flywheel seal oil leak?

rhk109 · 02-05-2004, 09:32 PM

Is there a definite way to tell if my oil leak is from the flywheel seal?

Will oil only drip out of the gap between the engine and tranny or can it get sprayed all over the back of the engine? I can't tell if oil is dripping out of the gap or just running down the engine and dripping off near the gap. The rest of the area around the oil cooler is also oily. The oil leak is a steady drip right after I shut the engine off and then slows down to an occasional drip within an hour or so.

I am planning on dropping the engine and replacing the oil cooler, thermostat and breather seals in an effort to stop the leak. I am nervous to remove the flywheel and replace the flywheel seal too. I have found numerous threads about stripping the flywheel bolts.

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rhk109
76 911 3.0

ischmitz · ischmitz's Garage

Get the proper 12 point socket for the flywheel bolts and clean them out with a pointed tool first. Then it's a piece of cake. Using a standard allen socket is a sure recipe for stripping them.

It's hard to tell where the leak comes from. A bad oil thermostat or crankcase breater gasket could be the issue. Once you dropped the engine and have the tranny off it becomes obvious.

Ingo

rhk109 · 02-06-2004, 05:10 AM

Do I need the $30 12 point tool from Pelican or are they available at Sears or the local auto parts store. Is the one from Pelican a higher quality than I will find at a local store?

rhk109

GB83SC · 02-06-2004, 05:12 AM

As posted above, use the right tool for the job.
CAR OFF!! check the hole between the motor and trany,if you find your finger wet, its the seal. Its a straight forward job and dont worry about the flywheel bolts, with the right tool they don't strip out.
Don't forget to change the oil pressure switch while the motor is out.
Also check the intake runner hoses if puffy change them.
Good luck.

GB83SC · 02-06-2004, 05:14 AM

Valuable information on this site -- If we don't spend the money at Pelican you might not get all this information for FREE!

Good luck,

Superman · 02-06-2004, 06:21 AM

According to the Porsche mechanic I trust the most (most of you know who I'm talking about), rear main seals (so called flywheel seals) almost never leak. Nine times out of ten, when a clutch disk and the inside of a bellhousing gets wet, it is tranny oil that has snuck past the input seal and crawled up the tranny input shaft. That's counterintuitive to many people so I expect some static on this one, but my mechanic has decades of experience with ONLY 911s and I believe what he said.

In your situation, rhk, I have a very strong feeling that your leaks are external. I think you have a leaking thermostat o-ring. If the back of your oil cooler, back in the area of the starter, is wet and grimy, then I'd be convinced that the vast majority of leaking oil is coming from that o-ring. If so, a drip of oil will always be present at the bottom of the tranny, right where it would leak out if it were in the bellhousing. don't be fooled. Your bellhousing is probably as dry as a bone. Unless that drip of oil smells like "ninety-weight." Other culprits include oil breathers and hoses, and oil pressure switch.

rhk109 · 02-06-2004, 07:46 AM

It is not gear oil.

I have Webers so I can access the thermostat and pressure swtich easily with the engine in the car. The top rear of the engine in this area is pretty clean. If it was the themostat or pressure switch I would expect this area to be a mess. Am I correct?

rhk109

Rot 911 · 02-06-2004, 08:09 AM

Quote:

Originally posted by rhk109
Do I need the $30 12 point tool from Pelican or are they available at Sears or the local auto parts store. Is the one from Pelican a higher quality than I will find at a local store?

rhk109

While I am a huge advocate of buying parts from Pelican, and I have spent thousands with Pelican, you don't need to waste money. As I and many others on this board have stated in the past the 12 point bit that Sears, Autozone, etc. sells, works just fine. Hell I chuck my Sears 12 point bit right into the impact wrench!

Superman · 02-06-2004, 08:26 AM

Not correct. If the thermostat o-ring is leaking, that is located under the plastic shroud so the leaking oil will not get on top of the shroud. It will get into the case and onto the top of the oil cooler, and mostly dribble down the back of the cooler. Put your head under the passenger side of the car, just in front of the rear wheel. When you can see the starter, you can also see the back of the oil cooler. If it is wet and grimy there, I'll offer ten-to-one odds that your O-ring is responsible for 90% of your oil loss.