Hi Jeff,

 

If your aircraft is perhaps a taildragger (I can’t recall) and sits so that the oil at the back of the pan is over the pan/block seal, you may want to reconsider using a gasket.  I have a “Plugs U” installation with a sump below the block, so the oil flows over the pan/block interface before flowing into my sump.  When I used a gasket, I found that the gasket would eventually become saturated with the oil and after a time began a slow dripping leak.  Very slow, but a little oil on the bottom of the cowling goes a long ways. 

 

I stopped using the gasket and use the Grey Silicon sealant (Permatex brand I believe) make for oil tolerance and that solve my problem of the dripping oil.  Don’t know if this could apply to your set up but thought I would mention it.

 

Ed

 

Steve, the string idea is a good tip.

Sounds like no one is voting for the gasket, favoring Ultra-Grey sealant. Since I’ve already paid for the gasket (can’t return it) I’ll use it if not too thick.

 

Originally I put the pan on with bolts just snug, allowed silicone to set for 24 hours then tightened them. My oil pan is modified - with the indentation for inner mounting bolt removed and an external cover panel allowing for more oil. It is leaking just behind the two large (10mm?) mounting bolts and not at the rear edge … maybe there is a slight warp or imperfection from the modification.

Jeff

 

 

All,

 

For what it is worth, I had a slow oil leak between the oil pan or the block and the mounting plate the first time I assembled it in spite of cleaning the surfaces well.  The second time I put things together, after cleaning all the mating surfaces several times with brake cleaner, I embedded a light cotton string in the Ultra-Grey on both sides of the mounting plate.  This allowed me to tighten the oil pan bolts without squeezing out all the sealant from the joint.  This would be somewhat similar to the use of a silk thread between the case halves on a conventional  aircraft engine.  I realize that this is a limited data set (one instance) but at least I don’t have oil leaks in this area so far.

 

Steve Boese

RV6A, 13B NA, EC2, RD1A

 

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