurred because of an oil build-up, from being overfilled, in the muffler/exhaust. Sometimes it takes as long as an hour of driving for that condition to clear up. Next, to check your head nuts/studs properly torque them to 15 lb/ft, then 18 lb/ft, then 21 lb/ft, and finally to 23.5 lb/ft. As you sneak up on the spec you will learn if any of the studs are starting to pull. Don't worry, you don't have a cracked block, that just doesn't happen. You might have a leaking thermostat o-ring (tricky to change on your CIS car with engine in, but it can be done), or a leaking crank seal at the flywheel (rear main is not a term commonly used when discussing 911s), which requires engine removal. A last note, before topping up the engine oil level to approximately halfway between "max" and "min" be sure that the engine is at full operating temp, the car is sitting on level ground, and idling. Have fun with it!
Pete

John H

Peter

Thank you for your input. I think you probably nailed it on the head with the overfill and exhaust full of oil. It seems to be clearing as I let it idle in the driveway. It is way to embarassing to drive around. It appears to be dropping off significantly. I think my buddy was a little to nervous about running low on oil and kept adding til he overfilled. He probably added more when it started smoking. I am going to let it idle abit over the next few days and maybe run it around the block after dark to see if it clears. I try to get that issue addressed and then clean the motor and look for the leak. I am thinking it may have been "leaking" from the breather due to the overfill.
Again, thank you for your expert advice and spending the time to post it here.