Assuming for a minute that the oil analysis and the oil on #1 plug are
not related, Blackstone could be right and it could be another cylinder
that has the broken pin plug. Can't that scraping be found with a
bore-scope like you did on #1? You shouldn't have to pull the cylinders
for that check should you?

If none of the cylinders show evidence of scraping, then the steel has
to be coming from somewhere else doesn't it?

This is very interesting...


-----Original Message-----
From: Robert M. Gary ]
Posted At: Wednesday, May 23, 2007 10:09 AM
Posted To: rec.aviation.owning
Conversation: Oil in cylinder, other cylinder issues
Subject: Oil in cylinder, other cylinder issues

I have a mid time (1000 SFNEW) IO-360 Lycoming engine.
Recently oil consumption has increased from about 1 quart/10 hours to
about 1 quart/ 5 hours. For a long time we've collected oil on the
bottom #1 plug but it seems like its worse now.

In addition, we've had high aluminum levels in our oil samples for
several years but now showing high iron and other harder metals.
Blackstone is saying that our oil sample indicates high blow by and
seems to show that a piston pin plug is now rubbing on the cylinder.

The oil filter is still showing only a small amount of metal. The IA
at the A&P school says the amount of metal in the filter is expected
for any midtime engine, not excessive. Since the last couple of
Blackstone reports have indicated the pin plug may now be rubbing on a
cylinder we've been doing a boroscope every 10-20 hours of flight.
However, the boroscope is still coming up with nothing (we have
Nitrite cylinders and the cross hatching still looks great).
Compressions were all very high (enough that the A&P is always a bit
suprised to see them so high all around for a midtime engine)

So, I'm wondering where I should go from here.

1) How can I tell if the oil from #1 is coming past the valves or the
rings?
2) Is there any reason to believe the oil in #1 cylinder and the oil
analysis issues are related?
3) Other than the oil usage in #1 I really have nothing to suggest one
cylinder over the other for making metal in the oil sample. Should I
just address the oil in the #1 cylinder and ignore the sample report
until there are other signs (filter, boroscope, etc)? Or, should I
just start pulling all cylinders (I'm told its about 10 hours of labor
per cylinder ) until I find a busted pin plug?
4) I spoke with Lycoming. Although they didn't have any suggestions on
how to determine which cylinder has the bad pin plug, they did mention
that if we find the issue before there is much scraping on the
cylinder we should be able to simply put the cylinder back on (and
avoid sending it to a cylinder shop, saving lots of $$$). So basically
the sooner I find this, the less expensive it will be (well, I guess
if I have to pull 4 cylinders before I find it, it might not be less
expensive).
5) If I find a pin plug broken what should I do? Several A&Ps have
told me that pin plugs just work loose on Lycoming engines and I
should just replace the busted one and forget it. Others have said I
should do something to the engine to prevent the next plug from
working loose (not sure what).

-Robert