How to Replace Pressure Washer Pump Check Valves [With Pictures]

When a pressure washer pump fails, it tends to be the small parts that go bad—for example, the check valves.

Fortunately, if your check valves need to be replaced, you can skip the mechanic. We’ve provided a detailed guide on how to replace them yourself.

If you get confused on any of the steps, check out the photo gallery on the bottom for extra help.

Ready to establish your DIY bonafides and get your pressure washer working again? Read on to find out how to replace your pressure washer pump check valves.

Since you’ll likely be making this repair with the pump still attached to the pressure washer, ensure that when you lay your washer down, the engine is positioned in such a way that oil will not leak into your pistons or carburetor.

If you do need to remove your pump from your machine, the instructions in our Rugged U pressure washer video might help.

STEP 1: COLLECT THE NEEDED TOOLS

For this project, you'll want to have the following:

• Replacement check valves (see SKUs below)
• Replacement check valve seals (highly recommended)
• 6mm Allen wrench
• Needle-nose pliers
• Tweezers (optional)
• Flathead screwdriver
• Ratchet and socket
• Calcium, lime, and rust remover (CLR)
• Disposable toothbrush (pro tip: don’t use your spouse’s)

Here are the SKUs for products you might find helpful for this repair along with the associated fitment information. You can also use the Verify Fitment widget on our listings to help you determine compatibility.

Replacement Check Valves SKU - 101351, 100234, 100248

Replacement Check Valves with O-Rings SKU - 100223, 100243

Replacement Water Seals SKU - 100247

Replacement Bushings SKU - 100241

Replacement O-Rings SKUs - 100231, 100238, 100254

Associated Models - AR2233, AR42123, AR1828, AR2864, AR2840561, AR42122, AR2190, AR2237, AR2701

STEP 2.3 - The head will have three open areas where the pistons are. If any of the bushings there are stuck, remove them and set them aside for reinstallation. Carefully remove the water seals that are holding in the check valves and set these aside.

STEP 2.4 - Carefully remove the check valve parts . Note that the seal, housing, valve, and springs might pull free in one piece or in parts. Avoid damaging the sidewalls of the head. If the seal is hard to remove, as long as one of the bolts attaching the head to the pump is small enough, you can sometimes wedge it into the middle of the seal to help remove it.

STEP 3: REMOVE DISCHARGE SIDE CHECK VALVES

STEP 3.1 - For the discharge side, use a ratchet and a socket to remove the valve plugs. Be careful of the O-ring as you remove the plugs.

STEP 3.2 - Look over the plugs to see if the O-rings will need to be replaced before tightening. (It’s best to make the repair now while the unit is apart.)

STEP 3.3 - As before, carefully remove the check valve parts and remember that they might pull free all in one piece or separately. Be careful not to harm the sidewalls. Again, you might be able to use a bolt to help remove the seal like in step 2.4.

STEP 4: CLEAN PUMP HEAD

STEP 4.1 - Next, gently clean the pump head to remove any calcium buildup using a toothbrush and a mix of CLR and water.

STEP 4.2 - Rinse the head with water thoroughly and allow it to dry before beginning reassembly.

STEP 5.3 - Replace the plugs, tighten them down with your ratchet, and use a torque wrench to set to 219" lbs.

STEP 5.4 - For the check valves on the bottom side of the head, place them seal-first into their respective openings. Using a flat-faced tool or your Allen wrench, apply gentle pressure to seat them into place.

STEP 5.5 – Use new seals to replace the black seals that cover the check valves.

STEP 5.6 - Set the seals in place with the grooved side of the seal facing down into the head. When they’re properly in place, the seals will sit flush with the inset rims of the manifold.

STEP 6: RECONNECT HEAD TO PUMP

STEP 6.1 - Place the bushings into the new head with the grooves facing outwards. If you install them the wrong way, you could harm your seals.

STEP 6.2 - Set your new head onto your washer’s pistons so that it is securely on the pump.

STEP 6.3 - Put Loctite on your bolts so that they won’t be jarred loose while your pressure washer is operating. The type of Loctite (red or blue) you’ll want to use depends on whether you think you’ll need to remove the bolts later on.

STEP 6.4 - Tighten your bolts by hand. After that, use the Allen wrench to tighten them to 221” lbs. of torque. However, be sure not to tighten them too much; if you do, you could break the heads off or strip the aluminum threads in the pump wall.

You’re just about finished! With your check valve replacement complete, it’s time to test everything out. Make sure you only test the unit while water is running through the system.

Conclusion

Whew! You’ve successfully replaced the check valves on your pressure washer pump. Take a moment to congratulate yourself on a DIY job well done.

If you have questions or have further issues with your pressure washer pump, contact our customer service department. You can also check out our blog post on troubleshooting a pressure washer pump for some other suggested steps to take.