O300D Aluminum in Oil

Gary Wilcox wrote:

When I bought the plane the pre-buy inspection was a complete annual and the
mechanic didn't mention any "aluminum in the oil" so apparrantly this just
started.

If the previous owner changed the oil and filter just before your pre-purchase, there
wouldn't be any particles in the filter for your A&P to find. Check the engine log
book. Assuming that an oil change was made and that the change was properly logged,
you'll know whether it just started or not.

What is the likely source of this aluminum?

Don't know that one. Most of the critical components such as bearings, cylinder
sleeves, wrist pins, etc. are not aluminum. I'd say that's encouraging. If I had to
guess, I'd say that a bearing is loose and eating away at it's housing, but that
usually makes a good deal of noise.

The mechanic suggested that I
fly for 10 hours and change the oil again to see if the problem goes away.

Stay close to home.

George Patterson
If a man gets into a fight 3,000 miles away from home, he *had* to have
been looking for it.

What is the likely source of this aluminum?

The O-540 in our Pathfinder was making metal at the pre-buy inspection. It
turned out to be aluminum from the piston pin plugs, and the amounts we
found convinced us to slash our purchase offer, and put in a new engine when
it was accepted.

(BTW: The new piston plugs are made of a harder alloy that won't spall,
supposedly.)

If you found a "few slivers" that's not abnormal. If there are a lot of
slivers, and you're flying a C-172 with the H2AD engine, you may have some
serious trouble brewing. (That engine was known for making metal, although
the latest oil additives supposedly have alleviated this problem.)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

How many years has it been since the engine was overhauled?

They hate sitting around.

Karl

A possible guess based on experience from a C-150 which has the same
cylinders -
It could be a wrist pin end plug scrubbing the cylinder wall. This
was caused by a loose (i. e. floating) wrist pin rod bushing. A C-150
of ours always had produced a very small amount of aluminum which our
mechanic condemmed as having a lemon engine.

On teardown we found one wrist pin bushing loose in the rod end, &
that mechanical rectification was causing the wrist pin end to scrubb
slightly on the cylinder wall. I suspect the bushing had been cracked
loose during a previous disassembly.

We redid it with Millenium cylinders & a new rod of course. It has
been good ever since. It now is again at or beyond TBO.