What Causes the Engine Flywheel to Fail to Rotate?

[SanElena]

There are several reasons why an engine's flywheel may fail to rotate: Excessive Tightness Between Bearing Bush and Journal: This is usually caused by new bearing bushes not being properly scraped, misalignment of upper and lower bearing shells, excessive installation height of bearing shells, incorrect placement of shims behind the bearing shells, or over-tightening of connecting rod bolts or main bearing cap bolts, leading to deformation of the bearing shells and localized seizure with the crankshaft journal. Compression of the Balance Shaft: In single-cylinder diesel engines, missing or improperly installed gaskets between the oil pump and the engine block can cause the oil pump shaft to compress the balance shaft below when the pump body bolts are tightened. Excessively Thin Gasket: In single-cylinder diesel engines, an overly thin gasket between the engine and the block can result in severe friction between the starting shaft shoulder and the gear housing cover. Defective Parts: Misalignment of the journal or the holes in the engine block's bearing seats, or interference between the small end of the connecting rod and the piston.