Pesky oil leak

[Dano"T"]

I have a recently majored C-85-8 on my BC-12D and before the overhaul I had an oil leak at the accessory plate on the front of the engine. We thought we had the problem solved after the overhaul. It's not as bad...but it is still there. We put a new gasket on (again) and it is fine when I run it up....no leak. But after I fly it it has a small leak near one of the studs. It's almost as if the oil is pushing right up through the threads. I'm confused. Any advice? P.S. The accessory plate appears to be homemade, but it is flat and true and we gooped up the gasket too.

Dano
N44008

[Richard Boyer]

Re: Pesky oil leak

Just asking......

did you use silk thread....
what did you use for the goo between the case halves? I'm one road so I can't look at my manual, but I think we used locktite 515. Continental calls it "grape jelly" and it has an actual part number.


Richard Boyer
N95791
Georgetown, TX

[jgerard]

Re: Pesky oil leak

I like to use the NAPA aviation permetex and silk thread. Is it possible the case is cracked? I have seen 3 "C" series continetals crack just infront of the # 4 cyl. Almost impossible to see, and the oil just magicaly appears....

Jason
N43643

[Dano"T"]

Re: Pesky oil leak

We used Napa aviation permatex, and the case was inspected very carefully when we had her apart. It almost appears as though the oil creeps right up the threads on the stud. If I remove the stud and inspect the inner threads and case within maybe I'll find some clues. I sure hope to heck there isn't a crack in the case along the threads.

Dan Gervae
44008

[Richard Boyer]

Re: Pesky oil leak

Mine had the same problem. Oil coming out of the case, especially at the thru bolts. It wasn't something as drastic as a crack though. We made sure that each bolt had a little loop of thread going around it with the ends of the thread overlapping and another around the whole case. It is real easy for those to move when putting the halves together.

When we split the case for the original leak, everything looked fine. All the threads were exactly where they should be. But it leaked worse than a pack of dogs at a fire hydrant convention!

Richard Boyer
N95791
Georgetown, TX

[Dano"T"]

Re: Pesky oil leak

Thanks for that info. Mine leaks very little, but I want to nip it in the bud. Sounds like that may well be what is going on with mine. I sure didn't see any cracks in the case. We'll try the thread and see what happens. What really confused me is that no matter how long I ran her up...it would'nt leak. When I landed there would be oil dripping on the cowling.


Dan Gervae
N44008