1. Seized Pistons or Piston Rings: If the engine has been overheated or has experienced severe oil starvation, the pistons or piston rings can seize within the cylinder bores, preventing the crankshaft from rotating.
2. Failed Rod or Main Bearings: Worn-out or damaged rod bearings or main bearings can seize and lock up the engine. This is often accompanied by knocking sounds before complete failure.
3. Broken Timing Belt or Chain: A snapped timing belt or chain can cause the valves to collide with the pistons, resulting in severe damage and preventing the engine from turning over.
4. Hydrolocked Engine: If water or other liquids enter the combustion chambers, it can cause the engine to lock up. Hydrolocking occurs when the incompressible liquid prevents the pistons from moving freely.
5. Catastrophic Internal Damage: In rare cases, catastrophic internal failures such as broken connecting rods, cracked pistons, or severe damage to the crankshaft can also cause the engine to seize.
6. Starter Failure: While not directly related to the engine itself, a faulty starter motor or solenoid can prevent the engine from cranking, giving the impression that the engine is locked up.
If your engine is completely locked up and won't start, it's important to have it inspected and diagnosed by a professional mechanic to determine the exact cause and extent of the damage. Depending on the severity of the issue, it may require extensive repairs or even engine replacement.
