Hydrolock

Hydrolock (hydrostatic lock) occurs when liquid, usually water, enters a cylinder in a larger volume than the combustion chamber can hold. Because liquid does not compress, the piston cannot complete its stroke. The engine stops abruptly, and the force can bend a connecting rod or damage the crankshaft.

On motorcycles, ATVs and jet skis it typically happens during deep water crossings when the air intake goes under water, or when the bike falls over in water. A leaking fuel tap or float valve can also flood a cylinder with fuel.

If the engine stalls in water, do not try to restart it. Remove the spark plug, dry the air filter, turn the engine over to expel water, change contaminated oil and only then restart.