Explain bearing wear pattern

Long story but can be foundhere: http://www.kcjeepclub.org/forum/viewtopic.php?t=12960

short story... knock returned after rebuild... check flex plate tight and not cracked.

here is the #5 lower rod bearing where the knock is coming from...









i also plasti gauged at BDC and at 9 o clock and both were between .0015 and .002. desired clearance is .001 but allowable is .003

thanks for the help... im totally lost what could cause this and its my DD.. and ony vehicle... and there are only about 500 miles on this bearing

Is it wearing on # 5 only ? If so you need to inspect the # 5 crankshaft journal .

When you rebuilt the engine did you have the crank inspected and polished ? What cylinder was knocking before the rebuild ? If it was #5 before the rebulid , then the crank is grooved or you have a bent rod .

#3, 4, and 5 have similar wear patterns. the crank was not polished, but was not grooved. i dont know which one was knocking for sure... it wasnt consistent.

here are all of them in order with #1 at bottom and right

Hmm....did you ever have the head checked when you did the head gasket?? It may have been slightly warped.

I read some of your posts over on the other forum....I'd just grab a new motor!!!


I could take a guess and say that coolant leaked into the cylinders, which reaked havoc. It would explain the opposite wear patterns on the upper and lower journals.

I wouldn't throw any more money at this motor, just grab another one from a junkyard.