Engine exceeds TBO

Thanks Jim for making it so clear and understandable.

Jean-Paul
Quebec, Canada
"RST Engineering" wrote in message
...

"Steve Foley" wrote in message
...

Yup. It's run out,

No, it is not "run out" whatever you mean by that statement. It is still
holding compression, not making metal, and does not have excessive oil
consumption.


and will need replacement/rebuilding shortly.

Really? And what diameter was the crystal ball that you used to make this
determination? I've seen engines that have been taken care of go DOUBLE
TBO. I've seen abused engines go HALF TBO. It is strictly a function of
the care and feeding of the engine.



How should I approach this engine ( i.e. just assume everything over
1800 hours was a freebee and there is no guarantee it's not about to
poop out

Engines don't "poop out". Engines have a slow, steady slide into required
serious maintenance. Every now and again, one will have an unforeseen
catastrophic failure, but those are few and far between.

The other side of that coin is that bearing/crankshaft wear tends to
become
exponential after a point in time when it departs from linear. That is,
for
a long time (extrapolated by the manufacturer to be "TBO") the wear on the
bearings and the crank is linear. At some point when the bearings get to
be
sloppy on the crank, the wear accelerates, and the faster it accelerates,
the faster it accelerates. If you want to play the crankshaft roulette
game, you extend TBO until the bearings start to make metal. Then you
pull
the engine down, and if you are lucky, the bearings (the cheap part) took
the hit and left the crank journals intact. If you lose, you grind the
crank UNLESS somebody else played crankshaft roulette before you and the
crank had already been ground to minimums. Now you REALLY have a rough
row
to hoe, in that you get to find a replacement crank ... which ain't cheap
by
anybody's standards.

Jim