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.
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.
The pump can be damaged by air in the inlet water supply or by chemicals that remain in the pump body after using the chemical injection system. Follow these steps to replace a damaged pump.
O-rings seal fittings on the pressure washer pump. Damaged seals allow water to leak from the pump. Follow these steps to replace the O-rings in a leaking pressure washer pump.
The chemical injection valve draws detergent into the pump. If it’s not drawing detergent, use a repair kit to replace the chemical injection valve.
Spray tips vary in pressure and angle of spray. This guide matches the spray tip to the cleaning job.
Follow this advice to winterize your pressure washer.