Improper maintenance of the lubrication system is also the primary cause of reduced main bearing life.
A malfunction of the crankshaft/main bearing will usually be detected by reduced lubricating oil pressure. As with
rod bearings, continued operation with low lubricating oil pressure will lead to a rapid deterioration of the bearings
and eventually will produce a knocking sound.
A main bearing will be heard when the engine is loaded.
A damaged, worn or missing thrust bearing flange of the upper main bearing shell can be detected by measuring
the end play of the crankshaft.
Failures of driven units at the front or rear of the engine which increase the end loading can damage the thrust
bearing.
