miyu1975

miyu1975

Well Known Member
I have noticed when I take my cowling off that I have a small amount of oil on the inside of the cowl that is basically right on the inside where the prop would be spinning...(hard to describe)..I have determined that is coming from the prop where it meets the flange of the engine. I spoke to the prop shop who did the reseal on it and he said that I probably buggered up the o ring inside the prop hub that slides over the engine flange (because I put it on dry) as the reason for this...so he sent me another o ring. I pulled the prop and put the new o ring on and this time used a little grease on the o ring before reinstalling the prop. Went flying tonight for .8 hr and pulled the cowl and dang it I still have a small amount of oil again...same area. Not sure what to do now, besides take it to the prop shop... any ideas?
 
Hi Ryan,

I am currently fighting the same problem. It started about 100 hours ago after 700 hours of no trace of oil. It definately eminates from the interface of the prop flange and the forward face of the ring gear. I have replaced the prop o-ring twice only for the slight seep to appear again. The prop flange shows no scratches, the bore and the o-ring groove are perfectly smooth and so is the lip of the crank shaft. Each time I lubricated the o-ring with silicone grease before installation. I examined the removed seals with a magnifying glass and found no damage to them. The oil shows up on the wind shield as a very fine mist after a few hours of flying. I will keep working on this issue until it is resolved and post the results here when I get there.

Martin Sutter
Building and flying RV's since 1988
EAA Techniclal Counselor
 
I suppose it could be from the crank shaft main seal...actually I was thinking that this morning too. While inspecting the engine/prop area I havent found a trace of oil any where except on the cowling. If it is the crank case main seal I should find some oil on the rear of the starter ring, right...so I will investigate that.
 
Ryan, take some absorbent paper towel or something and duct tape it around the crank nose seal, so that it will suck up any oil before it goes anywhere. Fly the plane with a clean cowl and engine. Then check your diaper. Often they can leak without leaving a trace in the ring gear. If that comes out dry, measure the length of the crank O-ring nipple from the flange face to the start of the edge bevel. Then measure the depth of the prop O-ring from the hub mating surface.
 
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