As the engine's overhaul proceed, although new main and connecting rod bearings are often fitted, it is informative to retain several of the old bearings for analysis. Failure to bear causes can occur from lack of oil or lack of clean oil, dirt or foreign particle, overloading of the engine, and corrosion among others must be checked before assembling again so that they might not be repeated. Regarding bearings, they have to be taken out from their s Mining th My location and spread neatly so as to match any defects with the crankshaft journal. It concerns foreign particles that can get inside the engine during its assembly, in the course of filter usage, or due to some machineries; these foreign particles may lodge themselves in the bearing material resulting to scoring or gouging. To avoid such failures, all parts must be cleaned and the oil as well as the filter changed frequently. The causes of lubrication breakdown are high temperatures, overloading, oil leakage, or blocked oil ways leading to adhesion of bearing material and hence high temperatures. Driving habits also affect bearings; for example, low speed combined with high gear results in high load, short trips expose them to moisture and gases resulting in corrosion. Some of the issues include tight bearing pocket or improper housing layout, trapped material between the bearings or housing halves and other such conditions. If original bearings are worn or if oil clearances are incorrect, new bearings must be obtained, especially if the crankshaft has been reground, as undersize bearings depending of the amount of material taken off would have to be used. The bearings for the automotive machine shop are available in standard sizes which has standard grinder in steps of 0.010 inch, and bluing done on the reground crankshafts show the amount done. Finally, oil clearance should be confirmed with the help of the Plastigage if there are doubts and it is always wiser to consult a machine shop or the parts department in the event of a doubt concerning the choice of bearings.