IO 360 LESSIONS

[ELT]

 The engine was 19 years and 700SMOH (I owned it the last 6 years and 300 hours) (Yes, I know about low usage and years but many airplanes have similar utilization.)    The engine had a small oil drip leak which was diagnosed by 3 different shops as case half leakage and common in the IO-360.   I was told it helped keep the corrosion down.  The engine also had a skip when taxiing after landing with a hot engine.  This was diagnosed as fuel vaporizing in the injector lines and common to the Mooney.   Compressions were OK and oil usage low.  No metal in filter at 25 hour changes. I use an engine analyzer.

TAILWIND AVIATION and I planned to do a landing gear rework and powder coat.  I wanted to stop the oil drip on the nice new gear so we planned to epoxy the case.  Unfortunately, when the alternator and other parts were removed we discovered a cracked case.  The engine was removed and sent to AERO ENGINES of Winchester.  Upon tear down the camshaft was pitted and the lobes worn.  Other problems were found in the engine.  The engine was not long to a failure. The result was almost all engine parts except the crank replaced with new or different tagged parts.  Tom at AERO ENGINES was great to work with.

During the engine reinstall Kevin at TAILWIND AVIATION noted that he did not like the bracket attaching the STCed alternator to the engine case.  He researched the STC and found that the bracket was not correct.  Tom and Kevin theorize that the improper bracket caused the engine case crack.  Good catch Kevin!   Tom shipped us a new Plane Power alternator and bracket.

I put about 5 hours on the engine this weekend.  Almost no oil usage, temperatures dropped at 3 hours.  No engine skip and very smooth.  Thanks to Kevin, Tom and my wife.

Lessons:  If you have an oil drip find it.  That skip may not be due to fuel vaporization.  Check your STCed alternator bracket.   Fly the airplane often and keep the corrosion down.   Retirement is postponed if you own an airplane.

[Parker_Woodruff]

Glad you can now be confident behind your engine.  Are you attributing the "skip" to the worn cam? any increase in climb performance?

[ELT]

Yes, we think the skip was due to valve train problems.  Too soon to tell on climb.  We did install a new not reground cam.

[jetdriven]

hope you used new lifters too.   There sure seems to be a high incidence of case cracking at starter, generator, and alternator mounts.  That gives me the willys.

[ELT]

Yes, new not reworked lifters.  The Plane Power brackett design looks much better than the even the correct brackett for the other alternator.

[jetdriven]

Hmmm you got me worried. I have the stock J Kelly alterntor bracket.  Should I change it?

[ELT]

What was in my plane was an Interav STCed alternator.  The alternator appeared poorly supported several inches from the case even with their proper brackett.   A ruff hot start had to make it shake pretty violently.