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.

[GrantLynn]

When the car's flywheel won't turn, I've encountered similar situations which are usually caused by internal engine seizure. Piston rings getting stuck in the cylinder is one of the most common causes, often due to insufficient lubrication leading to excessive friction. Damaged crankshaft bearings can also prevent flywheel rotation, especially in high-mileage vehicles. When engine oil deteriorates or there's insufficient lubrication, components can't slide smoothly, thereby locking the flywheel. Additionally, if foreign objects like small screws fall into the engine cavity, they may jam rotating parts. It's recommended to immediately stop the vehicle to check oil level and listen for abnormal knocking sounds during startup, as these indicate potential failures. Avoid forced starting to prevent further damage to core engine components - it's best to contact a professional repair shop promptly for comprehensive diagnosis. Regular oil changes and using high-quality engine oil can effectively prevent such issues. Don't wait until minor problems escalate into major repairs.

[Sue]

Last time my car's flywheel got stuck was due to a crankshaft issue, which taught me a lesson. Neglecting regular oil maintenance in daily driving resulted in the lubricant becoming too thin to properly protect bearings and pistons, causing the flywheel to seize. Prolonged high-RPM engine operation also accelerates component wear, such as frequently driving overloaded uphill, where stress accumulation leads to crankshaft deformation. Another common factor is starter failure – although it's an external component, insufficient torque output prevents proper flywheel response. If this happens, don't panic: first verify sufficient battery voltage and normal oil pressure gauge readings, then check for coolant leaks or oil stains around the engine. Timely maintenance can save major repair costs.

[StHarper]

There are several possible reasons why the flywheel cannot rotate: the piston is stuck in the cylinder, possibly due to excessive carbon buildup or poor lubrication; the crankshaft bearing is damaged, causing excessive friction; lack of lubricating oil prevents the system from operating smoothly; the starter gear is damaged or improperly engaged; or the flywheel itself is deformed or the mounting screws are loose. These faults can all cause the engine to fail to start, so it's important to carefully identify the root cause and not overlook any details.