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choose and replace the pressure washer pump


If your pressure washer is turned on but cannot pressurize the water, do not give it up; it may be that the pump is broken. If you invest in a professional high-pressure washer with an axial cam or three-cylinder plunger pump, replacing the pump is much cheaper than replacing the entire high-pressure washer. Moreover, changing the pump is easier than you think. On the other hand, most entry-level high-pressure washers have non-replaceable swing pumps, in this case, you'd better buy a brand new unit. Read the following to learn how to tell which type of pump you have, how to choose a replacement, and how to install a new pump.

Types of pressure washer pumps

you need to make sure that the replacement pump you buy is compatible with your current machine. For this, you need to know type of pump. You will encounter three types of high-pressure washer pumps: swing pumps, axial lobe pumps, and triplex pumps. Let's examine each in more detail.

pressure washer swing pump

The swing pump is an entry-level option with an efficiency of approximately 70%. They use a rocking plate connected to the drive shaft to push the piston back and forth to generate suction. This will push the water out.

swing pump advantage:

  • They push the water out with great force.

  • They use high pressure.

  • They are self-priming.

swing pump disadvantage

  • Their efficiency is only about 70%.

  • They are difficult or impossible to repair.

  • Their water flow is low.

pressure washer axial cam pump

Axial cam pumps, sometimes called swash plate pumps, are better than swing pumps, but not as good as three-cylinder pumps.

The axial cam pump is angled so that the internal piston moves from one side to pump water and then pushes out the water to the other side. This makes the service life of the pump longer than the swing pump.

To determine whether it is an axial flow pump, check the connection between the pump and the motor. If the drive shaft of the motor points directly to the brass valve, it is an axial lobe pump, which means that the drive shaft directly rotates the cylinder that pressurizes the water.

axial cam pump advantage

  • 1. Self-priming.

  • 2. More effective than swing pump.

  • 3. You can manually adjust the water flow.

  • 4. Lightweight and compact.

  • 5. Their service life is longer than swing pumps.

axial cam pump disadvantage

  • 1. They become very hot and take a long time to cool down.

  • 2. They have excessive vibration.

pressure washer three-cylinder pump

The working principle of three-cylinder pumps is similar to that of a car engine because they have a crankshaft and connecting rod to drive position-acting pistons, which suck and discharge water in each stroke. They are made for professional-grade high-pressure washers because they can discharge high pressure. They can be used for thousands of hours before maintenance or repair is required.

Parallel to the drive shaft is a three-cylinder pump. This means that the drive shaft provides power to the crankshaft, which in turn moves the plunger rod that pressurizes the water.

Three-cylinder pump advantage

  • 1. Their life span is very long, about 10 years.

  • 2. They use very high water pressure.

  • 3. You are unlikely to have a leak.

  • 4. Nearly 90% efficiency.

Three-cylinder pump disadvantage

  • 1. These pumps are usually more expensive.

pressure washer pumppressure washer pump

How to choose the best high pressure washer pump

When choosing a high-pressure washer pump, you should consider a few things to find the best pump for you.

  • Apppcable pump type

    Before choosing, the most important thing you should check is which pump is compatible with your high pressure washer. Most household models use swing pumps or axial flow pumps, while more powerful models require three-cypnder pumps. Since there are huge differences between the structure and size of these types, it is important to understand the exact type you need.

    If you cannot find the user manual for the high pressure washer, you must open the housing and see how the pump is connected to the motor. In an axial pump, the drive shaft directly rotates the cypnder, so it will turn to the brass valve. In a three-cypnder pump, the drive shaft runs next to the brass valve and is connected to the crankshaft. Make sure to also measure the shaft diameter.

  • size

    In terms of size, there are two factors to consider. First of all, how big is the pump and do you have space? The circumference of a high-pressure washer pump is usually about 7 inches, more or less, but some pumps can reach up to 11 inches in length.

    Secondly, is it suitable for your pressure washer? You should check the connection point and make sure it fits your pressure washer.

  • Match PSI and GPM

    You should match the PSI (pounds per square inch) and GPM (gallons per minute) ratings of the replacement high pressure washer pump to your high pressure washer. Buying a new pump is not the time to try to upgrade the PSI/GPM rating of a high pressure washer. Even if technically you can install a more powerful pump, the rest of the pressure washer may not be able to withstand the additional power. If you install a higher-rated replacement pump, the most pkely scenario is that your hose or nozzle has burst, or the engine cannot meet the new requirements. So – match the PSI and GPM ratings to the current specifications of your machine.

    For example, if the maximum PSI of your pump is 2500, and the maximum PSI of your high pressure washer is 3500, you will never be able to use the full potential of the high pressure washer.

  • Durabipty

    Of course, you want something that can last a long time. The three-cypnder pump is the most durable and can be used for thousands of hours or up to 10 years. Your next best choice is an axial lobe pump, which can last for 5 to 8 years, and then consider using an oscillating pump for about 2 to 3 years.

    The material of the pump should also be considered. Aluminum or steel, or other strong metals, is your best choice.

  • Easy to install

    Some high-pressure cleaning pumps are easier to install than others. If this is important to you, check the manufacturer's and customer's evaluation of ease of installation. A simple installation should only take about five minutes.

How to replace the high pressure washer pump?

Replacing the pump of a high-pressure washer is not as difficult as it sounds. Next, let us understand the basic steps of replacing the high-pressure washer pump.

  • Check your user manual

    In this guide, we will outpne the steps you should take to install a new pump. However, be sure to carefully read the instruction manual that comes with the new pump and consult the instruction manual of the high-pressure washer.

  • Disconnect the old pump

    You don't need many tools to replace the high pressure washer pump. In most cases, you only need:

    Wrench and Allen wrench (anti-pinch)

    First, you should remove all components connected to the pressure washer. This includes water supply and outlet hoses, as well as chemical injection pipes. If you own a high-pressure washer in a plastic casing, you should gently disassemble the casing to expose the internal components of the machine.

    Once you have access to the inside of the equipment, you should remove the old pump from the pressure washer.

    Loosen the bolt that connects the pump to the engine with a suitable size wrench or Allen key. When you remove the bolts, your pump will remain installed on the crankshaft. You should be able to spde it down. If it does not fall off easily, make sure that there are no extra bolts on the shaft itself. If your shaft is rusty, you may need to pull harder to remove it. The rectangular key may fall off the shaft of the pump. Remove it and put it back in the shaft.

    After the old pump is turned off, apply an anti-seize agent to the exposed engine shaft for easy installation and disassembly in the future and avoid corrosion. This is important because metal parts are always in contact with water.

  • Install the new pump

    Before starting to install the engine, make sure it has a thermal safety valve (bypass valve) installed. Some pumps do not have this valve installed, so you may need to reuse the old pump or replace it with a new one.

    When you are ready to install, simply spde the pump onto the crankshaft and tighten the bolts. Then, you can continue to install the plastic case and the removed parts.

Frequently asked questions about high-pressure cleaning pumps

Who makes the best pressure washer pump?

High-pressure cleaning pump is not a very complicated equipment, so if you choose the right type, any pump can work normally. Of course, you should get one made of high-quality materials.

For brands, we recommend that you always use the same brand as the one your manufacturer uses. Original parts are always the safest choice because they are 100% compatible with your machine. However, this is not always possible. If your pressure washer manufacturer does not provide replacement parts, you can use a universal pump.

How long should the high-pressure cleaning pump be used?

The life of a high-pressure washer pump mainly depends on the type of pump. In addition to the output pressure, the durability of the pump is also reflected in its price. Therefore, the three-cylinder pump has the longest service life, and the axial pump has a longer service life than the wobble plate pump. When it comes to a specific number of working hours, you should look up the manufacturer’s specifications in the specific model’s user manual. However, to give you a general impression, the swash plate pump can be used for up to 500 hours, and the axial pump can be used for up to 900 hours. The working time of the three-cylinder pump is almost unlimited, but regular maintenance is required after every 1000-1500 hours of work.

Can I repair my high pressure washer pump instead of replacing it?

If your high pressure washer uses a swing pump or an axial flow pump, sadly, there is no choice but to replace the pump-once it runs out, it runs out. This is why you should make sure that the pump is indeed the problem, not the motor or other smaller parts of the pressure washer.

However, if you invest in a three-cylinder pump, you will most likely be able to open it and perform repairs. In fact, you can buy each part of a three-cylinder pump and replace it individually, without having to buy a brand new pump. This is why the upfront cost of a three-cylinder pump is much higher.

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