found oil on the floor, grounded

[David-aviator]

Thanks for sharing Steve. Sorry this has happened.

I have a Superior 0360, so far it has no leaks anywhere but I know that can't go on forever.

[molson309]

I had a leak on a IO360/Hartzell combination that looked a lot like this. It turned out to be the prop seal. Oil pushed past the seal, past the ring gear, and came out on the back side then was spun out by centrifugal force. Had oil pooled on top of the airbox. I could have sworn it was a leaking crank seal and even got the replacement part for it. When I took off the ring gear and looked the seal was dry. Replacing the o-ring sealing the prop fixed the problem.

You'll know pretty quickly once you get the prop off.

[C-FAH Q]

Slide your fingers around the back of the ring gear so you can touch the seal, it's tight, but you can do it. Wiggle the prop back and forth, you should feel the seal move a tiny bit if it's leaking from there. There are some things you can mess up with the seal installation and the plio- bond if your not careful. Make sure the case is completely free of old plio-bond and clean it well with solvent. Heat seal in boiling water for a minute to make it pliable. Don't over stretch the spring in the seal, it goes on separately. Put a drop of oil on the crank so no adhesive sticks to it. Don't forget to seat the spring back in the seal. Order two seals, they are cheap and sometimes they break when getting stretched, no often, but they do. Let engine sit for a day to let adhesive fully cure, and wiggle the prop a little till it starts to set, don't want it adhearing to the crank.

[lr172]

Originally Posted by AlexPeterson

There seems to be more oil on the floor than could drool down from the cowl. Meaning maybe like something that contains oil is leaking. If that much oil was simply splattered around on the cowl, the belly would have been covered, I'd think.

Good luck! Two types of engines - those that have and those that will leak oil...

I am with Alex here. A front seal will only leak when the engine is running. There is no standing oil in that area after shut down. The amount of oil on the floor is indicative of oil leaking from an area with some volume of oil in it. The prop hub holds a decent amount of oil and I would be looking for a leak there first.

Larry

[rvbuilder2002]

Originally Posted by lr172

I am with Alex here. A front seal will only leak when the engine is running. There is no standing oil in that area after shut down. The amount of oil on the floor is indicative of oil leaking from an area with some volume of oil in it. The prop hub holds a decent amount of oil and I would be looking for a leak there first.

Larry

I somewhat agree but no one has mentioned the possibility that there was a major seal failure shortly before the airplane was put in the hangar. The cowl interior could have been coated with oil but not really noticed until it had drained out onto the floor.

I agree with a previous post that if if it turns out that the seal has had a major failure, the crankcase venting should be inspected. If your last flight was in below freezing conditions, it could have even be caused by an iced up vent tube.
This is pretty much unheard of with RV's if you do the recommended vent installation but if yous is different it is a possibility. Or if you have the vent connected to the exhaust... it is probably time to inspect and see if it has plugged.

The oil in the prop hub has a path to the nose section of the engine (where the front seal is) so if the seal failure was severe enough I think it is possible for oil in the prop to leak.

I agree that removing the prop is probably the best first step. It will need to be off to fix the cause, regardless which is the source of the leak.

[airguy]

Originally Posted by rvbuilder2002

. Or if you have the vent connected to the exhaust... it is probably time to inspect and see if it has plugged.

I know it's been discussed at length, and Allan even has an SB on the separator he sell that plugs into the exhaust, but if you have that you definitely need to check it. As a data point I am currently conducting my first condition inspection and just cleaned mine, with 105 hours of runtime it was somewhere between 1/3 and 1/2 closed off with coked oil. I have an IO360 running mostly WOTLOP with Vetterman crossover.

[Steve Melton]

as found, untouched, front crank seal, there's the source of the leak, the seal was completely free of the case, this is a one piece seal not split







the vent was clear



some kind of grey sludge in there

[YellowJacket RV9]

Wow. I would imagine things could have been much worse - seems like that could lose a lot of oil very quickly in flight. Glad you found it.

Chris

[Steve Melton]

Originally Posted by YellowJacket RV9

Wow. I would imagine things could have been much worse - seems like that could lose a lot of oil very quickly in flight. Glad you found it.

Chris

ditto that! maybe a periodic borescope inspection of the seal would be an action?

[BillL]

The gray matter is stuff in the oil being centrifugally separated in that cavity. That is the reason for pulling the prop periodically and cleaning that area.

The 65-70 honda motorcycles and some Fiats had a slinger on the end of the crankshaft that did this job. The material had to be chiseled out if left too long without service.

Glacier.