How To Adjust Pressure Washer Unloader Valve

Pressure washers are one of the most convenient machines mankind has ever build. With its power, you can wipe away any unwanted material, on any kind of surface, in no time at all. With the best residential pressure washer, you can clean cars, patios, driveways, upholstery, cabins, and many other surfaces in your hose.

All in all, a pressure washer is super easy to assemble and use, but there are some things that you need to keep in your mind while using a pressure washer. One of the most important of these things is adjusting the unloader valve.

What is an unloader valve and what does it do?

Like nozzle, hose, and spray gun, a perfectly adjusted unloader valve also increases your pressure washer’s performance by some factor. By adjusting the unloader valve, you are adjusting the pressure, the amount fuel and energy the pressure washer is consuming. Furthermore, if you adjust your pressure washer’s unloader valve perfectly, it may also increase the life span of your pressure washer.

The unloader valve is responsible for regulating the water between the inlet, pump and the outlet. When you press the trigger of your spray gun, it makes sure the water smoothly flow toward the nozzle. When you release the trigger, it redirect the water towards the inlet and hence it make sure there is safe circulation of water inside the pump.

Leaving the unloader valve unadjusted may bring harm to the surface you are cleaning. For instance, if you are cleaning your car’s mirror and the pressure is too high, you might damage the mirror with high pressure. In order to avoid such disasters, you will need to adjust the unloader valve.

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Things to keep in mind while adjusting the unloader valve

Adjusting the unloader valve is easy and simple, but there are some things you need to keep in mind before adjusting, you need to perform the following tasks.

  1. Make sure the pressure washer motor is running, before load, set the rpm to 3700 and 3400 after loading.
  2. Take off the nylon lock, shut off the water pressure adjusting knob and remove it from its bay by spinning it gently.
  3. Remove the washer and the spring from the unloader valve, you will see threaded piston with two locknuts.
  4. Lock these two nuts using a wrench, apply 3 threads off the bottom and then put the washer, the spring and the locknuts back in their place.
  5. Lastly, clip the pressure gauge assemble between the pressure washer pump and the hose. Doing so will ensure the perfect adjustment of the unloader valve.

After you have made sure you have done all of the above things, you will carry out the adjustment process that includes…

Adjusting the unloader valve

  1. First you need to take out the water and the air that remains in the nozzle and the hose by turning on the outlet valve. Do not turn off the valve until the hose has no air or water in it.
  2. Tighten the spring and also keep an eye on the pressure gauge assembly. Press the trigger on the spray gun and notice the point where you get maximum pressure. Make sure the pressure spike is around 6-9% when you are disengaging the gun.
  3. In case you don’t get the pressure spike around 6-9%, keep moving the nuts until you reach the ideal percentage. If moving the nuts doesn’t get the job done, you will have to unlock the nuts, washer and the spring.
  4. When you have reached the ideal percentage i.e. less than 10%, you need to use the spray gun for at least 15 minutes. Doing so will ensure that the unloader valve don’t hung up by making the perfect break in the valve. If you want a pressure of 3000 PSI, make sure the pressure don’t exceed 3300 psi when the trigger go off.
  5. If you have reached the settings you need, place the nuts, washer and the spring back in their place. Check the ratings on the pressure gauge and make sure the ratings are the same. After that screw the locknuts back on the piston rod and place the cap of the adjusting knob.


Buying the best commercial pressure washer is important but one thing that is even more important is maintaining your pressure washer. No matter good your pressure washer works, if you don’t maintain and optimize it, it won’t give the best results. One of the most important components of optimization is setting the unloader valve, after reading this article you should be able to safely adjust your pressure washer’s unloader valve and get the best out of your pressure washer.

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