LO 8-11 Identify and describe the purpose, function, and types of diesel engine flywheels

Reinstalling a Flywheel Housing

A flywheel housing and engine crankshaft must share a common centerline to prevent flywheel runout between it and the transmission input shaft. This is a particularly important check that must be made whenever a flywheel housing is transferred from one engine block to another, such as during engine replacement. If the reinstalled housing centerline does not match the centerline of the crankshaft, even if alignment dowels are used, significant problems can develop. First, the rear main seal may leak. Second, on manual transmissions, the input shaft bearing and the seal will quickly fail because the input shaft is operating at an angle. Vibrations produced by the nonaligned input shaft will travel up the main shaft in direct gear and cause gear jump-out in a non-synchronized transmission. Clutch plate splines and the input shaft will wear rapidly. With automatic transmissions, the transmission input seal will also leak. The starter motor may even be excessively noisy.

To reinstall a flywheel housing, follow the guidelines in Skill Drill 8-1.