Just completed annual on PA-30B and found aluminum in the right engine oil filter.
Boroscoped the cylinders and found very slight....almost undetectable.....signs of wrist pin scuffing on the cylinder walls of #2 cyl.
Engine has 850 hrs. SMOH with all new Lycoming cylinder assemblies, all cyls. are 78/80 compression and oil consumption is 1 qt. every 20 hrs. with smooth operation and good looking plugs.
Any thoughts as to what causes a wrist pin to move out and abrade the cyl. wall and what do you do about it?
Steen Twinkie # N7997Y

Steve:

I have a '63 Comanche 250 with an O-540 engine in it. I bought my plane in 1991 and within a year my oil consumption went up from a qt every 4-5 hours to every 2 hours. I do my own oil changes and finally bought an oil filter cutter. When I opened it up I was really surprized. Aluminum all over the filter. Enough to cover about half the palm of your hand. When my mechanic looked at it we thought we had figured out the culprit cylinder. Turned out not to be the cylinder in question so we pulled them all. On the last cylinder we pulled the oil ring was broken in two place. More important was that the piston plug on that cylinder had wobbled a hole where it connets with the wrist pin. The hole located on the bottom of the connection point was about the size of a dime. The piston plug was just being eaten up. Ended up topping all the cylinder since I didn't have the money for a complete overhaul.

My advise would be to find the bad cylinder, pull it and see what you've got. If you can catch it early then youll most likely have to fix that one cylinder. Wait to long and it could get ugly. Imangine a hole in the side of your piston the size of a dime. As far as I know aluminum is only used on the piston plugs but don't quote me on that. I'd call Charlie Merlot and see what he thinks. Funny when I had my piston plug problem the engine ran just fine. Just thirsty for oil. Good Luck

Alan Cheak

Thanks, Alan.
I also always cut open the filters to see what might be there, but never expected to actually find anything!
I'm thinking the aluminum wrist pin button and you're saying aluminum piston material. Holy Cow!
My oil consumption is still very good but I think we will take a look at that #2 cylinder.
Any other helpful hints or thoughts on the matter out there?
Steen