331 bearings

Jerry He · Apr 17, 2015

I have a Kubota 331 mower that has a diesel engine with 1200 hours on it. While using it I noticed it losing power and thought the fuel filters were bad. I slowed it down and it died, I tried to start it and it was trying to lock up. After it cooled it started and ran fine for a minute and then started to labor. I shut it down and put a mechanical gauge on the oil pressure . I restarted it and it had 50lbs of pressure. It started to labor and with the fill cap off of the valve cover it started to smoke as the oil was hot. we disassembled the engine and found all the main bearings destroyed. the rod bearings look fine. How could this happen that the mains are all trashed and the rod bearings are fine. We have many Kubota mowers and a lot more hours than this. I use all Kubota filters and change oil as it should be.

mkirsch · Apr 17, 2015

The more of any one thing you own, the more likely you are to run into a bad one. It doesn't matter how good of a reputation a brand has or how much QC they do, a bad one will slip through.

Sounds like maybe the mains were a little tight on the tolerances to me.

jm. · Apr 18, 2015

Kinda hard for the crank to not have oil at the mains and still have oil at the rods. I have seen it the other way around. Most of those engine are just about bullet proof less getting them hot and cracking a head. I sure would look hard at the block and those carriers that hold the crank. In my 28 years KUBOTA experience can,t really say I have had anything like this. What brand and weight oil were you using just for my information.?

Jerry He · Apr 19, 2015

I use FS 15w40 in it as do I in everything we own.

331 bearings

Jerry He

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mkirsch

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jm.

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Jerry He

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