The main and connecting rod bearings should always be renewed during major overhauls and new ones used but old bearings are useful as an indication of the current state of the engine. It is common to find bearing failure caused by lack of enough lubrication, existence of dirt or other foreign particles, overloading of the engine and corrosion among others; all of which must be corrected before the bearing is put back for reuse. In considering bearings it is necessary to take bearings out from the participating engine parts and align them in sequence to be able to detect problems pertaining to crankshaft journal. Contaminants can find their way into the engine in many ways such as during assembly, in the filters and during machining activities and these penetrate the bearing material or cause scoring and gouging. If not kept clean and well maintained, symptoms such as loss of power, rough idle, and stalling are bound to appear, hence, proper cleaning of every part, as well as regular oil and filter changes should be observed. Without lubrication, problems such as excessive heating, overloading, oil leakage or blocked passages will cause severe harm and overheating. Other driving characteristics are also observed to affect bearing life; for instance, low speed, full throttle, will result to high loads that pushes out oil, short trips causes corrosion because of lack of enough heat. Moreover, bearings can also fail due to oil starvation and trapped debris or due to lack of clearance, which is also attributable to wrong ways of installation of bearings.