Mar 02

Have you heard of “HYDROLOCK”?




Hydrolock (a shorthand notation for hydrostatic lock) is an abnormal condition of any device which is designed to compress a gas by mechanically restraining it; most commonly the reciprocating internal combustion engine, the case this article refers to unless otherwise noted. Hydrolock occurs when a volume of liquid greater than the volume of the cylinder at its minimum (end of the piston’s stroke) enters the cylinder. Since most common liquids are incompressible the piston cannot complete its travel; either the engine must stop rotating or a mechanical failure must occur.


Hydrolock most commonly occurs in automobiles when driving through floods, either where the water is above the level of the air intake or the vehicle’s speed is excessive, creating a tall bow wave. A vehicle fitted with a cold air intake mounted low on the vehicle will be especially vulnerable to hydrolocking when being driven through standing water or heavy precipitation. Engine coolant entering the cylinders through various means (such as a blown head gasket) is another common cause. Excessive fuel entering (flooding) one or more cylinders in liquid form due to or other abnormal operating conditions can also cause hydrolock.