How much time is too much?

[Don Patrick]

Just curious what some would consider too much time on an used engine? I've seen some engines out there with 3000 hours up to 6600 hours for sale. If all the crank, case and cam and everything checks out, should buyers beware of high time engines?

Thanks

Don

[pierre smith]

Don, an old mechanic once told me that he'd much rather have a rebuilt, runout engine. He said that all the metal, including the case, had been "seasoned" from all the heat cycles and the case was more of a sure thing than a brand new, unproven case.

You don't say whether the seller is willing to guarantee the crankshaft or cam either. That would be a deal breaker if he refuses.

Best,

[DanH]

Originally Posted by pierre smith

Don, an old mechanic once told me that he'd much rather have a rebuilt, runout engine. He said that all the metal, including the case, had been "seasoned" from all the heat cycles and the case was more of a sure thing than a brand new, unproven case.

An old engineering professor once told me that all aluminum is simply frozen mush, and given enough stress cycles it is guaranteed to return to mush.

What he meant, of course, is there is no knee in the S-N curve for aluminum. Although there may be a reasonable argument for achieving dimensional stability after use, such seasoning has no bearing on fatigue life.

[David-aviator]

There is a lot more junk than good stuff for sale in the used market. Buyer be mighty beware.
It isn't like it was when thousands of light aircraft were being built and sold with new engines. The source of good used engines has gone south.

[Don Patrick]

Thanks for the info guys, much appreciated.

Don

[tim2542]

Buy a kit engine if you can swing it. Unless you get a very good deal on a used or run out core....and you KNOW everything will yellow tag, by the time you do a correct overhaul on it you will be pretty close to kit cost and still have a field overhauled engine worth much less.
My 2 cents
Tim

[Toobuilder]

Originally Posted by tim2542

...by the time you do a correct overhaul on it you will be pretty close to kit cost and still have a field overhauled engine worth much less...

Depends on your definition of "close" to kit cost. Kit engines typically seem to run about the cost of a factory new engine less the labor to assemble.

As for "correct" O/H, you might get lucky and see the expensive innards well inside the service limits and therefore only need a good inspection. In this case, then you are well under a kit engine in cost and still just as good.

There is a lot of junk out there though, so you need a little luck as well as knowledge.

[tim2542]

When I built my engine I could have bought a kit engine w/o accessories for around $18 k and I got within 2k of that with core. So it's back to do all due diligence before writing a check.
I'm just using my hind sight, others will of course have better or worse results.
Like others have said, be careful, very careful.
Tim