Engine question

[steve from staten island]

My buddy got a 350 GM engine from a guy who claimed it spun a bearing. It was just recently rebuilt and there were some good parts on it. When we disassembled the motor which again had very low milage the two front mains bearings were wiped out of babbitt. One of the front rod bearings had spun and really did damage to the crank, i think it was ruined. The bearing spun and was gone. The opposite rod journal was isn't looking to good either. So my question is what causes a bearing to spin and is it possible that babbitt material ruined those other bearings.

 

[PP1RT]

Too tight. Too loose. Improper lube. Improper assembly. Vibration....

 

[bm02tj]

Rod bolt hit crank took out rod bearing then starved mains of oil
Poor workmanship

 

[tomlin]

My buddy got a 350 GM engine from a guy who claimed it spun a bearing. It was just recently rebuilt and there were some good parts on it. When we disassembled the motor which again had very low milage the two front mains bearings were wiped out of babbitt. One of the front rod bearings had spun and really did damage to the crank, i think it was ruined. The bearing spun and was gone. The opposite rod journal was isn't looking to good either. So my question is what causes a bearing to spin and is it possible that babbitt material ruined those other bearings.

 

[tomlin]

Worked on a lot of small block Chebbies through the years. Usually front main/rod damage is caused from lack of lubrication. Probably didn't prime the oil pump before start up or they ran him out of oil. I have also seen the oil pump sump fall off and cause this issue.

 

[snakeoil24]

another big issue not enough crush when bearing was seated with main cap.