The leading cause of engine bearing failure is ____________.

The leading cause of engine bearing failure is inadequate lubrication. Proper lubrication is essential for reducing friction between the moving parts of the engine. When there is insufficient oil flow or the oil is not distributed correctly, the bearings do not receive the necessary protection or cooling. This can lead to overheating, excessive wear, and eventually catastrophic failure of the bearing surfaces. Inadequate lubrication can result from several factors, such as oil pump failure, low oil levels, or a blockage in the oil passages.

While issues like contaminated lubricants, improper storage and handling, and installation errors can also contribute to bearing failure, inadequate lubrication is the most critical factor. Contamination can affect lubrication efficiency, but without adequate lubrication in the first place, bearings are much more likely to fail. Proper engine maintenance and monitoring of oil levels are crucial to preventing inadequate lubrication and ensuring the longevity of engine bearings.