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What is a Hydrolocked Engine and How Bad is It?

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What is a Hydrolocked Engine and How Bad is It?

Hydrostatic locking—more commonly referred to as hydrolocking—happens when an engine fills with liquid, causing it to seize up. This usually happens if a driver plows their vehicle into a deep puddle, forcing water into the cylinders and preventing the engine from turning over. Depending on the extent of the damage, you may be able to fix the problem on your own.

Hydrostatic locking will cause an engine to stall out and can damage the head, connecting rods, piston ring, crankcase, bearings, and valve. The extent of the damage usually relates to how fast a driver was going when they hydrolocked their engine. If they were running at high RPMs, the repairs could cost as much as $10,000. 

Before you panic, take a moment to learn more about hydrolocking and how it affects your engine. If you are lucky, you may be able to fix the problem by yourself and avoid an expensive repair. This guide will explain how the phenomenon occurs and why it’s often so destructive.

What is Hydrostatic Locking and How Does it Affect an Engine?

Combustion engines are designed to compress a mixture of air and fuel. This mixture is then ignited, causing the pistons to move up and down. The up and down movement of the pistons turns the crankshaft, which in turn rotates the wheels.

If water seeps into an engine and floods the cylinders, it will compress just like air and fuel. However, when the mixture is ignited, the water will turn to steam and cause the pistons to become locked in place. The sudden expansion of gases can also cause gaskets to blow out, parts to crack, and the engine to overheat, which can lead to even more damage.

Incompressible water inside the piston bends or breaks the connecting rods and pistons, resulting in hydrolocking damage.

The most common cause of hydrolocking is driving through a large puddle of water. This can happen if you hit a puddle that’s deeper than you think or if you drive through a flooded road. Hydrolocking can also occur if your vehicle is submerged in water. This is more common with smaller vehicles, such as motorcycles, ATVs, and golf carts.

It’s also possible to hydrolock your engine by pressure washing it while it’s running. The high-pressure water can force its way into the cylinders and cause the engine to seize. This is generally uncommon with modern vehicles, though, as they’re designed to be more resilient to water.

Signs of Hydrolocking

Depending on how quickly you’re driving, you may not notice that water has seeped into your engine. However, the more you drive, the more likely it is that you’ll start to notice some strange symptoms. The first sign of hydrolocking is usually a loss of power. The engine will feel like it’s struggling to run and may eventually stall out.

Many people attempted to drive through water in a flood and ended up stranded.

In some cases, the engine may run for a few minutes before stalling. If you try to restart the engine, it may turn over but not start. Or, it may start but stall out again after a few seconds. In either case, it’s likely that the engine will make strange noises, such as a knocking, gurgling, or hissing sound.

Generally, though, the best way to tell if your engine is hydrolocked is to remove the spark plugs and check the cylinders. If water has seeped into the cylinders, you’ll see water on the plugs or in the cylinders themselves. It’s also possible to check for water by removing the oil dipstick. If water has been mixed into the oil, it will change to a milky white color.

How RPMs Affect the Extent of the Damage

If you hydrolock your engine at high RPMs, the damage will be much worse than if you’re driving at low RPMs. This is because the pistons are moving much faster and are under more stress. When the engine is hydrolocked, the pistons will stop suddenly, which can cause them to shatter.

Shattered piston

Even if the pistons don’t shatter, the sudden stop can cause them to bend. This can damage the connecting rods, which will then need to be replaced. The damage can also cause the crankshaft to bend, which is an even more expensive repair.

How a good piston connecting rod looks compared to a bent and hydrocloked damaged one. Image via 996 Revolution

If you’re driving at low RPMs, it’s less likely that the pistons will be damaged. However, the water can still cause the engine to overheat, which can damage the gaskets, bearings, and valves. In either case, it’s important to have the engine inspected by a mechanic to determine the extent of the damage.

Can You Fix the Problem On Your Own?

If you catch the problem early enough, you may be able to fix it without taking the vehicle to a mechanic. This usually involves draining the water from the cylinders and then changing the oil. You’ll also need to inspect the engine for any other damage, such as cracked gaskets or damaged bearings.

To drain the water from the cylinders:

  1. Remove the spark plugs
  2. Turn over the engine a few times to allow the water to drain. You may need to do this a few times to get all of the water out.
  3. Dry the plugs and put them back in.
  4. Change the oil and filter. It’s important to use fresh oil, as water can damage the oil and cause it to break down.
  5. Inspect the engine for any other damage.

If you’re not comfortable doing this yourself, or if you can’t get all of the water out, it’s best to take the vehicle to a mechanic. They’ll be able to properly diagnose the problem and make the necessary repairs.

How to Prevent Hydrolocking

The best way to prevent hydrolocking is to avoid driving through deep puddles. If you can’t avoid the puddle, slow down as much as possible. This will minimize the amount of water that gets into the engine. It’s also a good idea to check the depth of puddles before driving through them. If the puddle is more than six inches deep, it’s best to find an alternate route.

You should also avoid driving through flooded roads. If the water is deep enough that it’s coming up over the tires, there’s a good chance it will seep into the engine. In this case, it’s best to find an alternate route. Finally, if you’re going to be driving in an area with a lot of puddles, it’s a good idea to have a snorkel installed.

This will allow the engine to “breathe” even if it’s submerged in water. A snorkel is a tube that goes from the air filter to a higher point on the vehicle, such as the roof. This will allow the engine to get air even if it’s submerged, preventing hydrolocking.

Final Thoughts on Hydrolocking Your Engine

Hydrolocking your vehicle’s engine can cause widespread damage to the head, valves, pistons, and crank head, costing you thousands of dollars in repairs. Fortunately, though, it’s an easy problem to avoid by driving carefully in dangerous weather conditions. If you ever encounter a deep puddle or flooded section of road, use caution, and find a new route if the water comes over your tires.

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