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What is a Hydrolocked Car and Why It’s Important to Learn About It

The first rain showers of November’s Northeast Monsoon Season have started to give Malaysians flashbacks to the dreaded Taman Sri Muda floods that happened last year. Even this year, that same area was struck with another flash flood too. Given that monsoon season is soon upon us, it pays to be prepared by understanding certain terms and care techniques for your car. 

Malaysian Automotive Association president Datuk Aishah Ahmad said that during and after flash floods, you should never attempt to start your vehicle if it has been caught in floodwaters, for a good reason. 

Amphibious vehicles are lesser prone to a hydrolocked carA common phrase people use when their car or engine gets submerged is “submerged or flooded engine”. While this may be a mere sample of everyday speech, the proper term used is hydrolocked. Unless you’re driving an amphibious vehicle like that submersible Lotus Esprit from that James Bond film, a hydrolocked car can cause serious damage to your engine if drivers do not know how to handle it.

What is a Hydrolocked Car?

Water and oil don't mix. This is how a hydrolocked car happens.Water and oil do not go well together, neither is water in your engine. Hydrolock is a shorthand notation of two words – hydrostatic lock or hydraulic lock. It is a phenomenon where reciprocating parts of the engine e.g. pistons are obstructed from moving after a certain amount of liquid has filled in the room where the moving pistons are supposed to be. When water has flooded the air chambers of the engine, fuel combustion is unable to happen. Engines need air to function. 

Damanged pistons in a hydrolocked carWhen the pistons do not have the space it requires to reciprocate, that’s when the engine suffers from mechanical failure. To make this easier to understand, take a small plastic syringe and block the end nozzle with your finger. Then, push down the plunger with your thumb. It should be able to push the air out easily. A working engine must be able to perform this in order to keep running at high RPMs. Now fill that syringe with water and push the plunger down again. Notice it’s harder to do so? Liquids are not easily compressible, unlike air.

This, however, does not mean that car engines should be running dry all the time. Our engine still requires a small amount of fluid lubrication in order for the parts to be running smoothly. A hydrolocked car can suffer from a catastrophic failure if it occurs during high revs. Notably, the connecting rod of the pistons, crankshaft, engine block, crankcase, and bearings, sometimes all at once. You’re going to need a new car. 

Read More: Dangers of Buying a Flood-Affected Car

How and Where Can You Get Yourself a Hydrolocked Car?

Driving through flooded regions are prone to hydrolocked carsHydrolocking, as mentioned above occurs during heavy floods or when a car finds itself driving too deep in watery areas. While our cars can withstand some depth, there are proper techniques to drive through flooded areas without having your engine hydrolocking. Other causes of hydrolocking can occur during heavy storms or driving too deep in mud puddles.

If you do have to drive through flooded areas, always keep your foot down on the gas and keep the vehicle in low gear. This ensures the exhaust keeps pushing out high-pressure air to prevent water from flooding the exhaust. That’s why trucks with modifications for offroading have a snorkel/exhaust system mounted on the top of the vehicle.


Read More: How to Drive Through Flooded Roads

How to Know If Your Engine is Hydrolocked?

The noise is going to sound expensive. Most notably:

  • The engine starts to stall
  • Abnormal sputtering from the engine
  • Loud, thumping noise when starting the engine. 
  • Knocking, hammering noise
  • Engine has no response at all

Can a Hydrolocked Engine Be Saved?

Fixing a hydrolocked carGood news. The answer is yes. Generally, hydrolocked engines can be saved, provided you do not start the engine after the flood waters subside. Attempting to start the car will further accelerate the damage to your engine! Even if you can get it started, the engine is going to sound rough due to one or more bent piston rods. Get your car towed and settle down at your garage or workshop. 

Read More: How To Spot a Flooded Car for Sale Before It’s Too Late!

Bonus: Fixing a Hydrolocked Engine

If you do attempt to fix your engine yourself, get your vehicle towed out into a safe area first. Replace the air filter, spark plugs, and a new battery before you start the car. Since the engine was partially submerged in water, it’s going to be like a water fountain for a short period when you give it a rev. Don’t be alarmed. This is perfectly normal as the engine is expelling all the water trapped in it. However, it’s best to take it to a mechanic if you’re not sure what you’re doing. 


We’re expecting the worst when this monsoon season arrives. We hope you may find this guide useful and learn something new today. Stay safe and take care of yourself out there.

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