When does an engine needs an overhaul?

[Victor]

When does an engine needs an overhaul? There are several indications
that the engine is comming to the end of its life. But what do peolple
really look for to decide an engine is to go to overhaul.

Low oil pressure, High oil temperature, Low cylinder compression, Loss
of power. Which is the factor that maters most. For example low
cylinder compression can easily be fixed replacing the cylinder not
necessarilly an overhaul.

Of course I am talking about part 91 operation. I have heard people
that run engines 1000 hrs and far more than ten years past TBO.

For those of you who decided to overhaul your engine. What made you
spend the big buck?

[Bob Noel]

In article >,
(Victor) wrote:

> For those of you who decided to overhaul your engine. What made you
> spend the big buck?

My decision is probably an outlier...

The engine only had 650 SMOH, but 14 years since overhaul.
3 of the 4 cylinders had cracked (chromed cylinders with
unknown number of hours on each). The oil pump AD was
due. And I was looking for an excuse to convert to 160hp.
In the process of the doing the overhaul, Penn Yan would replace
the flywheel for no extra charge (the aircraft used to have
air conditioning).

--
Bob Noel

[Aaron Coolidge]

Victor > wrote:
: When does an engine needs an overhaul? There are several indications
: that the engine is comming to the end of its life. But what do peolple
: really look for to decide an engine is to go to overhaul.

: Low oil pressure, High oil temperature, Low cylinder compression, Loss
: of power. Which is the factor that maters most. For example low
: cylinder compression can easily be fixed replacing the cylinder not
: necessarilly an overhaul.

Low power (low static RPM with a fixed-pitch prop), high oil consumption,
excessive camshaft wear (on lycoming engines), and the Lycoming oil
pump AD are popular reasons to overhaul. I think pilot comfort factor is
very important as well.

The Lyc. oil pump AD is what made my friend overhaul after 30 years and
3200 hours of operation of his O-320. Other wise it was running well.

Another friend had ignored the impulse coupling AD, and had the impulse
disintegrate and fill the oil with metal. Time for an overhaul!
--
Aaron Coolidge (N9376J)

[Craig]

"gpa" > wrote in message >...
> Thats an interesting question especially for the M14P radials that people
> are importing from eastern europe. Those engines I am told have a
> recommended "TBO" of 500-700 hours (depending on who you ask). But I
> understand what those countries do for an overhaul is not equivalent to what
> we do in this country. It's more of an inspect and replace if needed, I'm
> told. I heard that one of the importers of this engine ran one for 20,000+
> hours on the stand adding oil as needed. I would love to know if this is a
> true story and who did it and why they stopped the experiment (excess oil
> consumption, low compression, etc.)


20K+ hours continous would be a little over 28 months of 24 hours a
day. You would also be talking about over a quater million gallons
of fuel, at an average of $2 a gallon......for an engine that cost
less than $20K new.

You have to remember that Russian designs call for maintenance by
people that were essentially uneducated goat herders last week and are
now aircraft mechanics this week. They also design in great lattitude
in manufacturing tolerences because of this education and skill level
problems. Having worked on some of the most cutting edge aircraft from
the US as well as some of the best from MIG, it is understandable why
they do things the way they do. When the people from that region
manage to catch up with the west's level of normal education...look
out because they will possibly surpass us in building anything that is
mechanical.

Craig C.

[Steve Dold]

On 3 Aug 2003, Victor wrote:

> For those of you who decided to overhaul your engine. What made you
> spend the big buck?

My first overhaul was at about 1800 hours and the oil pressure was
low. It also used a lot of oil.


The second one was an O-200 that had 200 hours on it, On a routine oil
change I found aluminum in the oil screen from disintegrated piston pin
plugs. The screen collapsed and filled the bearings with oil, causing reduced running clearances.
This required complete dissasembly and repair. Luckily there wasn't much
wear to journals, cam, etc.

Once I did a top overhaul (replaced with Milleniums) because the blow-by
was causing overheating. It was using about one quart in four hours, but
the overheating was a problem, I was amazed how much difference it made,
the oil temps dropped over 30 degrees after the cylinder replacement.


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[Jay Honeck]

> For those of you who decided to overhaul your engine. What made you
> spend the big buck?

We discovered metal in the oil filter at the pre-buy inspection. This
forced us to lower our offer accordingly, and take the plunge on an
overhaul.

It was a giant pain in the butt, and very expensive -- but we haven't
regretted it. It's nice when the glass is still mostly full... ;)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Doug Campbell]

We had a first run IO-540 at 2400 hrs start to have a valve stick, and a
plug foul repeatedly.
Decided we had got our money's worth, and went overhaul rather than work on
the one cylinder.

We bought factory reman, so didn't get to find out the details of how many
things inside were near EOL.

After 2000 hrs, we had switched to more frequent oil changes (30 hr), with
analysis, to increase the warning before the end.

"Jay Honeck" > wrote in message
news:38uYa.88877$o%2.39014@sccrnsc02...
> > For those of you who decided to overhaul your engine. What made you
> > spend the big buck?
>
> We discovered metal in the oil filter at the pre-buy inspection. This
> forced us to lower our offer accordingly, and take the plunge on an
> overhaul.
>
> It was a giant pain in the butt, and very expensive -- but we haven't
> regretted it. It's nice when the glass is still mostly full... ;)
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Jim Weir]

The guy that taught me said that when you can read the serial numbers on the
metal chunks in the oil screen, it is time.

{;-)

Jim

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

[Mike Spera]

Our engine had 1830 hours and 18 years. It had been flown only 40 hours
for each of 2 of those years. Oil consumption was 1 quart in about 2.5
hours. Compressions were in the mid 60s and dropping. It was leaking oil
at the lower front case seal. The #1 cylinder had already been replaced
for an exhaust port crack. Replacement cylinder was an off-the-rack
chrome overhauled unit of unknown history. Baffle seals were eroding.
Oil/fuel hoses were antiques. Muffler needed overhaul. Carb heat shields
were deteriorating. Motor mount needed repainting. Carb accel pump seal
was just replaced for leakage. The oil pump gear AD was due. At that
time, the crankshaft corrosion AD was due and did not yet exempt the
150hp engine (which this was).

It was time.

Mike


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Mike Spera > wrote:


: Our engine had 1830 hours and 18 years. It had been flown only 40 hours
: for each of 2 of those years. Oil consumption was 1 quart in about 2.5
: hours. Compressions were in the mid 60s and dropping. It was leaking oil
: at the lower front case seal. The #1 cylinder had already been replaced
: for an exhaust port crack. Replacement cylinder was an off-the-rack
: chrome overhauled unit of unknown history. Baffle seals were eroding.
: Oil/fuel hoses were antiques. Muffler needed overhaul. Carb heat shields
: were deteriorating. Motor mount needed repainting. Carb accel pump seal
: was just replaced for leakage. The oil pump gear AD was due. At that
: time, the crankshaft corrosion AD was due and did not yet exempt the
: 150hp engine (which this was).

: It was time.

: Mike

Uh, yeah. I've got a buddy with a Cherokee 150 that just started
making metal in the screen. I'm thinking that it's time too. Probably
eating its cam, eh?



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