gregg911

I've been chasing this leak year after year and have tried everything. It's rained here in So Cal a lot this year so I haven't driven my SC much (my wifes convinced it's made out of sugar and I'm afraid it'll melt). I did use a pressure washer and citrus degreaser and removed all grease and oil from the engine compartment and underside about 2 months ago and the car has sat since. I went out to detail and get the car ready for spring and summer and noticed that the leak is BACK!!

I took off the wheel and jacked the car up and got under with lots of lighting. I followed the leak to the seam where the head and cylinder barrel meet. It appears as if there is a small leak the develops here, accumulates and migrates down to the valve cover and then onto the heat exchanger where it smokes when it boils off.

Do you guys think that if I drained the oil, removed the valve cover and torqued the head that the leak would go away??

Best guesses are appreciated.

Thanks in advance,

Gregg

Steve Weiner-Rennsport Systems

Gregg:

Several issues here; SC engines do suffer occasional head stud failures and that can account for the leakage that you see. Needless to say, that requires some engine disassembly to repair.

I would pull the valve covers and very gently test all the head nuts to see if all of them are at spec. Use a well calibrated, accurate torque wrench.

Marty916

I've seen a few porous cylinder castings as well but if this leak just recently started you might try the re-torque.

gregg911

Here's a dumb question, is there an oil jacket that runs from the cylinder to the head? Is there somewhere that I can find a detailed drawing or something similar that details the 911 engine. I've always wanted to see one.

Steve Weiner-Rennsport Systems

Hi Gregg:

There are 4 large tubes that return oil from the heads/cam area back to the crankcase; 2 on each side and you can clearly see them if you look under your engine, just above the heat exchangers.

Got to Barnes & Noble or Borders books and get yourself a copy of the Bentley SC shop manual. Its relatively cheap and will show you a lot about your car and how fix things.

fixnprsh

I agree with steve, try to retorque the heads, I would start with the lower row on the side that is leaking. If those check OK try the uppers.

Dan Cobb

I hear about this "can't-get-to-it-unless-the-engine-is-out" sensor at the front of the motor (against the sound pad) that is a notorious leaker. This probably wouldn't be the case here though as it has been sitting with no oil pressure correct?
I've noticed a bit more of a leak on mine as it has sat for awhile, but I start it otfen enough to suspect this gasket/seal may be my problem.
I've also noticed oil along the case seam, but this could just be the quickest route to the ground.
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Steve Weiner-Rennsport Systems

Hi Dan;

You might be referring to the oil pressure sending unit which sits just above and slightly to the right of the flywheel next to the engine breather cover. These are notorious for leaking oil down over the clutch (thus ruining it) and appearing like one has a leaky RMS.

The case seam gets oily from this, as well.

Its accessible with the engine lowered down somewhat (5"- 6" or so) on the right side and through the right rear wheel well across the right side of the engine. Your Bentley book will show its location.

art

Another place for seemingly unexpainable oil leaks is the rocker shafts. You can put new seals on them(not sure if SCs have them stock), but don't do it unless you are very sure. Once disturbed, they can come loose again if extreme care is not taken.

Dan Cobb

That's it Steve,
I forgot exactly what the sensor was. I'm considering cutting an access hole from behind the rear seat, then making a cover plate and re-installing the seat back.
Is this as bad an idea as I suspect?
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Steve Weiner-Rennsport Systems

Hi Dan:

LOL,..I've never seen the need for such measures,...

I have always made it a habit (for the past 30+ years) to install a new oil pressure sender everytime I did a clutch job to avoid trouble. In your case, its just not that hard to lower the engine enough to change that out without making an access panel that has the propensity to leak oil fumes. Just one man's opinion, tho,.....