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It's only money

txpacer

SPONSOR
Iowa Park, TX
520 hours since overhaul less than four years ago. I think maybe they were reconditioned one time too many.

New parts going in this time.20190830_085331.jpeg
 

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It has been years since I was performing a lot of Lycoming engine overhauls. At that time those lifter assemblies were always thrown away and replaced with new.
 
I have seen folks regrind what looks to me to be very serviceable tappers and cams. I think, without any evidence, that regrinding removes something important.
 
Intake, exhaust, or mixed?

Gary
Looks like a complete engine's worth. Why are four of them destroyed and the other four just starting? That is the mystery to me. What else was happening in that engine to cause that extreme damage to just those four? Exhaust valve guides too tight? Something else?

txpacer, I would want to look into the questions which I have addressed prior to reassembling that engine. If all eight were the same, I wouldn't be asking.
 
Pete, I have seen the same more than I care to remember. Reground cams and lifters do take away the hardened layer. They are prown to corrosion and once they get any pits it doesn't take long. I am told that the DLC (diamond like coating) that Lycoming is now using has eliminated this issue. Time will tell.

The 4 really bad followers were on 2 cam lobes. It was a reground cam and followers but being replaced with new cam, follower, hydraulic unit kit so am hoping this engine goes to TBO without any issues.
 
I think the simplest explanation is the most likely cause - the yellow tagged tappets were past their useful life and failed.
 
I think the simplest explanation is the most likely cause - the yellow tagged tappets were past their useful life and failed.
I think that the person who placed the yellow tag on the tappets needs to rethink what he is doing since he certainly didn't do you any favors. Those tappets should have gone to the full TBO or in the trash rather than the crankcase.
 
We Rotax 912 fliers get confused by posts like this, or at least this one does, like the other recent one of 0-200s blowing oil. With all due respect, all long as these legacy engines have been around, I'd think they'd have this all figured out decades ago. The next time the Austrian powerplant gets dissed, keep it in mind y'all! My own easily made the 2000 TBO,, while doing about half of the factory recommended maintenance,FWIW.
 
I ran Camguard since the overhaul and pickled it with ESO while the plane was down for rebuild. The cam is clean, except for the physical damage from the bad tappets.
It looks like corrosion played a role. How bad is the cam?
 
I enhanced the pic of the lifter bodies. The four on the right are in better shape. I'd still like to know if the failed units were intake or exhaust. Unless noted otherwise I'll assume they were exhaust, and if so, they may have experienced higher pressure under load (?).

Gary
 

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