A gas pressure washer has two parts to winterize: the small engine and the water pump. The engine needs the same fuel and oil care as a mower. The pump needs to be drained and protected from freezing, because even a little trapped water can crack the pump housing or damage seals. Follow both the engine and pump sections of your manual.
Pump protection
- Disconnect hoses and the spray wand and drain them completely.
- Drain the pump by pulling the recoil a few times with the ignition off, per the manual.
- Use a pump protector or antifreeze made for pressure-washer pumps if the machine will be stored where it can freeze. Do not use automotive antifreeze unless the manual allows it.
- Check pump oil on pumps that have a separate crankcase, and change it at the interval the manual gives, using the type specified.
Winterizing and spring start-up checklist
- Treat the fuel with stabilizer and run the engine so it reaches the carburetor, or follow the manual’s run-dry instructions.
- Change the engine oil while it is warm so contaminants drain out with it.
- Drain and protect the pump, hoses and wand from freezing.
- Store it indoors where it stays above freezing if possible.
- In spring, check oil, connect the water supply and run water through the pump before starting the engine.
- Inspect hoses and O-rings for cracks before using pressure.
- Never start the pump dry or let it run long without spraying, which can overheat it.
Frequently asked questions
Can I store my pressure washer in an unheated shed?
Yes, if the pump is drained and protected with a pump protector made for freezing conditions, and the fuel is stabilized.
What oil goes in the pressure washer pump?
Pump oil requirements vary. Some pumps are sealed; others take a specific pump oil. Follow the pump section of the manual.
Why does my pressure washer pulse in spring?
Common causes include air in the supply line, a clogged inlet screen or nozzle, or a stuck valve. Run water through it first and check the screens.
AMSOIL products for this job
- AMSOIL Gasoline Stabilizer. AMSOIL says: “Helps keep fuel fresh up to 12 months”; “Eliminates the need to drain fuel from equipment before long-term storage”.
- AMSOIL 10W-30 100% Synthetic Small-Engine Oil. AMSOIL says: “Protects up to 200 hours”; “Prevents ring and valve sticking while helping eliminate carbon deposits”.
- AMSOIL MP Metal Protector. AMSOIL says: “Lubricates moving parts”; “Helps protect against rust and corrosion, even in salt water”.
AMSOIL does not list a pressure-washer pump protector; use one made for pumps and follow the label.
Product wording above is quoted or summarized from amsoil.com. Read each product’s label and data sheet for directions.
Use AMSOIL’s official lookup guide to see what is listed for your vehicle or equipment, then order online whenever it suits you.