Insufficient Lubrication From A Dry Start ::

A dry start of an engine after overhauling, without activating the oil pump leads to wiping out of electroplated layer and seizure of engine.

Oil Starvation ::

Insufficient oil supply due to malfunction of oil pump, blocked oil filters or any leakages, results into wiping out of the bearing alloy, torn lining and shifting of lining material towards the bearing edges.

Filed Parting Faces ::

When a bearing cap is given a specified torque, the parted faces mate each other in the bearing housing, known as ‘crush’. At times, the mechanic files these faces being under impression of achieving a better fit. On removal of the crush, the circumferential pressure is not developed, calling loose fitment of bearings. This stops heat transfer between the bearing and the bearing seat and tends the bearing towards the shaft, resulting in metal to metal contact.

Distress In Crown ::

Bearings can fail from fatigue, especially at crown, due to excessive idling. At lower idling speed, lubricating system becomes less efficient due to slow shaft speed, resulting in insufficient oil supply, leading to break down and cavitation of lining at crown.

Bearing Lining Corrosion ::

Higher water content or certain additives of oil and higher frequency of oil change can lead to corrosion. This causes rough and porous running surface with removal of overlay.

Fatigue Of The Electroplated Layer ::

Localized overloading at high operating temperatures can cause fatigue of electroplated layer and small hair line cracks are formed on the overlay of the bearing.

Fatigue Of Lining Material ::

Fluctuating heavy overloads and running of bearings beyond normal life span can cause fatigue of lining material. Fine cracks develop initially, which extends to bond line causing flake out of lining material.