Showing metal at 1,100 hours

It does have mushroom lifters - my mechanic seemed to be very aware of
that fact but I didn't understand the ramifications.

wrote:
On Fri, 16 Dec 2005 23:24:45 GMT, Michelle P
wrote:


Maulesitter,
You do not need to pull a cylider to look at the cam.
Just pull the rocker arms, push rods, tubes and lifters. You can peer in
the hole with a flash light and mirrow.
Michelle


Unless it's one of the few Lycomings running around with
automotive-style barrel lifter bodies, the engine has mushroom lifter
bodies. The portion that rides on the cam lobe has a larger o.d. than
the rest of the body (and the corresponding hole in the crankcase).

TC

Ouch,
Sorry. Guess pulling a cylinder is in order.
Michelle

Maule Driver wrote:

It does have mushroom lifters - my mechanic seemed to be very aware
of that fact but I didn't understand the ramifications.

wrote:

On Fri, 16 Dec 2005 23:24:45 GMT, Michelle P
wrote:


Maulesitter,
You do not need to pull a cylider to look at the cam.
Just pull the rocker arms, push rods, tubes and lifters. You can
peer in the hole with a flash light and mirrow.
Michelle



Unless it's one of the few Lycomings running around with
automotive-style barrel lifter bodies, the engine has mushroom lifter
bodies. The portion that rides on the cam lobe has a larger o.d. than
the rest of the body (and the corresponding hole in the crankcase).

TC

As others have stated, you are free to pursue whatever path you like. On
one extreme, tear the engine apart and overhaul before further flight.
On the other side, fly for a few more hours, take another sample to the
lab, and cut open the filter to see if you have any more "goodies"
lurking. One course is known to be expensive up front. The other may be
just as expensive in the long run. If something major breaks in the air,
the outcome may be more expensive. No way to know until it happens.

It sat for 60 days prior to the bad oil analysis? Some say that could do
it while another camp says that ain't it. Really? Show me the testing
data either way. What we get out of the engine manufacturers and oil
companies suggest that anything other than almost daily flight of 1 hour
risks corrosion buildup at some rate. Seems to suggest that, under the
right conditions, you could be seeing 2 months of inactivity that ended
up in the oil sump. Then again, they sell oil and engines (and have
nervous lawyers and insurance companies). I don't expect them to say
"leave the engine idle for long periods and it will probably be O.K.".

I have seen a Lycoming 360 locally that ground a cam lobe to 1/2 its
original height. It ran fine and idled O.K. It made what felt to the
owner as full power. No way to know how long it was in that condition.
Some suggest that once the hardened layer is ground off a surface, it
will "go quickly". Have any of the engine manufacturers or oil companies
done any testing in this area to see how quickly this may happen?

There are those who say that flying further risks "more" damage. Well,
if you split the case at 1100 hours, you may want to strongly consider
a major anyway. So, other than an off-airport excursion, I'm not sure
what would be different in several hours as far as the overhaul. Maybe
some crank scuffing? As you said, if you pull a jug and see nothing,
then what? The only way to "know" you are O.K. in that case is a major.

The thing that irks me when I get in this situation (like a cylinder
that might be going South) is that I cannot FLY the thing anywhere with
confidence except a local hop. Until the problem is resolved, the plane
is "down" as far as I'm concerned. No freedom to take a 400 mile jaunt
whenever I want is as good as no plane at all. Worse, in fact. I have a
potential financial liability simmering on the ramp that I cannot use.

Good Luck,
Mike

On Fri, 16 Dec 2005 16:36:36 GMT, Maule Driver
wrote:

I've put over 1,000 of the 1,100 hours on this new O-360-C4f. Changed
the oil religiously. I didn't baby the engine but didn't abuse it
either. Always hangered etc.

My last oil analysis showed a doubling of iron 47.9ppm to 101.0ppm with
36 hours on the oil. Everything else normal. We did the filter and we
found very fine iron filings or dust with a magnet. How much - hard to
tell. No chunks though.

We're thinking cam and lifter.

snip

Thoughts?

Does the engine sit idle for extended periods of time?
Storage/operating climate?

Lycoming could analyze the filter contents, or you could use other
facilities.

http://www.championaerospace.com/oil_kit.html


http://www.avlab.com/

As Denny indicated, at mid-time, it would be advisable to make a
positive determination before possibly doing more damage.

Pulling a cylinder and getting it honed and new rings fitted (might
have the e-valve guide looked at while your at it) is pretty cheap
compared to an early overhaul. If you have access to a decent shop,
pulling a con rod and inspecting the bearing is also a good idea when
you suspect metal contamination.

TC

My call - (not an A&P but a mech engr). That it keeps producing metal
(really how much though) makes me wonder.

I can't imagine this to be simple cylinder corrosion products. It all
depends on what you find, but it sure sounds to me like a cam failure.
The next question is why, on a nearly new engine.

Maybe you could get by with just removing the four rocker box covers &
see if the valve travels are still equal using a dial indicator.

If they are equal travel, it could be an oil pump or other accessory
gear.

If they are not equal, that would suggest a good choice and location to
remove a cylinder & look at that cam lobe system. Two of the cam lobes
are doubled up so that they each drive two intake valves on opposite
sides of the engine. These might be the most likely cam lobes to
fail, with the failure probably initiating on the RH side if it is
cold-start related.

Another possibility is a scored cylinder. If it is from cold start
damage, it will probably be worse on the top right side of the engine.
You might be able to see this with a light thru the top spark plug hole
while looking thru the bottom hole. Do this in a dark area. Maybe
your mechanic has a borescope alternate.

Assuming this engine has a full flow filter (not just a screen), the
condition of a typical rod bearing could be determined after a cylinder
removal. If it has only a screen, the bearings will almost certainly
be contaminated.

If there is camshaft or lifter debris embedded in the con rod big end
journal, I'd want to stop any further operation in hopes of at least
saving the crankshaft from further damage. Any camshaft wear debris is
going to be very hard & just might have the potential of scratching the
nitrided crankshaft. If any cam lobe is worn down, it isn't going to
heal itself - it's just going to create more metal.

Let us know what you find.

nrp wrote:

The next question is why, on a nearly new engine.

I don't regard 1,100 hours as "nearly new."

George Patterson
Coffee is only a way of stealing time that should by rights belong to
your slightly older self.

Correction to my earlier post - Cold start cam failure on any dual
follower lobes will probably initiate on the LH side due to oil spray
patterns in the crankcase.

On the 1100 TT point by George P - I was thinking that the cam was at
least not a second run one, in which case it would be a premature
failure.

"Maule Driver" wrote in message
news
I want some second opinions. I could fly 10 more hours and take another
look. We could pull a cylinder and check the cam I'm told.

Or fly another 10 hours and wind up with a ruined engine and a much larger
bill. I would play it safe.

"Maule Driver" wrote in message
news
I've put over 1,000 of the 1,100 hours on this new O-360-C4f. Changed the
oil religiously. I didn't baby the engine but didn't abuse it either.
Always hangered etc.

My last oil analysis showed a doubling of iron 47.9ppm to 101.0ppm with 36
hours on the oil. Everything else normal. We did the filter and we found
very fine iron filings or dust with a magnet. How much - hard to tell.
No chunks though.

We're thinking cam and lifter.

My mechanic is playing it safe - called Signature and Mattituch who
recommended no more flying, split the case, and fix or overhaul.

I want some second opinions. I could fly 10 more hours and take another
look. We could pull a cylinder and check the cam I'm told.

I've read about Second OilPINION and Howard Felton - a knowledgeable
analysis of the metal seems like money well spent. Is he still in
business? Anyone know anyone else who can do this?

Any other factors? My exhaust manifold/heat exchanger broke and I flew
for 10 to 36 hours with it broken. Parts 'banging' around under the
cowling etc. Discovered it during oil change. I did let it sit without
running for 60+ days - a first for this aircraft.

Thoughts?

Maulesitter.

Since you let the aircraft sit for 60 days, is it possible (likely?) that
the metal you are seeing is simply the layer of rust that formed on your
cylinder bores?

KB

Kyle Boatright wrote:

Since you let the aircraft sit for 60 days, is it possible (likely?) that
the metal you are seeing is simply the layer of rust that formed on your
cylinder bores?

Possible? I certainly hope so. Likely? I don't know. Does anyone
doing regular oil analysis see this when their a/c sits idle for 60 days?

I realize that if I have a jug pulled and find nothing then I really
have a problem. What is it? Rust in the cylinder bores would be a
Christmas present.