Ben E.

cylinder and lifter issues

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I'm looking at a J that had a Western Skyways major overhaul to factory new limits in 2010.  The compressions had dropped to the low 70s by 67 hours SMOH.  Around 120 hours SMOH, the #2 lifter collapsed and overhauled lifters were installed.  The compressions were back to the mid 70s by 250 hours SMOH, but fluctuated between low and mid 70s thereafter.  In 2015 there is an entry that says "R&R all 4 cylinders for repair . . . completed initial break in runs per Lycoming SI1427B, no leaks noted."  The last two annuals had high compressions.  

I asked the owner what happened to cause the R&R on the cylinders and lifters and he said "It was a bad break in. So I hired someone to break it in after the cylinders were redone."  I believe this is only responsive to the cylinders because the lifter issued happened before he owned it.  I've asked for detailed work orders for all work.

In the meantime, I know there are some guys here that know a lot about these things.  What do you think happened and do you think it's something that should make me question the quality of the overhaul and the engine?

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Sounds like the plane has at least been in the air. Too many ads showing 300 hrs from an overhaul in the 90's...

Western Skyways has some mixed reviews and some informed readers really don't like major engine work like this. My opinion is if everything tests well right now and it has been flown a lot lately not to worry about it. 

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See if the lifter issue goes back far enough that it caused the need for the OH.

Planes that sit idle have a chance to get the cam rusty.  The lifter is the thing that rides on the cam.  The business end of the lifter is the cam follower.  It also gets eroded and the rough surface cuts down the cam lobe.

a worn cam is an OH problem because it can't be removed with the engine in the plane.  It requires opening the engine block up...

Use caution, any lifter problem can directly have affected the cam's health.  I've never heard of a collapsed lifter.  They are a simple system of spring, Rod, arm, and cam follower.

write out a time line for yourself...

1) engine got OH'd...

2) break-in procedure didn't work... low compressions for years?

3) Cylinders got resurfaced... new rings, new break in...

4) Then the valve lifter has a problem? What caused that, are there three others just like it?

A good break-in takes about 10 hours to be 90% complete.  The progress can be watched on the engine monitor. The last 10% takes another 90 hours... roughly speaking...

I bet the owner isn't very happy about all of this activity...

PP thoughts only, not a mechanic...

Best regards,


Edited by carusoam

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