This is from my 1999 jeep xj 4.0 … Can anyone explain the reason for this main bearing chewing its self up ? Is it the thrust bearing not being set correctly or something else. Also has this happened to anyone else before ? Thanks in advance

 

Is that the only bearing damaged, is it a new rebuild or original ,how was your oil pressure...what does the crank side look like. How old was the oil.

 

it was a new rebuild build and the crank wasn’t to bad alittle bit of scoring, however the oil was very slugged up when I tore it apart and the oil wasn’t that old maybe a thousand miles but it did sit for a while.

 

How does the side of the thrust bearing look? If it shows wear, then its something with your TQ converter. It either wasnt pushed all the way in to begin with or its ballooned.

 

There is a thrust bearing in the #2 position...correct? Is that the only bearing damaged . Did you plastigauge that bearing or any others.?

 

Only physical contamination can cause that. Someone forgot to clean out either the main oil galley or the crank itself.