How to Rebuild a Pressure Washer Pump: A Basic Guide

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How to Rebuild a Pressure Washer Pump A Basic Guide

Arguably, the most important part of your pressure washer is its pump, as it regulates water flow and allows the entire unit to work as it should.

Without a pump, you’ll mainly have a piece of junk sitting in your garage, which is common amongst homeowners.

However, it doesn’t mean that you can’t learn how to rebuild a pressure washer pump on your own. but you do need to make sure that you have the best pressure washer pump oil for your pump at hand.

Hence, we’ll discuss the specific tips for repairing a pressure washer pump as well as what a professional repair shop can do for you if you don’t want to handle the task on your own.

A Systematic Guide for Learning How to Rebuild a Pressure Washer Pump

As mentioned, knowing how to repair or rebuild the pump in your electric pressure washer gives you the ability to save a lot of money as you won’t have to worry about heading out and buying a brand-new unit.

By following these steps, you’ll be able to diagnose and fix any issues so that your pressure washer can return to its normal operating condition.

Step 1: Troubleshooting Before You Start

The very first thing you’ll need to do is figure out what the problem may be, as this will help you figure out what part of your pump needs to be fixed.

There are a few important things to pay close attention to including whether you have a warranty or not and the level of water flow.

  • Warranty

First and foremost, you’re going to want to think about whether your gas pressure washer is still under warranty as this can help you save a lot of time and effort.

The vast majority of pressure washer falls under a one or two-year warranty, which means that you can typically send the unit to the manufacturer for repair or replacement.

If you’re unsure, contact the manufacturer’s customer service department and give them the model number to determine if they can repair it free of charge.

  • Low Water Flow

If you’ve noticed that your pressure washer simply isn’t as powerful as it should be, that could be a result of dirt clogged in the pipes or even a faulty connection to a water source.

You’re going to want to inspect the intake valve and filter screens to make sure everything is clean and clear. You’ll also want to look at any valves and O-rings to make sure there aren’t any signs of leakage.

  • Zero Water Flow

This is the most significant indicator of a faulty pump, and if you’ve noticed that your pressure washer has no water flow, you’ll need to shut it off and start to follow the repair process.

Step 2: Siphoning the Oil

With the help of a siphon, you must get rid of all the oil in the pressure washer and as you’re removing it, take a look at its quality since cloudy oil likely means that there is water in it.

Once you have removed all the oil, replace it with new oil and remember, pressure washers mostly use an exceptional type of oil.

Step 3: Prime the Pressure Washer

Using the primer on the side of your pressure washer, try to prime the pump, and if you find that you still aren’t getting a substantial amount of flow when you start the washer, you’re going to want to disconnect the discharge hose.

You can then release any air from the pump and then reconnect the discharge hose and restart the pressure washer.

Step 4: Cleaning the Chemical Strainer

A clogged chemical strainer can not only cause your pressure washer to perform poorly, but it can also create a clattering noise that makes it seem like the pump is broken.

To clean the chemical strainer, you have to unscrew it from the hose and run water through the strainer, then use a small brush to clean any debris.

You can then reinstall it to the hose and if your pressure washer still isn’t performing, it’s time to replace the pump.

Step 5: Choosing a Replacement Pump

Unless you have experience in engineering and working with fine components, it’s easier to install a new pressure washer pump rather than learning how to rebuild a pressure washer pump, not to mention it’s also safer.

First, you need to figure out whether your washer uses a triplex or axial pump.

In most cases, the less expensive your pressure washer is, it likely has an axial cam pump, but if you have an expensive professional-grade one, it likely uses a triplex pump.

Step 6: Disconnecting the Old Pump

Disconnect the wire that connects the spark plug to the machine by pulling it out, and then disconnect any hoses that are directly connected to the pump (inlet hose, spray nozzle, outlet hose, and chemical injection tube).

During this process, make sure that you’re able to clamp the end of the chemical injection tube as you’re certainly not going to want to spill any chemicals on yourself or the other internal components of the pressure washer while removing the tube.

Step 7: Uninstalling the Pump

Once you have disconnected all the components on the pump, it’s time to uninstall the old pump by loosening any screws or bolts and working the pump out of the pressure washer.

Once it’s been removed, you have to inspect the thermal relief valve which is responsible for pushing out hot water in the event of the internal water becoming hotter than it should.

If this component is broken, you’re going to need to install a new one on your new pump, and if your new pump doesn’t have a thermal relief valve, but your old one is in working condition, you can easily transfer them.

Step 8: Mounting the New Pump

Now it’s time to install the new pump into your existing pressure washer by using the same bolts and/or screws that were removed from the older pressure washer.

If you find that there’s an excessive amount of dirt buildup where the old pump was, you can use a soft rug and rubbing alcohol to clean any components before the new installation.

Putting in the new pump is relatively simple, as you’re going to do the complete opposite of what you did when you were removing the old one.

After the screws have been secured, you’re then going to want to attach all the tubes and the spark plug back to the pump, ensuring they are connected tightly. Be sure to take extra care to seal any connections with pipe thread sealing tape to prevent leaks.

Step 9: Testing the Pressure Washer

As the final step, you’re going to want to turn your pressure washer on and see if the new pump is working correctly.

As long as you followed the above steps, and there isn’t another problem with your pressure washer, you should have access to a perfect pressure washer once again.

If it’s still not working, it’s advised that you bring it to a professional for a proper diagnosis and repair.

Final Thoughts

Pressure washers are amongst the most versatile pieces of outdoor equipment, which is what makes it so frustrating when they stop working.

At times, simply replacing the pump is easier and safer than trying to repair the delicate components within its housing.

At the end of the day though, if you aren’t sure about your repair or replacement skills, it’s always best to bring your tools to an established mechanic or engineer for their professional assistance.

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Adam White is the founder and chief editor at He has years of experience from years of Gardening, Garden Design, Home Improvement, DIY, carpentry, and car detailing. His aim? Well that’s simple. To cut through the jargon and help you succeed.