Leaky crankshaft oil seal?

Had some down time this weekend due to the rainy (unusual for SoCal) weather, so I decided to pull off the cowl and do some minor maintenance on the engine. Engine is an IO-320 E2D solid crankshaft with 18 hours since full overhaul. I'm assuming the oil ring at the front of the cowl is due to a bad or leaky crankshaft seal, but figured I'd post this to get the advice of the VAF collective. I changed the oil at 10 hours and put 6 quarts in and the oil level really hasn't changed at all, so what you see on the cowling is very little oil, but enough to make a bit of a mess. I've consistently had a bit of a oily streak in the same location during the previous flight hours, but haven't had the cowl off since the oil change at 10 hour, so this is 8 hours of leakiness and in the previous flights I had the cowl on and off more often.

Is this seal messed up and should I replace it now, or can it wait?

Bottom cowl.



Top cowl.



The flywheel and starter ring gear don't seem to be oily, but it just may be all flung off as it leaks.

One piece or two piece seal? How long did the engine sit before running? Even the smallest of burrs on the crank flange can damage a one piece seal. and two piece seals are junk. Heck, the spring may have even come off the seal.

One piece seal installed and the engine sat for about 15 months before first start after overhaul.

I say either the flange got the seal with a nick, or the spring came off. Looks like a little amount of oil, fly it and keep an eye on it. As long as the seal has not blown itself out, you should be okay for a little more testing.

Are you sure it is coming from the crankshaft seal? Most of the time a leaking crank seal will sling the oil outward enough to coat the inside of the starter ring gear/flywheel. I have seen a crankshaft seal weep oil between the O.D. of the seal and the case, and in this case the oil ran down the case seam and did not coat the inside of the ring gear.

I've read and experienced that a leaky nose seal can occur during the first hours of operation. It needs to seat just like 90% of the other parts in the engine. I'd clean it all up and fly some more to see if it continues to leak.

The only way to really tell if it is the nose seal leaking is to visually inspect. Which means you have to remove the prop and ring gear. (A real hassle if you have a CS prop.)
In my opinion, the leak will not go away by itself.
I have installed quite a few nose seals, both split ring and one piece and have not had issues with either. But, they must be installed correctly.
If you aren't sure about how to install the nose seal, seek out someone who knows how to do it correctly.

I will get the engine builder to take a look at it. I watched him install it the first time around and it seemed like he knew what he was doing (he has been doing this for about 50 years!).

Thanks everyone!

Sid Lambert said:

I've read and experienced that a leaky nose seal can occur during the first hours of operation. It needs to seat just like 90% of the other parts in the engine. I'd clean it all up and fly some more to see if it continues to leak.

Click to expand...

+1.

I had mine leak starting a few hours after overhaul and disappearing a few hours later.