On 5/9/2005 09:56, xyzzy wrote:

If an engine has been overhauled 3 times, never making TBO either time
(not even making it to 1/2 of TBO 2 of the times), should I be concerned
that it might be a lemon, or if the current overhaul was done right and
the engine has been treated right since then, should I not worry about
how it did before this overhaul?



That's a really good question. Do you have "The Complete Overhaul"
by Kas Thomas? This is a really good book on the overhaul and industry.

Basically, the engine is a collection of parts. Some of these
parts can be replaced during the overhaul. If the cylinders, crank,
cam, etc. are replaced, is it the same engine?

Additionally, these replacement parts came from somewhere. Perhaps
the "new to you" crank comes from an engine that was having all
sorts of problems.

Basically, if the parts all meet tolerances, the engine should
perform as new. So I think the real question comes down to the
work done during the overhaul. Were the parts inspected as well
as they could have been. Was the resurfacing work done as well
as it should have been (or at all), etc.

Based on my reading only, that is what I think makes a good
overhaul. The book is chocked-full of doom and gloom, but is
really a good read - and an eye opener!

To determine why your engine didn't make it to TBO, you may
have to look at the shop that did the work (assuming the
engine wasn't mistreated, of course). Perhaps they have a not
so good reputation?


--
Mark Hansen, PP-ASEL, Instrument Student
Sacramento, CA