How to Winterize a Pressure Washer

Give your machine everything it needs to withstand freezing temperatures

high pressure cleaner on the terrace
Photo: SimonSkafar / E+ / Getty Images
high pressure cleaner on the terrace
Photo: SimonSkafar / E+ / Getty Images
SKILL LEVEL
Easy
COMPLETION TIME
30 minutes
COST
$25–$50
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What you'll need:
TOOLS
  • Antifreeze and coolant
  • Fuel stabilizer
  • Synthetic motor oil
SUPPLIES
  • Large funnel
  • Oil funnel
  • Two- to three-foot garden hose
  • Two or three catching receptacles
  • Siphon pump

Along with your house, your yard, and everything in between, your pressure washer also needs some TLC before winter sets in. Without proper preparation, a power tool like this can become damaged in more ways than one from extremely cold temperatures. The following guide will show you exactly how to winterize your pressure washer so you have even more knowledge about how to use a pressure washer under your belt.  

Prepping to Winterize a Pressure Washer

Pressure washer cleaning machine on wet concrete
Photo: Irina Shatilova / iStock / Getty Images

There isn’t a lot you need to do to prepare for a task like this other than gathering all the necessary tools and materials. Once you have them ready to go, set the machine up in a well-ventilated space (ideally outdoors) to protect yourself from the VOCs (volatile organic compounds) that the necessary chemicals may release. 

Along with how to prep your pressure washer for storage, knowing which things you should or shouldn’t pressure wash will also prevent unnecessary damage.

  1. Empty and Stabilize Fuel Container

    If your pressure washer is gas powered, start the winterization process by emptying and stabilizing the gas container. Skip this step if your machine is electric. 

    Locate and turn off the fuel shutoff valve. If your machine doesn’t have one, you’ll need to use a siphon to manually empty the fuel into a metal receptacle. Then start the machine and run it for several minutes to use up the remaining gas. 

    Next, remove the cap from the gas tank and add two capfuls of fuel stabilizer. Seal it back up and move on to the following step.

  2. Drain and Refresh Oil

    While it’s not always necessary to refill your pressure washer’s oil tank before winter (especially if you’ve already done it recently), doing so will ensure it’s ready to use and in great shape by the time warmer weather rolls around. And if your machine is in good working order, you can expect the cost to pressure wash your house to go down, too. 

    Find and open the oil drain plug using a socket wrench, then use a metal receptacle to catch the oil as it drains out. It can take upwards of 10 minutes for the oil to drain completely, so be prepared to wait a bit. 

    Once drained, seal the oil drain plug and place a gas funnel into the fill-up port. Pour synthetic motor oil into the funnel until the oil tank is completely filled, checking the levels periodically to avoid overspill.

  3. Remove the Battery From Electrically-Powered Pressure Washers

    There’s nothing worse than attempting to start up your electric pressure washer come spring only to discover that its battery is somehow drained. Avoid this problem entirely by simply removing or disconnecting the battery before storing it for winter.

  4. Clean Filters, Nozzles, and Exterior

    Washing up all the bits and bobs of your pressure washer before storing will also prevent it from deteriorating in the winter. Remove the filters and nozzles, and use a toothbrush and straw scrubber or fine needle to get rid of any dirt blockages. Store them separately from your machine, ideally in a closed container where they won’t attract any dust or pests.

  5. Rinse the Pump With Antifreeze

    Locate the inlet fitting on your machine’s water pump, remove the cap, and attach a two- to three-foot garden hose. Fit the large funnel onto the other end of the garden hose and pour in enough antifreeze to fill it up halfway. 

    Locate the water pump outlet fitting, open it, and place a metal or plastic receptacle near the opening to catch the pour-over. Pull the water pump cord to fully circulate the antifreeze and stop when the water leaving the outlet is no longer clear but pink. Seal both inlet and outlet, then remove and dry tools.

  6. Store Somewhere Dry

    Once you’ve taken all these steps, you can safely store your machine in both cold and warm conditions. Just make sure that it won’t be exposed to any moisture to prevent rust from forming.

DIY vs. Hire a Pro

It’s unlikely that a local pressure washer will come by just to put your machine away for the winter, but it’s possible that a pro will add this task to another service for an additional fee. In most cases, this is a great chance to DIY and learn more about caring for your pressure washer at the same time.

Frequently Asked Questions

Whether or not you need to winterize your pressure washer will largely depend on where you’re able to store it. For example, if you have somewhere relatively warm to keep it, you won’t need to fill the water pump with antifreeze because there will be no risk of freezing in the first place. However, emptying the gas chamber and refreshing the oil is good to do beforehand, regardless of what storage conditions are available to you.

If pressure washers are stored in freezing conditions and aren’t pretreated for such temps, any liquid remaining in the water pump may freeze, expand, and severely damage your machine. While often recommended, emptying the machine with compressed air is a long and tedious process and still may not completely drain the liquid in this pressure washer part. But adding a bit of antifreeze instead will keep it in tip-top shape without the extra effort.

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