Overhaul of 180HP Lycoming 0-360-A4M in a Skyhawk (C-172)

Thats a tough call.....

Our 172 was purchased from a training school that put 2500 hrs on it
in 4 years.

It started making metal at 2792 hrs. (aft cam lobe)

Was using a liter of oil/12 hrs, comps 72 - 75, good oil pressure,
pulled great..

Replaced engine, could not tell the difference in oprn or
performance..

At the flight school, if they could see, they flew.. the aircraft was
very agressively maintained. Cosmetically, it was rough, but
mechanically, no concerns, Annuals.... cowl fasteners and a manifold
flange leaking (exhaust) were the biggies. Squawked one time for a
noisy wheel bearing.

Dave



On Fri, 13 Jan 2006 17:17:09 -0500, "pgbnh"
wrote:

Maybe a related question.
How to make the decision to actually DO an overhaul/replacement?
In some cases it is exceedingly clear - lots of metal in oil, oil usage,
cylinders blown, etc.
But what about the high time engine that is otherwise working just fine?
Compression good. Oil clean. not burning excessive oil.
Due to a prop strike, my lycoming IO360 was torn down at 1300 hours. Since
it was in pieces, we did more than a 'normal' sudden stoppage inspection.
Bearings, cam recondition, rings, etc etc.
Engine is now at 2400 hours (2000 tbo). Runs fine. No change in oil
consumption or fuel consumption. Good compression. Do we wait for bad stuff
to happen, or be proactive. Frankly, I am concerned about taking an engine
that 'ain't broke' and either overhauling it or replacing it and ending up
with problems when today I don't have any.

any advice on how to know when 'It's time'?
"Andrew Gideon" wrote in message
gonline.com...

I'm the "plane lt." for a skyhawk, based in northern NJ (KCDW), that's
getting ready for its engine overhaul. What should we do with it?

I'm curious what others have done, and how its worked for them. I've been
doing some of reading of articles, but it's raised more questions than
answers. Questions I do need, but I'd also like some of those answers.

Questions bouncing around head include:

Should we get our engine overhauled, or swap it for a previously
overhauled
engine?

If we do overhaul, is "to new specifications" the only reasonable choice?

Is there a difference of significance between "factory rebuilt"
(zero-timed)
and "overhauled to 'new specifications'"?

Any recommendations for shops for the overhaul (or shops to avoid)?

Finally, I'm confused about the process. Does one shop remove/replace and
another actually do the engine work? Or does the plane need to be flown
to
the shop that either does the overhaul or has the engine to swap?

For others asking similar questions, here's some of what I've read:

http://www.mattituck.com/new/articles/ohterms.htm
http://www.avweb.com/news/maint/185049-1.html

http://www.aviation-consumer.com/arc...rt/4718-1.html

I've also looked through the forums on cessna.org, but I cannot relocate
what I'd previously found there.

Thanks...

Andrew

But what about the high time engine that is otherwise working just fine?
Compression good. Oil clean. not burning excessive oil.

My opinion is that if you have a properly working engine, no need to
overhaul it. There is some risk in flying it, but there is risk in
overhauling. The breakin period is risky time to fly. Spending all that
money is risky. There are risks everywhere.

I have an engine that is 2200 hours since new, never overhauled or
rebuilt. I am monitoring its oil filter and doing oil analysis at every
oil change. I think the risk/reward tilts toward just keep flying it
until I start using oil or metal wear shows up or the compressions go
down. My engine just keeps on ticking.......why risk replacing it?