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How to Avoid Hydrolocking an Engine

Looking through drops of water on wet glass to a rainy street

The inner workings of an engine depend on timing and precision — and also the laws of physics. When things go wrong, it may be a small problem that grows over time, or it could be swift with catastrophic damage. Hydrolocking an engine is generally the latter — if not catastrophic, then at least swift. Do you know what causes it? More importantly, do you know how to avoid it?

Under Pressure

Gas and diesel combustion engines rely on compression to get things rolling. Air and fuel enter the chamber and become compressed as the piston rises to create the perfect environment for combustion.

The piston can move because air is compressible, and when it’s put under pressure, it becomes denser and hotter. (Fluids can also compress depending on their density, but not enough to be part of the compression process.)

Aqua Man(agement)Car in puddle

If water enters an area where air is meant to be under compression, you’ve got problems. You can pressurize water, but your engine will have to answer for it.

When an engine hydrolocks, the pistons can’t compress fully — this will cause the engine to either immediately freeze if the car is idling or continue to move and quickly damage major components if enough force is behind it, like at higher speeds or with bigger engines.

Common victims of hydrolock are bent or broken connecting rods, crankshafts, cracked cylinder walls and blown seals and gaskets, to name just a few.

Jumping Through Puddles

Water can enter through the air intake valve, which often happens in floods or when driving through deep puddles. Coolant can also leak internally or excessive fuel can be dumped into a chamber.

The best way to avoid hydrolocking an engine is to remain aware and stay on top of engine maintenance and repairs. Don’t ignore small problems, and pay attention to your driving conditions. Stay out of deep water during storms, and watch out for air intake modifications that place your intake at a lower level than what was intended by the original design. When washing your engine, keep water away from the air filter, or remove it altogether and cover the intake opening.

Vigilance and maintenance are the two key players in avoiding hydrolock. If you suspect your engine has taken on water and will no longer turn over, take it to a mechanic immediately to avoid corrosion or further damage.

Check out all the engine parts available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on hydrolocking, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Pixabay.


Blair Lampe View All

Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter.  In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.

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