A spun bearing occurs when one of the bearings in the engine physically turns within its holder. Spun bearings are due to oil loss in the engine. There are several problems that can cause a new or rebuilt engine to turn one of the bearings. If your engine has spun a bearing, the entire engine will have to come apart to be repaired, and the crankshaft may have to be turned.
A worn out or non-functioning oil pump will not deliver enough oil to the crank case and cause the engine to become starved for oil. Oil starvation will cause the bearings not to receive the proper amount of lubrication. A lack of oil and lubrication can lead to warping and other deforming of key engine components, including the bearings.
There is a screen in the oil pump that keeps contamination in the oil from flowing through the pump and entering the engine. In the event that the oil pump pickup screen becomes clogged or blocked by a large obstruction, it can restrict the flow of oil, causing oil starvation which is one of the primary causes of spun bearings.
Oil is supposed to stay in the crankcase on your engine to keep it properly lubricated. Leaking gaskets or seals can cause your engine to lose oil and lead to a low oil condition in the crankcase. If there is not enough oil in the crankcase to keep the engine lubricated, the bearings can turn or spin.
