Engine Hydrolock – How Water Can Damage or Destroy Your Engine

It is true that water is healthy and good for life, but not for an internal combustion engine. That's why when you see a ford or a big puddle in front of your car, think twice before splashing into that in an attempt to get more bonus points for an artistic impression. It might end up very badly.
Ram TRX Drowned 11 photos
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Internal combustion engines run on gasoline, CNG, LPG, or diesel. Some are using hydrogen, but those are very scarce. Their principle is quite simple: fuel and air get in, the mix is ignited, and pushes the pistons from the top dead center to the bottom dead center and thus producing torque. But what if water gets in? Will that work?

A short answer is no. If your car just sipped from a puddle, that's not good, but it's not catastrophic either. On the other hand, if it took a gallon, then it's a bye-bye engine. But first, you should find out how water can get inside a car's engine.

Every vehicle has an air intake. The engine needs that to breath-in, mix it with fuel, burn it, and spit the exhaust gases out. You already know that. To avoid a hydrolock situation, you need to find where the air intake is, since that might be found behind a headlight, at the bottom of the bumper, or near the radiator. That's for the vehicles with the engine at the front. Those with a mid- or rear-engine have air intakes either on the sides or on the upper side.

So, even if it might sound strange, you have more chances to kill your Bimmer in a poddle than the guy next to you with a Lamborghini. But rest assured; if the water is deep enough, both will drown anyway.

Rivian R1 T
Photo: Nuwan Rajapakse/YouTube

Hydrolock consequences

So, what exactly happens when water gets inside an engine? There are two scenarios here. If the amount of liquid is just enough to fit between the pistons at the top dead center and the cylinder heads, the engine will stop without significant damage. But when it is more than that, disaster will follow.

Since liquids cannot be compressed, the pistons will be stopped by the water. As a result, some major internal components of the engine will break. That's why it is not recommended to try and restart it in the middle of the puddle, with water wetting your floormats and, perhaps, your seat. Just turn off the ignition and call for help. It's already too late to handle things by yourself, and your car's engine is already in a hydrolock danger.

Generally, when an engine hydrolocks at speed, the force of the camshaft pushing bends the piston rods, which are folded under the piston above them. While the crankcase or the heads can be ruined in the process and the crankshaft bearings destroyed, the shock can even cause cracks in the engine block.

The solutions

Actually, using the starter motor with the aim of bringing the engine back to life is the most common way to solve the problem (if no damage has occurred), but only after the combustion chamber has been given an orifice to eliminate the water through – this can be done by removing the spark plugs or the injectors.

Bronco Water damage
Photo: Buckle Up Buttercup/Youtube
You'll notice the water being thrown out of the cylinders, and the engine should start as normal afterward. At a certain point, you can see a strange gas coming out of the exhaust, which is the result of the unusual mixture that was burned in the cylinders, but this problem should go away briefly.

Serious situations such as the ones described above (read: when the unit has been damaged) generally lead to problems so profound the engine needs to be replaced altogether, as trying to rebuild it after multiple major components have failed would only result in even greater costs.

How to avoid hydrolocking

If you encounter a wade, stop and check by foot or with a stick how deep it is. The biggest mistake would be to try and pass through with speed. Due to inertia, you might get on the other side, but don't forget that water is a terrible break. So check to see if the level of the water is above your car's air intake. If so, just turn around, and if it isn't, you might try your luck. But there are a few steps recommended. Open the car's windows, so you can jump out if things go south. Turn off the AC, so the ventilator's blades won't hit the radiator if they start while submerged.

Then go at a steady speed. The car's shape will form a wave in front of it. Stay behind, and you might be safe. As a rule of thumb, if you see the water on the hood, just stop at once. Don't wait to see it on your windshield because that might be too late. Last but certainly not least, don't rev up the engine. That will help water get inside the air intake.

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About the author: Andrei Tutu
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In his quest to bring you the most impressive automotive creations, Andrei relies on learning as a superpower. There's quite a bit of room in the garage that is this aficionado's heart, so factory-condition classics and widebody contraptions with turbos poking through the hood can peacefully coexist.
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