# 6 lower main bearing failure

[JTeague]

Hi guys. Sorry it took so long for me to answer your questions. The truck does get used for hauling. It is a Hot Shot rig with a 5th wheel plate that hauls a 40+ ft tandem dual flatbed. The truck did have a Fram filter on it when I tore it down. It was the revised filter with the A suffix. Oil type is unknown at this point. I will ask the owner next week when I see him. The thrust bearings were fine and no wear on the crank. The truck had 60 psi of oil pressure all of the time. Also the truck is equipped with a VA box. I still haven't found a good explanation for the problem except that the plating was defective on the bearing. I am going to sleeve the block back to std. replace the bad piston and ring only the bad cyl. I can't talk the owner into replacing all of the rings, which is totally stupid in my eyes. His truck, his money.

 

[B.G. Smith]

Opinion

Opinions are like elbows, everyone has one (or two). I would guess that the flaked bearing was caused by hammering. I would also guess that the cylinder galling happened first which caused the hammering of the main bearing. One more guess, the bearing on #6 probably had a little more clearance than the adjacent bearings causing it to fail from the hammering. bg