ok my car had a knock so i replace the rod bearing last weekend.the last bearing on the crank did spin but didnt do major damage to the crank also didnt have any metal shavings.so i insert grease before i put the new rod bearing in place.got everything back together.i crank it up no knock at all,then after 15 min running time the knock come back slowly.

 

Don't bet on it.What does that mean?

It works like this. Damage: yes/no. Either it was damaged, AT ALL, or it wasn't, AT ALL. "No major damage" is about like "just a little bit pregnant": either you are or you aren't. Period.

Either there actually WERE metal shavings left in the motor, as there virtually ALWAYS are when a bearing trashes itself; and/or the crank was damaged. Either of those things will guarantee an immediate failure of a new bearing shell.

Sorry to be the bearer of bad news, but it sounds like you just wasted some time and gaskets and fluids.

 

the very last crank journal had light scars in it.and yes there was probably metal shaving still in there.

but what gets me after the grease i put on the rods bearing burn off that when it starting knock again.if the crank journal where worn down it would have started knock when it first crank it right?