Fail mode?

[tim2542]

Can anyone tell me the fail mode seen in this bearing? This is a friends 0-200A Continental, relatively low hours on field overhaul. The pic is the #2 bearing, #3 looks similar but better, #1 looks relatively normal with a little debris damage, nothing serious. The engine was disassembled looking for a low oil pressure issue. Pretty sure this is it, but this damage does not look like lack of oil pressure or debris damage. I?m only guessing but it looks like corrosion or some kind of plating failure. The tin babbit is all gone on this one, and much of the copper. The crank looks decent, probably will clean up with polish only. Information from the previous overhaul is sketchy, not even sure the bearings were replaced.

http://i1380.photobucket.com/albums/...sgwyt9spe.jpeg

[rackley16]

By the looks and the description I would check the case halves for alignment of the bearing bores. sounds like there is case distortion or the crank is bent. That bearing got hot.

Does your friend cut the oil filter open every oil change? Did he do it for a period of time after the field overhaul?

Anyway, I would ship the cases off and the crank to be checked and reworked.

[lr172]

Wish I could help, but never have seen one like that. Definately seems not to be caused by debris or contact with the crank. I can't imagine what would cause coppoer to break off like that. Copper doesn't really corrode agressively in this environment and I wouldn't expect heat damage to look like that. Copper is very effective in heat transfer and it would take a LOT of heat to break it down and I would expect smearing and deformation, not the pitting/breaking off shown here.

My best guess would be a defect in manufacturing of the bearing, but that is purely a guess. If you can't identify the cause, I am with the previous poster that a check of the crank and case is in order to be safe.

Larry

[longline]

inspect the bearing and determine the manufacturer. Options are Continental, Superior or Fresno Airparts. If this is what I think it is we can tell you exactly what happened.

[N941WR]

Which prop did he have on that engine?

There have been issues with the Sensenich Ground Adjustable Prop being so stiff that magnetos won't make 40 hours on the O-200.

[MarkW]

I am with Larry on this one.
Never seen it just wipe off the overlay like that without further damage.
Hopefully BillL will be along as this is his specialty.

[phdugdale]

Hello
I assume the crank was reground? I would check the surface finish on each journal, I suspect the damaged shells location are the roughest?....

[EXflyer]

Have seen bearings with that type of damage due to corrosion from moisture. As far as case problems, that can be told by main bearing wear. It will show up on one bearing half and not on the other or at the same point on both where they separate and 180 from that have none. that shows a warped case. They will run like that for hours with the original bearings in them but put new ones in and have seen a crank break on diesel truck engines. That is the first thing to look for when considering line boring a case or block.

[BillL]

Originally Posted by EXflyer

Have seen bearings with that type of damage due to corrosion from moisture. . . .

Agree . . My gut was corrosion, but moisture is right there. Sulfur in the fuel and blow-by will acidify the moisture in the oil. Another contributor is overdue oil changes and allowing TBN (ability to neutralize acids) to fall out of usefulness. The PbSn overlay is completely gone, (dissolved) this is possibly the worst bearing I have ever seen.

Confirmation would be how the remainder of the innards of the engine look. Cylinder walls, cam, and lifters.

[bret]

I have seen this in marine engines, high moisture content in oil along with acid build up, leaving contaminated oil in for a long time with engine stored.