Yanmar Bearing Failure

[Tanner17]

Anyone ever seen a crank bearing do this?

My L100-EE started to sound like the crankcase was full of gravel. I wanted to cry when I removed the oil filter and found it full of bearing material.

[thundercougarfalconbird]

i have seen lots of failed bearing that look like that, there are a few things that will cause it,

-was your engine new or used?
- what condition are the rest of the parts in the engine like?
- do you use a cvt?

-too much thrust load on on a ball bearing not an angular contact bearing (cvt's cause excesive thrust load back and forth as the belt shifts the action is not perfectly linear)

-previously damaged bearing befor install, or damaged during install (ie using a hammer or pressing the outter race when installing on to crankshaft, anything that will press the balls into either race causing dents)

-poor grounding through your engine or frame, and voltage being run through the crank and grounding on the balls to the block, something to check

-rust, was the engine sitting along time in storage?

- or just a garbage bearing from the factory

[Tanner17]

Thanks for the reply. The engine was used. I removed it from a non functioning gen set. It is a 2004 model but I believe it sat for about two years prior to my purchase. No rust and the rest of the internal parts look good. The balance shaft bearing on the flywheel side seems tight but that could be from the pieces of the crank bearing.

Im using this as a research engine on a dynamometer so no CVT. Just a driveshaft connected to a belt reduction then to a DC absorbing motor. The belt reduction has its own jack shaft and absorbs all the thrust so I dont think that is the issue.

I am hoping it was either a bad bearing or the bearing was previously damaged. I cant afford another failure.