How to Replace a Pressure Washer Unloader Valve

 

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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.

Repair difficulty:
     
Time required:

Less than 15 min.

Parts Required

  • Unloader valve kit

For manuals, repair guides, and specific part recommendations, enter your model number.

Tools Required

  • Wrench set
  • Silicone lubricant
  • Torque wrench (optional)
  • Work gloves

Before you begin

Wear work gloves to protect your hands.

Instructions

 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.

Step 1: Disconnect the spark plug

Pull the spark plug wire off the spark plug on the pressure washer engine.

Step 2: Remove the unloader valve

Use an open-end wrench to turn the unloader valve counter-clockwise to remove.

Step 3: 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.

Step 4: Reconnect the spark plug

Reconnect the spark plug wire to the engine.

Step 5: 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.