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A man surfing the web for a replacement Power Pressure Washer Pump. A man surfing the web for a replacement Power Pressure Washer Pump.
How-To Installation Product & Troubleshooting Problems Pressure Power Washer and Pump Maintenance
July 23, 2021

PRESSURE POWER WASHER PUMPS - ALL YOU NEED TO KNOW TO FIND YOUR CORRECT REPLACEMENT

How to find the perfect replacement pump for your pressure washer

WRITTEN BY: KATE HUFFMAN

So you’re looking for a replacement pressure washer pump? Well, you’ve come to the right place. Match our extensive knowledge with our affordable prices and great selection, and you won’t find a better place to shop for a new pump. Use our fitment chart (which includes clickable links to all our pumps) at the bottom of the page combined with the following tips. You’ll have everything you need to find the perfect replacement.

Step 1: Engine Shaft Size and Orientation

First and foremost, remove your old pump and take a good look at the engine shaft. Put a micrometer on it and get an accurate measurement; don’t just eyeball it. This is the single most important part of making sure you get the correct replacement pump. Most pressure washer engines have a shaft measuring 3/4”, 7/8”, or 1” in diameter. Then take note of whether your engine is vertical or horizontal. In layman’s terms, a vertical engine’s shaft either points straight up or straight down, while a horizontal engine’s shaft points out to the side. Some replacement pumps can only be installed on a horizontal engine shaft due to an oil ventilation port, so double-check our chart before making your decision.

Step 2: Bolt Pattern

Next, measure the bolt pattern around the shaft, center-to-center. A few power washer models might have two or even three different bolt patterns around the engine shaft. The most common bolt patterns are;

(4 bolts) 2 9/16” square

(4 bolts) 2 5/8” square

(3 bolts) 7 11/16", 6 3/16", 6 7/16"

(4 bolts) 5 1/4", 3 1/4", 5 3/16", 4 1/2"

Keep in mind that if your bolt pattern does measure 2 9/16” square, a pump with a bolt pattern of 2 5/8” square will still work for you.

Also, if you have a vertical engine shaft and a three-bolt mounting pattern, note which direction your water inlet and outlet face. If they come out of the front of your washer, you’ll need a ‘front-facing’ replacement pump, and if they come out of the back of your washer, you’ll need ‘rear-facing’. Check our chart below to make sure you’re looking at pumps with the water connections oriented in the direction you’ll need.

Step 3: Engine Horsepower

Now that you know your engine shaft size, orientation, and bolt pattern, you should have an idea of which pumps are going to work for your model. Some models might have as many as six replacement pump options. But remember; some pumps might be too powerful for your engine to handle. If the maximum horsepower of your engine and a pump’s max PSI isn’t balanced, the pump can produce too much pressure for your engine to handle, causing it to bog down or even stall. Check your engine’s maximum horsepower rating, then compare it to our PSI chart below.

RUGGED U: HOW TO INSTALL THE ROP SHOP PRESSURE WASHER PUMP - INSTALLATION TIPS AND TRICKS RUGGED U: HOW TO INSTALL THE ROP SHOP PRESSURE WASHER PUMP - INSTALLATION TIPS AND TRICKS

6.5 HP = 3600 max PSI or less

6 HP = 3100 max PSI or less

5.5 HP = 2800 max PSI or less

5 HP = 2600 max PSI or less

4.5 HP = 2400 max PSI or less

For heavy-duty pressure washers, take a look at our chart below for more HP to PSI details. You can also watch this installation video that will help you through the process of uninstalling your old pump and installing your new pump on your pressure washer. Also, if you have problems with your pressure washer even after you replace your pump, please check out this helpful Rugged U video on troubleshooting Pressure Washer issues or our Rugged U blog about troubleshooting a pressure washer pump after installation.

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