IO 360 Crank seal

[ugmech]

I bought my 1970 M20F 3.5 years ago with aprox. 400hrs on a rebuilt engine (prop strike) and one year later with about 500 hrs on the engine the crank seal started leaking & was replaced by a MSC. Now just 2 years & about 270hrs later the seal has started leaking again. The previous time it was replaced, the AME checked crankshaft end play & run out, both were in specs. Is this an ongoing problem with Lycoming engines? I owned a C152 before this & noticed in the logs that the cranl seal was replaced several times before we acquired the plane ( Lycoming 0-235). I always run the engine at the specs called for in the oringinal POH & use the oil that the MSC recomends. Any one have any ideas on this?

Thanks

Ron 

[N201MKTurbo]

 

Read this article:

http://www.sacskyranch.com/eng203.htm

 

 

[Parker_Woodruff]

I had to get mine replaced at annual this year.

[takair]

I don't think this is a common problem, but there are some things that can accelerate leakage.  Improper installation is one thing that will accelerate a leak.  I had a really bad experience after overhaul.  The seal would start leaking every 20 hours.  After the 4th seal, the case was replaced.  Best I can tell, the case was line bored off center.  The company who did the overhaul honored the warranty, including pulling and installing the engine.  They were first class in spite of the problem.  The seal was wearing severely on one side.  Before the overhaul the seal was good for over 1500hrs, and since case replaced we have been good for over 400 hours (knock on wood).  Don't mean to scare you, in most instances it is just a seal that was not installed quite right.  The area is hard to get at, requires cleaning of oil, so the adhesive can work and the seal is easilly damaged on installation if not done correctly.  As I recall, depending on the engine you may have a split seal.  Some folks preheat the seal in oil.  Hard to believe the adhesive has a chance in this case.  All that said, I have only done a few.  Recommend you consult with a good engine shop if you have on going problems.

[rdv]

When we are talking about leaking cranks seals, how much oil loss did you see before the decision was made to replace the seal? Is there any risk of catastrophic failure with this seal?

Ryan

67 f

[takair]

I never lost much because the windshield would get so oily that it was distorting vision. I would notice spots initially then after a few hours it was such that the end of each flight was not comfortable due to the oil.  I think you would need the seal to come out completely before it becomes catastrophic.  The oil on the windhield will cause you to change it out sooner.  (I don't have cowl closure, don't know if the same symptoms apply with a closure)