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Marks on wrist pin

No that is not normal but it doesn't look bad. I would suspect that the rod bushings weren't honed to the right size and/or no assembly lube was used. I would polish the wrist pin on a lathe with a piece of fine scotchbrite, and would pull the rod out and have it re-bushed. New rod bolts and nuts would have to go in.
 
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Any other explanations?

The rebuild was done by Penn Yan Aero so I have a high confidence it was originally done correctly. Any other takers? Pulling all the pins and rods is expensive if not warranted.
 
OH Manual

Take a look in the overhaul manual and see what the limits are.
 
Those parts look just fine. The "ring" on the wrist pin is the space between the piston and rod, the section where neither pin nor piston touch.

And the bushing probably wasn't honed properly, but the pin doesn't appear stressed by it so I'd leave it alone.
 
I hate to be the fly in the ointment, but something seems peculiar. An engine that needs a new camshaft 150 hrs after a major overhaul? Hmm. How does one replace a cam without removing all the barrels and splitting the case? If the case was split, the rebuilder then re-installed the wrist pin in that condition? Hmmm.
The first airplane I built had a suspicious engine, it REALLY took a lot of pleasure away from flying it. I suggest you have your favorite engine shop do a complete inspection. Yes, it will be expensive, but you will be thankful in the end.
 
Split case

I was told by my A&P instructor that it was not uncommon to simply slip the wrist pins in a low hr engine so the case could be split without having to purchase then re-seat new rings. As for the re-ground/installed cam. My guess was lack of flying hrs caused corrosion. When I had the jug off I ran an inspection camera all around the interior of the case and couldn't find anything out of place. If fact all the interior parts seemed to still have a good coat of preservative on them. Amazing for the time this engine was on the shelf!
 
Uneven Contact Pattern - odd

First, I am no expert on this engine type, but having been in 1000's of other engines, 2 things.

Like rocket bob, probably not "bad" but agree very suspicious. The wrist pin surface finish looks quite rough for 150 hrs, likely assembled that way, and the bushing has highly polished wear lines, not a more even wear pattern that is expected. So - - like others, recommend checking those bushings and ensure that the rod ends are within specification for concentricity before installing new bushings and reaming.

My 2 cents, not a final absolute judgement.
 
When you see patterns on bearing surfaces like whats pictured on the small end of the rod, that means the clearance is too tight. Since the clearance is too tight not enough oil is passing around the wrist pin and so what's there is getting so hot it burns and leaves a deposit.
 
Rod end more of a problem?

rocketbob said:
When you see patterns on bearing surfaces like whats pictured on the small end of the rod, that means the clearance is too tight. Since the clearance is too tight not enough oil is passing around the wrist pin and so what's there is getting so hot it burns and leaves a deposit.
Click to expand...
Are you saying that reaming the rod bushing and polishing the wrist pins may be an option? (If they fall withing tolerance). That could be done with the right tools and new cylinder gaskets. Much less invasive than removing the piston rods. What I am coming away with is this most likely isn't a problem but for an added margin of safety, polish the wrist pins and ream the bushings if they are undersized.
 
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You can't hone a rod bushing without a rod honing machine. Everything has to be perfectly square. But you can clean up the bushing carefully with scotchbrite and check the fit of the pin.
 
Bob's site

Yea,
I gave the photo to Bob as well and the OK to use it if he wished. Jury is still out on burnt oil vs out of round.

JD
 
Now flying

OK, after 20hrs I cut open the filter and found a bit of metal.

IMG_20140401_192427037_zpsf67590bd.jpg


What is really hard to see without a video is what I can only describe as aluminum powder or 'sparkly silt'
Besides that there were a few larger shavings

0ddeca57-34ce-4d86-a193-48efd2b9bd60_zps1d656582.jpg


Blackstone has done a few test and outside corrosion (going lower on each sample) there are no warnings about the metal.

Reading Skyranch, looking at the wrist pins (top of thread) and seeing this metal silt, I am now concerned about the wrist pin plugs.
Does anyone here have experience with the wearing wrist pin plug issues of the past? Suggestions on what to look for?
Right now I am leaning towards flying and monitoring it every 10-15 hrs.
 
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