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How to Fix Pressure Washer Leaking Water from Pump! (Causes and Troubleshooting Tips in 2023)

Fact Checked By Daniel Wood | Post Updated On: April 29, 2023

We often face the problem of a leaking pump and don’t know what to do. This is a common problem often faced by pressure washer users. The reason for this problem is various such as becoming old, the thermal release valve not working correctly, the pressure inside the pump being uneven, etc. When faced with this type of problem, you don’t have to worry much and take the necessary steps to repair it. You have to learn the basic methods of how to fix a pressure washer leaking water from the pump. A leaking pump doesn’t always mean that you have to replace it with a new one.

Water leaking from a pressure washer pump has plenty of causes; getting worn out, damaged thermal valves, and getting cracked are a few of them. To deal with this situation, first, identify the problem and then repair it. When the pump is not too old, you should not think about replacing it immediately and visit a mechanic.

pressure washer leaking water from pump
Possible Cause Symptoms
Worn or damaged seals  Water leaks from the pump.
Cracks or damage to housing Again, the water from the pump is leaking.
Malfunctioning water inlet valve Possibly low pressure or no pressure at all
Malfunctioning unloader valve Low pressure or no pressure plus pump cycling on/off
Worn or damaged o-rings Leaking water from the pump
Damaged or clogged spray gun or wand Same as above
Clogged filter screen Negligible pressure
Damaged or worn pistons Low pressure or no pressure

Can a washer drain pump leak?

A washer drain pump also can leak water and interrupt your work. Among multiple reasons, cracked pumps and worn-out bearings are the main ones. In addition, a drain pump pushes the water out of the drain hose, and if it’s damaged, you cannot repair it. In such a case, the best solution is to replace the pump as soon as possible.

How do I know if my pressure washer water pump is bad?

There are various signs that will indicate you have a lousy pressure washer water pump. A low-graded pump will often leak water which is a bad sign.

A good pump will generate an uninterrupted flow of even pressure. If you see the pressure generated by your pump is pulsating or the flow is uneven, it’s not a good pump. Its manufacturer mentions the power of every pump.

The low-graded pumps will not provide you with proper output, and the pressure will be low. In case of such a problem, you must consult with an expert or replace it.

Why is my Karcher pressure washer leaking underneath?

Whenever you see a leak, you should not panic because, in some cases, it happens because of minor reasons and can be easily solved.

For example, if your machine is new, the leak could be because of a standard thermal release valve. Sometimes the transparent adapter is not sealed correctly, which may leak water. Karcher pressure washer pumps can be repaired, and for that, you need the proper tools to match the model of your machine.

Why is my pressure washer releasing hot water when not in use?

When we don’t use the spray wand for a long time, and the machine is on, the water inside the pump keeps on circulating. This circulation heats up the water inside, causing the thermal relief valve to open and drain the overheated water.

This process allows the cool water to go to the pump, which maintains the system temperature. This process is followed by most of the pumps so that the system remains calm and active.

Why is My Pressure Washer Leaking?

A pressure washer may leak for many reasons, which we should troubleshoot and take proper steps. If you see your machine leaking water from the pump and there is no sign of damage such as a crack, most probably its internal piston seals are damaged.

A pump has pistons inside to pull the water and send it out through the nozzles. These pistons remain sealed so that it can generate pressure.

Leaking water may indicate that one or more seals are either broken or worn out. To check if you have to open the pump and see if the o-rings are worn out, damaged, or out of place.

The pressure generated inside a pump pushes the water towards its walls which might cause a crack if it’s old. In some cases, while in storage, if water remains inside the pump, it expands and causes damage to the seals or the side walls. This situation often compromises the seals and decreases the ability to pressurize the water.

If the outlet seal of your pump is broken, the water will leak straight from its connection to the hose. These outlet seals connect the high-pressure hose to the pump.

The thermal release valve maintains the temperature of your machine. When the water is overheated, it opens to let the hot water out so the cool water can come inside. If the thermal release valve’s seal is compromised, water might always leak.

How do I fix the Pressure Washer Leaking Water from the Pump?

In case of water leakage, you might need to rebuild or replace your pump. If the inlet seals of your pump pistons are damaged or worn out, you need to replace them with new seals. For that, you have to open the pump and check the pistons properly. If you cannot do it alone, it’s advisable to take the help of an expert.

A cracked pump should always be replaced instead of repaired. Immense pressure is generated inside a pump that solid metals can tolerate. Once cracked and repaired pump tends to get the same crack again. Crack repairs cannot be as substantial as solid metals.

If you see the outlet coupling is worn out or broken, you should replace the entire coupling. If you see the coupling is alright, but the o-ring is broken, you can just replace this ring to get your machine working. This repair might not need an expert because simple and easy.

These are the specific troubleshooting steps and maintenance tips that can help you address the common causes of pressure washer leaks:

  1. Worn or damaged seals: You will clearly suspect that the seals cause the leak, and you are right to do so. Now the first thing to do is to turn off the pressure washer and relieve the pressure in the system. Then, it would be best to closely inspect the seals for any visible signs of wear or damage. If you see any tears, cracks, or other signs of wear, you’ll need to replace them. To implement this, you’ll need to disassemble the pump, remove the old seals, and install the new ones.

  2. Cracks or damage to housing: The pump housing may be the source of the leak if you find any cracks or other damage. You might need to replace the pump entirely or get it fixed by a pro to fix.
  3. A clogged or damaged water inlet valve: Little or no pressure might be caused by a malfunctioning water inlet valve. To solve this issue, all you need to do is make sure the inlet valve is not clogged or damaged. If it looks to be clogged or damaged, you have a problem to solve.
  4. Malfunctioning unloader valve: A malfunctioning unloader valve can cause low pressure or no pressure and can also cause the pump to cycle on and off repeatedly. To troubleshoot this issue, you should check the unloader valve for any visible signs of damage or wear and replace it if necessary.

  5. Worn or damaged o-rings: O-rings are tiny rubber rings that help create friction or a seal between different parts of the pump. If they are damaged, they can cause leaks. To fix this, you’ll need to replace the o-rings right away.

In addition to troubleshooting the causes of leaks, you must perform regular maintenance on your pressure washer. This includes:

  • Checking the oil level and adding more as needed
  • Inspecting and cleaning the air filter
  • Checking the fuel level and refilling as needed
  • Inspecting and cleaning the spark plug
  • Flushing the pump with clean water after each use
  • Storing the pressure washer in a clean, dry, and protected area.


Leaking water from a pressure washer is a severe issue as it may lead to more significant damage if not repaired on time. When the machine is new, you will hardly find these types of problems, but you should immediately contact your seller.

As advised earlier, a cracked pump should always be replaced. However, when your machine becomes old, you will often see a water leaking problem, and you should troubleshoot the problem and take necessary precautions.

About Daniel Wood

Daniel has completed his graduation mechanical engineering from a reputed university in US. He worked as a technical engineer in a pressure washer manufacturing plant for four years. He has a great passion for mechanical devices and has opened a workshop where he does research on various machines in his leisure time. His high interest in technology made him an expert in commercial and residential pressure washers.

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