Overhaul !!!!! ??????

[Charles Talleyrand]

My local mechanic says that I need to overhaul my engine. It's got
1200 hours but it's been 27 years since the last overhaul. He's
worried about the age, and he hears "piston slap" when he runs the
engine. Compression and oil analysis are fine. He is well respected
around the local airport.

He proposes either a name brand $16,000 overhaul, or a less costly
option where he and a local aviation mechanic professor can work on it
together ("two eyes are better than one" he says).

If it makes a difference, I don't live in farmland. I live in the
forest, with forest and lake for 100 miles in every direction.

Any advise? Any way to explain to the wife? Anyone want a nice C-150
with a new paint job but a tired engine?

[dave]

Charles Talleyrand wrote:
> My local mechanic says that I need to overhaul my engine. It's got
> 1200 hours but it's been 27 years since the last overhaul. He's
> worried about the age, and he hears "piston slap" when he runs the
> engine. Compression and oil analysis are fine. He is well respected
> around the local airport.
>
> He proposes either a name brand $16,000 overhaul, or a less costly
> option where he and a local aviation mechanic professor can work on it
> together ("two eyes are better than one" he says).
>
> If it makes a difference, I don't live in farmland. I live in the
> forest, with forest and lake for 100 miles in every direction.
>
> Any advise? Any way to explain to the wife? Anyone want a nice C-150
> with a new paint job but a tired engine?

If the mechanic is accurate and you have piston slap, why not identify
which piston is making the noise and repair only the parts that need
attention.
If the bottom end is solid, there is no reason why you can't get many
more happy hours out of it.

[[email protected]]

On Sep 17, 12:41*pm, Charles Talleyrand > wrote:
> My local mechanic says that I need to overhaul my engine. *It's got
> 1200 hours but it's been 27 years since the last overhaul. *He's
> worried about the age, and he hears "piston slap" when he runs the
> engine. *Compression and oil analysis are fine. *He is well respected
> around the local airport.
>
> He proposes either a name brand $16,000 overhaul, or a less costly
> option where he and a local aviation mechanic professor can work on it
> together ("two eyes are better than one" he says).
>
> If it makes a difference, I don't live in farmland. *I live in the
> forest, with forest and lake for 100 miles in every direction.
>
> Any advise? *Any way to explain to the wife? *Anyone want a nice C-150
> with a new paint job but a tired engine?

Those little Continentals have a weak top end. At 1200 hours
it's not unusual to need a top overhaul: rings might be OK but the
valves should be cleaned up and the lifters will be sludged up and can
be cleaned from the outside of the case. The mechanic might be hearing
valve clatter rather than piston slap, and when the cylinders are off
the dimensions can be checked to eliminate that anyway. I'd bet that
the last overhaul was a hone-and-rering job and that the cylinders are
at service limits now, maybe even .010" oversize and would need
expensive replacement with new ones.
Sludged lifters are cause by too many short flights or running up
on the ground. Crankcase condensation mixes with the oil and creates
sludge (bad) and acids (really bad). The cylinders might be pitted.

Dan

[Steve - KDMW]

On Sep 17, 2:41*pm, Charles Talleyrand > wrote:
> My local mechanic says that I need to overhaul my engine. *It's got
> 1200 hours but it's been 27 years since the last overhaul. *He's
> worried about the age, and he hears "piston slap" when he runs the
> engine. *Compression and oil analysis are fine. *He is well respected
> around the local airport.
>
> He proposes either a name brand $16,000 overhaul, or a less costly
> option where he and a local aviation mechanic professor can work on it
> together ("two eyes are better than one" he says).
>
> If it makes a difference, I don't live in farmland. *I live in the
> forest, with forest and lake for 100 miles in every direction.
>
> Any advise? *Any way to explain to the wife? *Anyone want a nice C-150
> with a new paint job but a tired engine?

Go read Mike Busch's articles on engine overhauls at www.avweb.com or
http://www.savvyaviator.com/articles.html. He has a lot of great
advice. I can guarantee you the advice he would give you for your
engine (read article #9 on his website) would be to replace what needs
to be replaced. An overhaul without bottom-end problems is a waste of
money.

Steve
KDMW
PA28-151

[Denny]

My 30+ year old Lycoming 4 banger had 1650 hours SMOH with a weak
cylinder and solid oil pressure and no sign of bottom end wear.. I
chose to do a TOH and just put 4 new cylinders on and it is running
like new... I second the advice to IRAN...

denny

[[email protected]]

On Sep 18, 3:30*pm, Denny > wrote:
> My 30+ year old Lycoming 4 banger had 1650 hours SMOH with a *weak
> cylinder and solid oil pressure and no sign of bottom end wear.. I
> chose to do a TOH and just put 4 new cylinders on and it is running
> like new... *I second the advice to IRAN...
>
> denny

When you pull the cylinders off, you can look at the cam and followers
to see what the corrosion looks like.

That is the enemy of the IRAN approach.

bh

[Denny]

On Sep 22, 1:24*pm, " >
wrote:
> On Sep 18, 3:30*pm, Denny > wrote:
>
> > My 30+ year old Lycoming 4 banger had 1650 hours SMOH with a *weak
> > cylinder and solid oil pressure and no sign of bottom end wear.. I
> > chose to do a TOH and just put 4 new cylinders on and it is running
> > like new... *I second the advice to IRAN...
>
> > denny
>
> When you pull the cylinders off, you can look at the cam and followers
> to see what the corrosion looks like.
>
> That is the enemy of the IRAN approach.
>
> bh

Ummm, IRAN means Inspect and Repair As Necessary... I doubt that
makes it the enemy...

cheers
denny

[Mike Spera]

Charles Talleyrand wrote:

> My local mechanic says that I need to overhaul my engine. It's got
> 1200 hours but it's been 27 years since the last overhaul. He's
> worried about the age, and he hears "piston slap" when he runs the
> engine. Compression and oil analysis are fine. He is well respected
> around the local airport.
>
> He proposes either a name brand $16,000 overhaul, or a less costly
> option where he and a local aviation mechanic professor can work on it
> together ("two eyes are better than one" he says).
>
> If it makes a difference, I don't live in farmland. I live in the
> forest, with forest and lake for 100 miles in every direction.
>
> Any advise? Any way to explain to the wife? Anyone want a nice C-150
> with a new paint job but a tired engine?

Others have chimed in suggesting replacing only the top end components
that are out of whack. Consider that 27 years is more than TWICE the
manufacturer's recommended time to overhaul limit of 12 years. You may
get away with patchwork as others have claimed. But these folks rarely
report back when their high year, avoided overhaul ended them up in the
weeds. So, nobody has any real stats on how this crap shoot plays out.
Only the winners pipe up. It sucks but this is a reality with owning.
I'm not sure whether folks realize when they buy an airplane that
"judgment day" (the day when overhaul is necessary) must come. I figure
on a good chance of overhaul or at least some major engine work
(cylinder) when a plane is past 10 years or 1000 hours.

How to tell the wife? Explain the options. Patch it up and risk being
very dead in a crash, sell it and take a huge loss, or do it right and
have a safe plane to enjoy for the next 12 years. Divide $16k by 12.

By the way, don't just figure the price of the engine overhaul. You will
likely need an alternator and starter overhaul, new rubber mounts, new
oil and fuel hoses, new baffling, and lots of other small stuff. $5k is
a good estimate for planning (loan) purposes.

My only problem with field overhauls is that the finished product is of
unknown quality. It is somewhat of a crap shoot when the factorys/shops
do them. And those guys do it all day, every day. They know every little
nuance that can avoid later problems. And, you get a warranty. Yes, they
are very limited. But if the thing blows up 50 hours after you get it
back, they take care of the problem. With a field overhaul you are
likely out of luck.

Others likely have strong opinions contrary to mine. In the end, it is
your butt vs. your money at risk.

Good Luck,
Mike

[Orval Fairbairn[_2_]]

In article >,
Mike Spera > wrote:

> Charles Talleyrand wrote:
>
> > My local mechanic says that I need to overhaul my engine. It's got
> > 1200 hours but it's been 27 years since the last overhaul. He's
> > worried about the age, and he hears "piston slap" when he runs the
> > engine. Compression and oil analysis are fine. He is well respected
> > around the local airport.
> >
> > He proposes either a name brand $16,000 overhaul, or a less costly
> > option where he and a local aviation mechanic professor can work on it
> > together ("two eyes are better than one" he says).
> >
> > If it makes a difference, I don't live in farmland. I live in the
> > forest, with forest and lake for 100 miles in every direction.
> >
> > Any advise? Any way to explain to the wife? Anyone want a nice C-150
> > with a new paint job but a tired engine?
>
> Others have chimed in suggesting replacing only the top end components
> that are out of whack. Consider that 27 years is more than TWICE the
> manufacturer's recommended time to overhaul limit of 12 years. You may
> get away with patchwork as others have claimed. But these folks rarely
> report back when their high year, avoided overhaul ended them up in the
> weeds. So, nobody has any real stats on how this crap shoot plays out.
> Only the winners pipe up. It sucks but this is a reality with owning.
> I'm not sure whether folks realize when they buy an airplane that
> "judgment day" (the day when overhaul is necessary) must come. I figure
> on a good chance of overhaul or at least some major engine work
> (cylinder) when a plane is past 10 years or 1000 hours.
>
> How to tell the wife? Explain the options. Patch it up and risk being
> very dead in a crash, sell it and take a huge loss, or do it right and
> have a safe plane to enjoy for the next 12 years. Divide $16k by 12.
>
> By the way, don't just figure the price of the engine overhaul. You will
> likely need an alternator and starter overhaul, new rubber mounts, new
> oil and fuel hoses, new baffling, and lots of other small stuff. $5k is
> a good estimate for planning (loan) purposes.
>
> My only problem with field overhauls is that the finished product is of
> unknown quality. It is somewhat of a crap shoot when the factorys/shops
> do them. And those guys do it all day, every day. They know every little
> nuance that can avoid later problems. And, you get a warranty. Yes, they
> are very limited. But if the thing blows up 50 hours after you get it
> back, they take care of the problem. With a field overhaul you are
> likely out of luck.
>
> Others likely have strong opinions contrary to mine. In the end, it is
> your butt vs. your money at risk.
>
> Good Luck,
> Mike

Mike,

You did not specify whether it is a Continental or a Lycoming -- big
difference!

Lycomings, with the cam mounted above the crankshaft, have a tendency to
get corrosion on the front lobes of the cam, when the oil dries up and
moisture collects at the top of the crankcase. Usually it is the front
lobes that take the hit.

Continentals, with the cam below the crank, apparently manage to stay
covered with oil and avoid the corrosion problem.

Sometimes the valve guides get coked up and need reaming.

If all operational parameters look good, don't touch it -- just fly it.

All engines have some piston slap, due to the loose tolerances of
aircooled engines.

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