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Oil leak above the oil pan/intake plenum

Veetail88

Well Known Member
I have an oil leak. It originates between the crank case halves just above the oil pan/intake plenum. Will torqueing these bolts a bit more seal this or is it a bigger problem? :confused:

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It probably won?t help but it?s also probably not a problem, I have heard some say there engines don?t leak; personally I have never seen a dry Lycoming with more than a hundred hours. If it?s pouring out then ok maybe a problem, if it just has drips hanging off the bottom and everything underneath has a shine of oil on it that?s normal.
 
My Leakoming has several spots like yours. It doesn't consume extra oil however. I clean it once in a while with cloth using avgas. You will see these oily spots in some weird places on your engine.
 
Unfortunately Lycoming and many others still use 60+ year old techniques (silk string) to seal cases halves and they will leak sometimes in short order. In this case it appears the sump gasket was put on dry (another way to ask for leaks) and because of that there is nothing effectively sealing that corner. You might try removing the sump and replacing the gasket with it rubbed on both sides with Titeseal.

And yes they can be made to not leak, I was just looking over the weekend at an A65 Continental I built several years ago that operates several hundred hours a year and it only had some minor seepage around the cylinder bases.
 
You know, it's funny. I have a few spots like this on my engine,in addition to one at the nut that secures the oil strainer -- you know, the one that basically is torqued to specifications by simply blowing on it. :p

But I'll be darned if I can get that thing to use much oil.
 
Oil Leak

The leak is from the crankcase halves where the silk thread terminates. If you remove the 1/4 inch crankcase bolt, clean the hole and then reinstall and pro-seal the bolt hole, it will likely stop the leak. Do not tighten the crank case bolt or the oil pan bolts excessively. Localized tightening of either of these can result in crankcase or oil pan cracks. I've seen it happen.
 
I'd check the torque on the bolts, but don't torque past book values. Personally I'd just live with it because (say with Australian accent):

"That's not an oil leak... THAT's an oil leak!"
rodthrucase2.jpg


:D
 
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Thanks folks. I guess I can live with a little oil drip here and there.

My 06 Ultra Classic however, with 50k on it doesn't leak a drop! Never has!

Now my buddy's knuckle head on the other hand......
 
The engine rebuild video listed here a week (or so) ago showed a dab of rtv being applied at the case junction when it was crossed with another part, like the sump. The same occurs on a SB chevy where the heads hit the block as the wet bottom manifolds meet there. Same solution. Just use RTV sparingly as a clump in the oil pump will REALLY ruin your day.

The engineers at Conti would not accept leaks, the three engines in the club planes stayed dry. If a leak starts, fix it, was the rule. If you don't, then you will miss the next, and the next, and it will look nasty all the time.
 
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