still chasing oil leak near prop. opinions appreciated.

[rbridges]

I replaced the crankshaft seal and o-ring in December. It was a split seal. It seemed to help but still getting oil leak. Took it back and they inspected it but didn't replace it. Flew it for 10-12 hours with no change. I just had it replaced with a solid seal by another IA, and it seems to be leaking worse.

It sat for several days after the last seal change. I ran the engine for several minutes. I also ran the prop up to 1800-2000 rpm without cycling it. Oil temp got up to 130-140F. No leaks whatsoever. I ran it a second time, but this time I cycled the prop. That's when it started leaking. Does that necessarily mean anything?

I'm hoping I'm just having bad luck with the seal, but you start worrying about the worst case scenarios. It's a Lycoming O360 with 1150 SMOH. Just completed annual at an MSC and looked great besides the oil leak.

 

[edessa]

I would look at the prop it self and not the crank seal. I have had a few over the years leak at the blade to hub seal and get worse over time. Oil would get everywhere. Just a thought.

 

[rbridges]

I would look at the prop it self and not the crank seal. I have had a few over the years leak at the blade to hub seal and get worse over time. Oil would get everywhere. Just a thought.

thanks for that, but I just had my prop sent off for repairs. It had grease leaking out of the hub. It's ironic but my oil leak started after the prop was repaired.

 

[Dan Thomas]

There's an o-ring in the prop hub that seals on the crank nose to contain the oil pressure to the prop. When you cycled the prop that seal was put under pressure when oil was sent to the hub to increase pitch. The o-ring is nicked or out of place. Prop has to come off again.

 

[JAWS]

There's an o-ring in the prop hub that seals on the crank nose to contain the oil pressure to the prop. When you cycled the prop that seal was put under pressure when oil was sent to the hub to increase pitch. The o-ring is nicked or out of place. Prop has to come off again.

Yep. Time to look at other possibilities.

I have used roasting bags (good for high heat use) to isolate engine components while troubleshooting.

 

[rbridges]

There's an o-ring in the prop hub that seals on the crank nose to contain the oil pressure to the prop. When you cycled the prop that seal was put under pressure when oil was sent to the hub to increase pitch. The o-ring is nicked or out of place. Prop has to come off again.

I'll check again .It looked like the leak was coming from the crank seal .Could a leaking o-ring cause oil to push back towards the rear seal?

 

[Dan Thomas]

I'll check again .It looked like the leak was coming from the crank seal .Could a leaking o-ring cause oil to push back towards the rear seal?

It will appear at the interface beteen the crank flange and prop hub. Sometimes the spinner backplate is wet.

I wonder if the guy installing the crank seal got some goop in the oil drain hole behind the seal. The oil coming off the front bearing needs to drain that way. It was your comment that the leak started when the prop was repaired and reinstalled. That's normally a problem with that prop hub o-ring.

See that little black thing labelled "Shaft O-ring?" That's it.

 

[KRyan]

+1 on the prop o-ring. Another thing that happens sometimes is a bit of "crud" gets between the hub and the o-ring (rather than between the hub & the shaft), so if you end up taking the prop off the troubleshoot, take the o-ring out and clean the groove in the hub. Also, on Continental installation with Hartzell propellers, the o-ring groove can get damaged during installation of the propeller. Don't know if the same thing can happen with McCauley props, but I think it can. Both manufacturers have a repair for this, but hopefully that's not your problem.

 

[rbridges]

thanks for all the advice.

 

[Cherokee Lover]

Did u ever figure out what was causing ur oil leak? BTW...I am from WR also and having the EXACT same issue!
Maybe we used the same shop...LOL

 

[3393RP]

If the leak started after the prop work, that's a pretty sure thing. I'm surprised the OP dismissed the connection between the two.

It's ironic but my oil leak started after the prop was repaired.

 

[rbridges]

It turned out to be a combination of both seals. The last repair slowed it down but photos revealed steaks coming from the front. It also eventually stopped. We surmised it was oil that wasn't completely removed when it was reassembled.
The last person spent a lot of time cleAning the crankshaft, and I think that was the difference .