What Would Cause a Pressure Washer to Leak Oil? 6 Common Culprits

Imagine you have pressure washing on your to-do list, but when you go to grab the machine from storage, you notice an oil leak under the body of the pressure washer. So much for those weekend DIY plans. So, what would cause a pressure washer to leak oil in the first place? There are several potential causes behind a leaking pressure washer. Here’s what you should check for.

1. Cracked O-Rings and Connectors

One big enemy to successful pressure washing is dry or cracked O-rings and connectors. Pressure washers have several O-rings, seals, and other connectors to prevent water leaks and keep the machine running smoothly. However, these seals can become brittle and crack, and they’re prone to corrosion. If a seal breaks, it can cause both oil and water to leak from the machine.

If you’re handy, you can buy new O-rings and seals online or at a hardware store and replace them yourself. Otherwise, leave this job to a pro to prevent further oil leaks or extensive damage.

2. Damaged Piston Seals

Pistons are located inside the pressure washer’s pump, and they pressurize the water. Pistons have tightly fitting seals, but these seals wear down over time. If even one seal breaks, it can cause water or oil to leak and can cause a drop in water pressure. Watch for oil leaks around the pump or changes to the water pressure to identify a damaged piston seal, which you should replace as soon as possible.

3. Loose Pump Assembly Fittings

The pump assembly allows the water to flow and become pressurized for deep-cleaning grime off of hard surfaces. This assembly has multiple fittings to prevent water and oil leaks. If you notice oil leaking from the pressure washer pump, it may be a loose or damaged fitting. Tighten any loose fittings or replace broken fittings to stop the oil leak.

4. Faulty Drain Plug

If you don’t firmly secure the drain plug after replacing the oil, this can cause that fresh, new oil to leak. Make sure to tighten the drain plug after replacing the oil. If the plug is damaged, replace it to avoid ongoing oil leaks.

5. Dirty Dipstick

The dipstick is what you use to check the oil level on the pressure washer. Because you should be checking the oil level of the pressure washer before each use, the dipstick can be exposed to little bits of dirt and debris. If there’s buildup or a piece of debris on the dipstick, it can keep it from securing tightly into the reservoir.

Pull out the dipstick and check for any debris. Clean it and replace it. Check the O-ring around the dipstick opening and replace it if needed.

6. Old Pump

Old pressure washer pumps can wear out and cause an oil leak. If you notice oil or water leaking and issues with your pressure washer not starting, it may simply be time for a new pressure washer.

Most pressure washers last for 500 hours of use or around 10 years with light to moderate use and regular pressure washer maintenance. If your pressure washer is nearing those limits, or repairs cost more than half of what a new pressure washer would cost, upgrade to a newer model. New pressure washers cost $100 to $1,000, depending on the model.

What to Do if Your Pressure Washer Leaks Oil

Unless the oil leak is from a loose nut or bolt that you can tighten yourself or a seal that’s easy to replace, leave any oil leaks to a pro. Otherwise, you risk damaging your machine, and then you’d have to pay for the cost of a new pressure washer. Oil leaks can also leave pesky stains in your garage and even run off into your prized gardens or lawn if the oil mixes with water in your pressure washer.

By trusting these repairs to a power washing pro near you, the experts can find the source of the leak and patch things up quickly. This means you'll get back to cleaning up your property lickety-split. Whether you DIY or hire a pro for pressure washer repairs, make sure to check the oil level and refill it after repairs and before you use the pressure washer again to avoid disrupting your cleaning jobs.