How many times can an engine be overhauled...

[Michael Burbidge]

I'm looking at a midtime TSMO engine. It looks like a solid engine and was overhauled by a very reputable engine shop two years ago. The only drawback is that it has about 4500 hours TT.

Should I be concerned about that number of hours? Do engines typically have a limited life in terms of number of overhauls?

Thanks,
Michael-

[RV6_flyer]

My engine has been overhauled twice since I owned it and once before I purchased it. There is over 5,700 hour on it and it is still going strong.

An engine can be overhauled as many times as new replacement or new spec replacement parts can be obtained.

IMHO, an overhaul should be overhauled or rebuilt to NEW specs if you want the engine to last to manufacturer's TBO.

[Remag]

It's most likely like my grandfather's axe. The axe was handed down to my father and then on to me. It has only had six handles and five heads but still works as well as the day he purchased it

[jetdriven]

I read somewhere that the life of cylinders was about 4-5000 hours and the fatigue life of the crank and rods was somewhere like 8-10K hours. The case after 2-3 TBO cycles gets milled to limits and wont pass anymore.

[rhill]

How long has it been since this engine was airborne?Any logs?Prop strikes? How many times has it been overhauled? once or twice. If it sits too long the carbon gets hard and the valves stick. What about the carb&mags? Lots of questions here,we need more info. 4500TT by itself is not a deal breaker,Price is always a factor.

[AK4x4]

There is no limit to the number of hours or number of overhauls on an engine. I would recommend that during any overhaul everything should meet limits for new parts and new (not overhauled) cylinders should be installed. If this is done (standard practice at better shops) the engine should go to TBO every time. Of course with successive overhauls it will become necessary to replace various parts in order to meet the new part limits and eventually you could have replaced every part in the engine with a sufficient number of overhauls. The grandfathers axe analogy would apply at this point. For the engine in question I would not be concerned about the total time but would be concerned about the quality of the most recent overhaul and how the engine was used/stored during subsequent years.

Good luck
Russ

[Michael Burbidge]

The engine was last overhauled in 2009 by Triad Aviation. Since then it has flown regularly for a total of about 1000 hours. I have full logs. No problems, no leaks sine the overhaul. Last flew a few weeks ago. Regular oil changes. The only red flag I can see in the logs is that a crack was repaired in the case by Divco at last overhaul.

[MauiLvrs]

Originally Posted by Michael Burbidge

...The only red flag I can see in the logs is that a crack was repaired in the case by Divco at last overhaul.

Expect that this may be an issue in the future...

[pierre smith]

An old-timer A&P/IA once told me that he'd rather have an engine that has gone through at least one cycle, since it is now "seasoned"...all the molecules are aligned and if it hasn't cracked the case by now, it probably wouldn't.

....said he'd rather have that than a new (unkown) case

Best,

[Fearless]

I'd look at the case real close to make sure no cracks existed. It wasn't until I sent my case out for service on my rebuild that I got the wonderful news that the case had cracks and was unserviceable. Which I incurred an additional expense I hadn't planned on or desired. The core I bought had numberous rebuilds on it which I wasn't aware of and I was under educated on what questions to ask before I purchased it. Looks like you are trying to ask the right questions and do the right thing. I bought mine off an ad in Barnstormers from a shop in Florida some years back. Live and Learn