When overhauling an engine, therefore it is recommended that the main and connecting rod bearings be replaced with new ones and that the old bearings be kept to as they reveal information about the state of the engine. The causes of bearing failure are many, such as lack of oil, dust, overloading of the engine, corrosion among others and all these should be checked before reassembling the engine in order to prevent a repeat incidence. When inspecting bearings they should be taken out from their location and lied aside to allow matching of any defects with the crank shaft journal. They might be trapped in the engine during assembly or through the filter or through the PCV system; some might be machining or reconditioning debris. Some of these foreign particles may be lodged or trapped within the bearing material and can severe scores or gouges if the particle is larger. To avoid such failure, all parts must be cleaned to the best of their ability as well as the oil and filter changes. Inadequate or insufficient lubrication can be caused by reasons such as heat, overloading, leakage of oil or blocked passages, which can lead to severe abrasion, where the bearing material is removed off the backing. Antecedent driving practices also contribute to bearing degradation; for example, full power in slow speeds churns out pressure that compels the oil to expand thus squeezing it, short trips on the other hand encourage corrosion owing to failure of generating adequate heat. Further, there can be wrong fitting of bearings which may outcome into oil deprivation or high point which leads to failures.