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Lycoming cam/follower wear

Urp99

Well-Known Member
#1
Looking for some opinions here ...
I'm helping out a friend doing a top on the IO-540's in his Aztec. Long story, but I got involved after everything was disassembled, gotta love taking over half way through a project like this :p
Anyway, after inspecting the bottom end I found some very minor spalling on the followers and the associated strange wear marks on the camshaft. It's nothing you can feel with a finger or fingernail, but you can feel 'roughness' when you slide a pick across the face of the follower. Another mechanic has looked at it and thinks the case should be split, cam re-surfaced or replaced, and new followers installed ... I'm of the opinion that this type of wear is normal for a mid-time Lycoming, and that there's a lot of life left in the bottom end for an airplane that's flown recreationally. I'm also concerned that if we keep digging into the engines we'll keep finding things wrong, and end up needlessly majoring this guy's engines.
Any opinions from the engine experts out there? I want to help this guy out, and get him back into the air without breaking the bank, but I don't want to see him tearing into the engines again soon either ...
 

pilotmec

Well-Known Member
#2
IMO:
Once a Lycoming cam and lifters start to wear, it's only a matter of time.
I put reground cam in a 540 once and it only lasted about 400 hours so I redid it with a new cam and lifters. Never again.
 

Urp99

Well-Known Member
#4
Once a Lycoming cam and lifters start to wear, it's only a matter of time.
I put reground cam in a 540 once and it only lasted about 400 hours so I redid it with a new cam and lifters. Never again.
I'm not a fan of reground cans either, mainly because I don't have much faith that they'll be hardened correctly. I also agree that any engine part that's wearing will continue to deteriorate, the only question is how long it has left (of course that's true with a new cam too!).
How much time is on the engine SMOH? What's the reason for the top?
It's a mid-time engine, right around 1000 hours. I'm really not sure why they decided to do the top, I think it basically comes down to the fact that they were old original cylinders, they were overhauled, flown 1000 hours, then sat for 10 years, and the new owner wasn't comfortable without getting a good look inside the engine and putting new cylinder assemblies on
 

trafficinsight

Well-Known Member
#5
I'm not a fan of reground cans either, mainly because I don't have much faith that they'll be hardened correctly. I also agree that any engine part that's wearing will continue to deteriorate, the only question is how long it has left (of course that's true with a new cam too!).

It's a mid-time engine, right around 1000 hours. I'm really not sure why they decided to do the top, I think it basically comes down to the fact that they were old original cylinders, they were overhauled, flown 1000 hours, then sat for 10 years, and the new owner wasn't comfortable without getting a good look inside the engine and putting new cylinder assemblies on
"sat for 10 years" is the dead giveaway here.

It's time for an overhaul.

Sorry.

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trafficinsight

Well-Known Member
#7
I agree, ten years sitting for a Lycoming means it's time to overhaul.
I've put engines back in service after longer and had them go to TBO, but when you couple it with the cam wear it's pretty likely that there are other issues.

Good money after bad.

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Vector

Well-Known Member
#8
I'm not a fan of reground cans either, mainly because I don't have much faith that they'll be hardened correctly. I also agree that any engine part that's wearing will continue to deteriorate, the only question is how long it has left (of course that's true with a new cam too!).

It's a mid-time engine, right around 1000 hours. I'm really not sure why they decided to do the top, I think it basically comes down to the fact that they were old original cylinders, they were overhauled, flown 1000 hours, then sat for 10 years, and the new owner wasn't comfortable without getting a good look inside the engine and putting new cylinder assemblies on
Lycoming engines that have been left sitting are a hit or miss because of the placement of the cam. Corrosion is much of a concern not spalling. Splitting the case is not a bad idea but a full blown overhaul is not necessary if there isn't noticeable wear. Remember once you split the case, you have to comply with Lycoming's overhaul replacement list. At that point in time, you are biting the overhaul bullet. If I were you, I would get 2 or 3 independent opinion before coming up with a cause of action,
 

BigZ

Well-Known Member
#9
Did the engines get any time on them after sitting?
With the Lycoming camshafts, if they decide to go (as in, corrosion attacks the hardened surfaces which results in excessive wear of the lobes or whatever out call those things in english), that usually happens within 100-200 hours after returning to service.
Tiny needle-like pieces in the oil filter would be a good giveaway that's what's happening.