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How to Adjust Unloader Valve on Pressure Washer (8 Tips to Follow)

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

Learning how to adjust the unloader valve on the pressure washer is crucial if you intend to use your machine regularly and here is the easiest method.

Are you a new user who recently bought a brand new pressure washer and want to learn details about it? This article is for you to make you understand the importance of an unloader valve and how to regulate it properly.

Most new users don’t know about the unloader valve on a pressure washing machine. If we say effortlessly, an unloader valve is a part that controls the pressure of your machine and directs the water flow towards the spray gun. It needs to be adjusted as we need different types of pressure for different surfaces.

For instance, if you put high pressure on your car’s delicate, it’ll either break down or, you will get a tint what you definitely not want. On the other hand, the low pressure will not be able to remove the tough dirt from your garage, patio, etc. The right pressure is always recommended for any cleaning work to be done properly.

Read Our Latest Guide: Choosing The Right GPM For A Pressure Washer

What is the Purpose of an Unloader Valve?

Not a single part in your pressure washer is less; otherwise, they wouldn’t have been there. Regulating the water pressure on a power washing machine is very important, and an unloader valve adjusts the supply.

As earlier mentioned, all the cleaning surfaces are not the same; some are hard and tough, whereas some are quite delicate.

The delicate surfaces require low pressure and the tough dirt such as oil stain, mold, etc. require high pressure to be cleaned perfectly. The manufacturer put the unloader valve on your machine to easily regulate and acquire the right pressure.

How does an Unloader Valve Work?

The unloader valve redirects the water pressure towards the spraying nozzle from the pump. When you pull the trigger, the valve makes sure that the water flow is directed towards the nozzle through the spray gun. When you release the trigger, the valve redirects the flow of water towards the inlet valve.

In this position, the water circulates inside the pressure washer pump. This is the way your inlet valve changes the direction of water and controls it. When you need your desired pressure, you need to regulate this valve.

How to Adjust Unloader Valve on Pressure Washers?

You might think that regulating the unloader valve and adjusting the pressure is difficult, but it’s not. You just have to follow a simple process to get your desired pressure. Although there are multiple brands and plenty of pressure washer models, most of the machines’ regulating method is almost the same.

how to adjust unloader valve on pressure washer

Before you start, you have to take the following preparation. Here are the few steps:

1. You have to keep your machine on a flat surface, start the engine and keep it at the appropriate rpm which is basically 3700 before load and 3400 under load.

2. Next, you have to remove the nylon lock that is inserted into the unloader valve and shut off the pressure adjusting knob.

3. After that, you have to remove the washer and spring.

4. Leave the threaded piston rod that contains two lock nuts.

5. Now using a wrench, lock these two nuts. Apply three threads off the bottom and put the washer, spring and nut back at their places.

6. Finally, you have to clip the pressure between the HP hose and the pump. Make sure that you see them when you trigger the gun.

Now the adjustment process begins.

1. First, you have to let the air out that is present inside the gun by turning on the water.

2. Check on the gauge and start tightening the spring. Make sure the point where you get the maximum pressure while you pressed the trigger.

3. Once you release the trigger, the pressure spike should be between six and nine percent. Six to nine percent is the ideal point that you need to get. If this is not the case, you have to keep moving the nuts up or down until you get the ideal point or at least less than ten percent.

4. You might need to take the adjustment knob, washer and spring off again.

5. After that, you need to let go of the unloader multiple times to help break in the unloader.

6. As you get the appropriate adjustment, you have to put the washer, spring and knob back in their places.

7. Before you lock it, make sure that the gauge is giving the same reading.

8. At the end put the nylon lock nut back on top of the piston rod and place the cap back on the adjusting knob.

Remember to adjust the pressure while the trigger of your spray gun is engaged. If your trigger is not engaged and you try to release the water your unloader might get damaged, so you have to be cautious while performing this action.


The pressure washer unloader valve adjustment procedure is not very difficult, and you can easily do it yourself. You might find it a little difficult for the first time and from the next it’ll be a piece of cake for you. It is needless to say that adjustment of your unloader valve is necessary to get your required pressure.

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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