Suspected Transmission oil leak..

[Dave Phipps]

In the last few years I've found myself having to add about 3 or 4 quarts of oil on two occassions to one of my M-20 gears. No obvious oil leaks..and I think I properly filled the oil (as measured on the dipstick with the engine at idle) after each oil and filter change. So my question is...where could the oil be going?...

The most obvious possibility to me would be that a pinhole leak might exist in the transmission oil cooler, allowing oil to pass into the cooling water outflow..but I'm not seeing any unusaul oil residue in the exhaust water discharge..

Any other thoughts or suggestions for me?.......Thanks.....

[Genesis]

USUALLY you do not leak gear oil into the engine from the rear main seal - its normally the other way around (engine oil into the gear) - but its POSSIBLE for it to go that way.

That's the problem you don't want, as the labor to R&R the gear to get to the seal is not cheap! The seal itself is cheap....

I'd expect the problem is in the gear cooler if you can't find the oil leaking anywhere into the boat - take the cooler off and have it pressure tested (put 100psi of air on the oil side and submerge - if it bubbles you know what that means!)

[Dave Phipps]

Thanks Karl. That's about all I can do at this point...