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

Do you know what a hydrolocked engine is? In this guide, I will talk you through a critical relationship between your car's engine and water.

Aspiration is that coughing and suffocating 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 hydrolock, meaning they all stop moving at once.

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

Fortunately, in this guide, I will clarify all the necessary information about a hydrolocked engine. This also involves what causes an engine to hydro lock, if it can result in harm, and how to rectify 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 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 the hydro lock to occur from other liquids, like oil or coolant. However, remember 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 slowly, 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.

A few of these consist of:

  • 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 might 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 is vital to wipe the cylinder walls to get rid of dampness that may cause damage. However, if a secured area is not available, the cleaning can be done later.

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 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.

You Might Love These

0W 20 vs 5W 20 Oil
0W-20 vs 5W-20 Oil: What’s The Difference?
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.