After only 200 mile the main bearing are down to the brass.I think my machine shop made a mistake, they polish the crank and said I needed under size bearing. The crank was not tight in the block when I put it in, but the oil pressure was very high(70-80 psi) when I started the motor up.200 miles later and the oil light came on and the motor had a knock.The under size bearing were installed on the mains and rods. The rod bearings look fine.Anyone have a theory as to what happen?
If they are down to copper I can almost guarantee it had nothing to do with clearance.
In the majority of cases this is dirt plain & simple
A picture would be nice
Now if they were burnt this is a different story.
What was used to clean the block?
Did you check all oil passages?
Clean the crank passages?
Did you get any where near the engine with one of those cute little abrasive discs like the 3m ones?
I have redone a few engines for repair shops that have just changed intake gaskets & used these things & of course "didn't get anything into the engine as they had rags in the lifter valley"
Took out every bearing in the engine within a couple of hundred miles,,