What Is A Hydrolocked Engine And How Do You Fix It?

Do you know what a hydrolocked engine is? Here we will answer that question as well as talk you through what causes an engine to hydrolock, whether hydrolocking harms an engine, and how to fix a hydrolocked engine.

Aspiration is that coughing and choking feeling you get when food or liquid goes down “the wrong pipe.”

Something similar also occurs if too much water enters your engine, it’s called hydrolock, and it can cripple your car!

What is a Hydrolocked engine, and how do you fix it?

Engine pistons are designed to compress a mixture of air and fuel – not water. Because of this, if enough water enters the cylinder, it may hydro lock, meaning they all stop moving at once.

Much of the resulting damage depends on how fast you were going when it happened.

Thankfully, in this guide, we will explain everything you need to know about a hydrolocked engine. This also includes what prompts an engine to hydro lock, if it can cause damage, and how to fix it.

Are you ready to get started?

Let’s dive right in!

Table of ContentsShow

What Causes An Engine to Hydrolock?

driving in water
Do not drive through puddles as it may cause a hydrolocked engine.

The actual term is Hydrostatic Lock, which has been shortened to hydrolock. This happens when too much water enters the combustion chamber. When a piston reaches the top of its travel range, if the volume of water inside is more than the amount of space that’s left, hydrolock will occur.

Why? Because water is less compressible than the air/fuel mixture inside. So, when the piston attempts to compress it, all of the cylinders will stop at once.

This will result in crashing or knocking sounds inside the engine that will last several seconds, followed by it shutting down.

What kind of situation can result in water entering the cylinders? There are many examples, like driving in a downpour or going through a deep puddle. This is one of the reasons that flood-damaged vehicles are often totaled afterward.

It’s also possible for hydrolock to occur from other liquids, like oil or coolant. However, keep in mind that if this happens, it likely means you have a severe issue inside your engine, like a blown head gasket or a crack in the block.

Does Hydrolocking Harm An Engine?

car engine with hoses

Hydrolock can be very harmful to an engine and may require its replacement entirely. However, the speed you were going is what usually determines the extent of the damage.

While the RPMs are low, such as when you’re idling or moving at a slow speed, only a small amount of water may enter. In this case, you need to act swiftly to remove it before it causes corrosion issues.

If you were going fast when the hydrolock occurred, where the RPMs were high, severe damage might occur.

Some of these include:

  • A bent or broken connecting rod
  • A breach in the head
  • Crankcase damage
  • A bent valve
  • Damage in the bearings
  • Piston ring damage
  • Harm to the block

When associating the words “metal” and “water,” the first thing most of us think of is rust. This is precisely the case with hydrolock.

If you don’t act quickly to remove the water, your engine will rust, which will likely render it useless.

How To Fix A Hydrolocked Engine

fixing car engine

Whether a fix is possible depends on the amount of water that has entered, as well as how long it’s been there.

If you were moving at a slow rate of speed, when the RPMs were low, you may be able to clear the system of water by yourself.

This involves removing the spark plugs, starting the engine, and then revving it while it’s in park. You should notice water spewing out of one or more cylinders. You should also replace the spark plugs with new ones. Though, in an emergency situation, you should be able to just dry yours off.

It’s also important to wipe down the cylinder walls to remove moisture that might cause corrosion. Though, again, if you don’t have access to a safe space, you can always do this once you are.

The other possibility is that there’s a lot of water inside your engine. In this case, there’s really nothing you can do other than to salvage what you can and replace the rest. In a worst-case scenario, a hydrolocked engine can cost anywhere between $3,000-$8,000.

It’s Probably Better To Go Around That Puddle – Not Through It

driving in splashing water
Don’t drive through a puddle

What’s the best course of action if you think you’ve hydrolocked your engine? Don’t wait – because the longer you do, the better the chances you will end up with corrosion damage.

The worst-case is that your engine is shot and you need a new one. Don’t ignore this one, your bank account will thank you later.

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Joshua Barrett
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Joshua Barrett

Josh Barrett is a writer hailing from the great state of Alaska. While describing himself in the third person is not his forte, writing about any and all things automotive – is. After 13+ years hustling in the exciting world of car sales, he took off to travel the world with his dog Teemo.