Pressure Washer Unloader Problem, With Fixes and Helpful Tips


Pressure washers are super helpful machines for cleaning large surfaces and various objects. In general, pressure washers are reliable machines, but they can have some problems now and then. One of them is a problem with the pressure washer unloader valve. Such a fault can damage the pump and motor, so it is important to fix it.

Pressure Washer Unloader Problem With Fixes:

When the unloader valve of a pressure washer is not working correctly, you will see inconsistent and sudden changes in the output pressure. Or the pump is running hot. Test the unloader valve by adjusting the tension spring and monitoring the output pressure. If the unloader valve is stuck, remove the retaining pin and take out the unloader valve. Clean the pin and pore. If that does not help, replace the unloader valve.

Pressure Washer Unloader Problem, With Fixes and Helpful Tips 1

This article will provide you with information on pressure washer unloader issues. How to diagnose and fix a problem. And how to test and adjust the unloader valve.

How Do I Know If My Pressure Washer Unloader is Faulty?

To diagnose a problem in the unloader valve of your pressure washer, you need to check the output pressure of the pressure washer. If it is inconsistent and you see sudden changes in the pressure, it is clear that your unloader valve has a problem. Other signs include your pressure washer pump running hot and excessive load on the engine.

The unloader valve in de pressure washer diverts the water flow through a bypass when the trigger is not pressed. It will respond to the increase in pressure when the trigger is released. When it would not divert the water flow, it would strain the pump and engine as it can not discharge the water. The engine load will quickly increase, and the pump will run hot. And over time, it can even damage the pump. The unloader valve is often also used to adjust the output pressure.

When the unloader valve of the pressure washer fails, certain signs can be seen. One of the most apparent problems with the unloader valve is less output pressure and a lower water flow. If the valve does not work correctly, the pressure washer pump will get hot, and more power is asked from the engine. If you have a gas pressure washer, you can hear more engine noise due to the higher load. Water leaks and inconsistent output pressure are also signs that there is a problem with the unloader valve.

How Do You Test a Pressure Washer Unloader Valve?

You can test the unloader valve of your pressure washer by adjusting the tension spring of the unloader valve. This should lead to an increase or decrease of the output pressure. If you see this, it’s a sign that your unloader valve is working correctly.

The easiest way to check the unloader valve is by adjusting the spring of the unloader valve. Mark the setting before changing it. That way, you can easily set it back after changing it. When you move the spring, you should see the output pressure of the pressure washer change. You should be able to lower it and set it higher. If this is the case, the unloader valve is working fine. Ensure that you set it to the correct level.

How Do You Adjust a Pressure Washer Unloader Valve?

Adjusting the unloader pressure valve is a tricky process. The goal of the unloader valve adjustment is to find the spot where the pressure is maximum. And the pressure spike when you release the trigger is minimal. If you have a gas pressure washer, check the RPMs of the engine. Remove the top, lock the nuts. Clip the pressure gauge and start tightening the spring. Once the spring is adjusted, engage the trigger to prevent blockages in the unloader valve. Adjust the knob until you find the spot where pressure is maximal, and the spike is minimal.

The unloader valve of a pressure washer has a tension spring which is responsible for releasing the pressurized water when the trigger is pressed. The tension spring is also responsible for decreasing the pressure when the trigger is released. By adjusting the pressure washer unloader valve, the goal is to find the ideal setting for the tension spring.

There are five steps to follow to find the best setting:

● Step 1: Check the runs per minute of the engine

Before we begin with adjusting the unloader valve, make sure that the engine or motor of your pressure washer is in good condition. If you have a gas pressure washer, check the RPM. It should be around 3700 RPM without load. And decreases when power is needed. When you have an electric model, this is not needed, as the electric motor is only turned on when pressure is needed.

● Step 2: Remove the top and take off the nob

Remove the nut from the top of the unloader valve and take off the plastic pressure adjusting knob. Then remove the thin washer and the spring. You will see a threaded piston and rod with two locking nuts if you have successfully removed them.

● Step 3: Lock the nuts, clip the pressure gauge and start tightening the spring

Lock the two nuts that you see on the rod together with a wrench. Put the spring washer and black adjusting knob on. If you have a pressure gauge, attach it between the pump and pressure hose. You can use it to see the output pressure when you press the trigger. If you do not have a pressure gauge, you have to do this by sight. Try to spray at the same distance to the same spot to compare the different settings easier.

Turn the water on and press the trigger. Ensure that all the air from the pump is released and only water comes out of the nozzle.

Now press the trigger. Look at the pressure gauge. Start tightening the spring. The pressure should increase. Now release the trigger. You will see that the pressure spikes up. The goal is to find the setting where the spike is somewhere between 5% to 10%. This is the spot where you need to stop adjusting the knob. It would be best not to have more than a 10 % spike when you release the trigger. If it is higher, it can damage the pump over time.

For example, if you set the pressure to 3000 PSI. The pressure spike shouldn’t exceed 3240 PSI when you release the trigger.

● Step 4: Break in the unloader valve

To break in the unloader valve, press the trigger and let it flow for 5 to 10 minutes. Repeat this. This is to ensure that the unloader valve does not hang up.

● Step 5: Adjust the knob until you find the spot where pressure is maximal and the spike is minimal

Keep the machine running and continue adjusting the knob. If the nuts are too low, you can move them higher. Try to find the setting where the pressure is at its highest and the spike as low as possible. Like mentioned earlier, the spike should not exceed 10%. And if possible, it should be lower if you release the trigger. Once you find the spot, take off the adjusting knob, washer, and spring and tighten the nuts firmly with wrenches.

Crank down the spring to bottom it out on the two nuts. Check the pressure, and spike again. If the pressure and spike are both ok. Screw the nut on top of the piston rod and pop the cap on top of the adjusting knob.

How Do You Free a Stuck Unloader Valve?

To free a stuck unloader valve, remove the retaining pin and take out the unloader valve. Ensure that the pin on the valve is moving freely. Clean the pore using a pin and grease the O-rings.

You can easily free a stuck unloader valve by following some simple tips. All you need is a screwdriver and a pin that you will use to clean the blocked pore of the unloader valve.

To start, remove the retaining pin above the unloader valve. Put the screwdriver under the pin, and lift it upwards. Now you should be able to remove the pin. Make sure to put the pin in a safe place. I wasted too much time looking for it. If you do this for the first time, I recommend making some images or a small video of the process. This can be of great help later if you have to reassemble it.

Once you have taken off the retaining pin, remove the unloader valve. Put the screwdriver behind the last spring and move gently outwards. The unloader valve should pop out.

Once the unloader valve is out, make sure that the small and long pin on the valve is free and moving. You can check this by gently inserting pressure with your thumb on top of the pin. If the pin isn’t moving freely, clean it. Clean the unloader valve and unblock the pore that is present just below the spring. I recommend using a tiny pin to clean the blocked pore. Ensure that there is no debris stuck. After unblocking the pore, you need to grease the O-rings so that they face minimum friction.

Now it’s time to assembly the unloader valve. For reinstalling, you need to reverse the process. Put the unloader valve back in place and hit it gently with the screwdriver. Once the unloader valve is in its place, put the retaining pin back.

If the fix does not help, and the problem remains, replace the unloader valve.

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