Interesting that all 3 above contain aluminium.
There was also the Superior replacement.
However, it seems clear that the dome surface of the plug cannot possibly produce a nice even wide scrape on the cylinder wall. The culprit is probably a piece of deposit which came off.
A belated explanation: Lycoming had three different designs of piston pin plugs, made of two different materials:
For details, see SI 1267D.
2nd aluminium spike, after a sample with no aluminium elevation
However, borescope images show a chunk of crap having come off the piston crown right at that spot so that may be it
I am told my plugs were brass.
I dodged an expensive Lyco AD by the engine shop using Superior parts.
Thanks for reminder about aluminum piston pin plugs in Lycomings, I’d forgotten. I’ve spent a lot more time working on engines with snap rings or circlips and no plugs.
Peter wrote:
the plug is aluminium
So do I. At least on engines I worked on, all were aluminum. But I’ve seen some made out of brass as well.
As for the pin working directly against the cylinder wall, that would be a totally worn plug. Or one, or both, plugs not installed when the cylinder was installed.
I think the plug is aluminium. The small end pin is of course steel.
I will ask the engine shop.
A rubbing piston pin would leave a mark on the cylinder wall but it’s interesting to ponder how it might leave elevated aluminum levels in the oil, given that both pin and cylinder wall are steel. Perhaps the pieces of the piston?
W80 and Camguard.
Camguard uses calcium as a marker. I have this from its developer, Ed Kollin.
I have a borescope but I don’t know what that might show to point to the increased aluminium. I guess a rubbing piston plug may leave a mark on the cylinder wall?
@Peter – what kind of oil do you use? I assume you don’t use camguard since your phosphorous numbers are so low. Do you have a borescope? If so, you might get some clues there, as Dan did.
Here is my most recent report on my Lyco-clone IO-360 – I’ve got a sample in the mail now, but it has not yet arrived to Blackstone.
