This step-by-step repair guide explains how to replace a pressure washer unloader valve. When you let go of the trigger on the wand, the unloader valve opens to recirculate pressurized water to the pump, so the water won't overhead and damage the pump. If the unloader valve clogs or won’t open, the thermal release valve opens and sprays steamy water from the pump. Conversely, if the unloader valve won’t close, water pressure to the spray nozzle decreases drastically. If the pressure washer unloader valve isn’t working, replace it using the manufacturer-approved replacement part. The unloader valve kit includes the O-ring and all parts needed for the repair.
Follow these steps to replace the unloader valve in Craftsman, Briggs & Stratton, Husqvarna, Troybilt and Snapper pressure washers.
Torque wrench (optional)
15 minutes or less
15 minutes or less
Disconnect the spark plug
Pull the spark plug wire off the spark plug on the pressure washer engine.
Remove the unloader valve
Use an open-end wrench to turn the unloader valve counter-clockwise to remove.
Loosen the unloader valve.
Remove the unloader valve.
Install the new unloader valve
Install the O-ring from the kit on the new unloader valve.
Lubricate the O-ring on the new unloader valve with silicone lubricant.
Thread the new unloader valve into the pump and tighten.
Tip: : If you have a torque wrench, tighten the new unloader valve 10-12 ft.-lbs.
Install the new unloader valve.
Reconnect the spark plug
Reconnect the spark plug wire to the engine.
Check pressure washer operation
Start the pressure washer and check for water leaks at the new unloader valve.
Make sure that the new unloader valve works properly.
Warning: Undertaking repairs to appliances can be hazardous. Use the proper tools and safety equipment noted in the guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs should only be performed by a qualified technician.