How to Winterize Simpson Pressure Washer? Storage Advice

Introduction

Winterizing a Simpson pressure washer is essential for protecting the pump, engine, and accessories from freeze damage during cold months. When water remains inside the system, it expands as it freezes, cracking seals, warping metal components, and potentially ruining the entire unit. This guide explains how to winterize Simpson pressure washer equipment step by step, covering everything from draining fluids to adding antifreeze and storing the machine safely. Whether you own a gas‑powered or electric model, the principles remain the same: remove all water, protect internal parts, and store the washer in a dry, temperature‑controlled environment.

Table of Contents

• Why Winterizing Matters
• Tools and Materials Needed
• Preparing the Pressure Washer
• Draining the Pump and Hoses
• Adding Antifreeze
• Protecting the Engine
• Storing the Unit
• Step‑by‑Step Winterization Guide
• Comparison Table: Simpson Models Winterization Requirements
• Tips and Best Practices
• Common Mistakes to Avoid
• Frequently Asked Questions
• Conclusion

Why Winterizing Matters

Freezing temperatures cause water to expand by roughly nine percent. Inside a pressure washer, that expansion exerts tremendous force on pump pistons, seals, valves, and the hose assembly. Even a small amount of residual water can crack a ceramic piston or split a high‑pressure hose, leading to costly repairs or complete replacement. Moreover, gasoline left in a carburetor can gum up, and oil can thicken, making spring startup difficult. Proper winterization eliminates these risks, extends the service life of the machine, and ensures it is ready for immediate use when the weather warms.

Tools and Materials Needed

Before beginning, gather the following items to make the process smooth and safe:

• Owner’s manual for your specific Simpson model
• Adjustable wrench or socket set for drain plugs
• Bucket or large container to catch drained fluids
• Non‑toxic RV/marine antifreeze (propylene glycol based)
• Fuel stabilizer (for gas models)
• Clean rags and shop towels
• Protective gloves and safety glasses
• Plastic sheeting or a breathable cover for storage

Having everything on hand prevents interruptions and reduces the chance of forgetting a critical step.

Preparing the Pressure Washer

Start by moving the pressure washer to a well‑ventilated, level surface outdoors or in a garage with the door open. Turn off the fuel valve (if equipped) and disconnect the spark plug wire to prevent accidental starts. Remove any attachments such as nozzles, surface cleaners, or detergent tanks. Rinse the exterior with a garden hose to wash away dirt, debris, and chemical residues that could corrode metal parts during storage. Allow the unit to dry completely before proceeding.

Draining the Pump and Hoses

Locate the pump drain plug, usually found on the bottom of the pump housing. Place a bucket beneath it, remove the plug with the appropriate wrench, and let all water flow out. Next, disconnect the high‑pressure hose from the pump outlet and the spray gun. Hold the hose vertically to let gravity pull out remaining water. If your model has a low‑pressure inlet hose, detach it and drain it as well. For units with a built‑in detergent siphon tube, remove the tube and blow out any trapped liquid using low‑pressure compressed air. Replace the drain plug once the pump is empty.

Adding Antifreeze

Propylene glycol antifreeze is safe for pump seals and environmentally friendly. Pour the recommended amount (typically one quart for most Simpson residential models) into the pump inlet. Reattach the inlet hose, then briefly run the engine (or motor) for 10‑15 seconds with the trigger gun open to circulate the antifreeze through the pump, hose, and gun. Shut the engine off immediately. This coats internal surfaces with a protective film that prevents any residual moisture from freezing. Do not use automotive ethylene glycol antifreeze, as it can damage pump components and is toxic.

Protecting the Engine

For gas‑powered Simpson washers, add a fuel stabilizer to the tank according to the product instructions, then run the engine for a few minutes to distribute the treated fuel through the carburetor. Turn off the fuel valve and let the engine run until it stalls, clearing the carburetor of untreated gasoline. Change the engine oil if it is due for service; fresh oil provides better corrosion protection during storage. Remove the spark plug, pour a teaspoon of clean engine oil into the cylinder, pull the recoil starter a few times to distribute the oil, then reinstall the spark plug (hand‑tight only). This fogging step coats the cylinder walls and piston rings.

Storing the Unit

Choose a dry, frost‑free location such as a heated garage, basement, or insulated shed. Place the pressure washer on a pallet or wooden blocks to keep it off a cold concrete floor. Cover the machine with a breathable fabric cover or a loose plastic sheet that allows air circulation; avoid sealing it tightly, which can trap moisture. Store hoses, nozzles, and accessories in a separate container to prevent kinks and loss. If you must store the unit outdoors, elevate it on a platform, cover it with a waterproof tarp, and secure the tarp against wind.

Step‑by‑Step Winterization Guide

1. Read the owner’s manual for model‑specific instructions and torque specifications.
2. Move the washer to a ventilated, level area; disconnect spark plug wire.
3. Remove all accessories and rinse the exterior; let dry.
4. Drain the pump via the bottom drain plug; collect water in a bucket.
5. Detach high‑pressure hose, spray gun, and inlet hose; drain each completely.
6. Blow out the detergent siphon tube with low‑pressure air if present.
7. Reinstall the pump drain plug securely.
8. Pour the recommended volume of propylene glycol antifreeze into the pump inlet.
9. Reconnect the inlet hose; start the engine (or motor) and run for 10‑15 seconds with the trigger open.
10. Shut off the engine; add fuel stabilizer to the gas tank and run until the engine stops.
11. Change engine oil if required; fog the cylinder with a teaspoon of oil via the spark plug hole.
12. Reinstall spark plug hand‑tight; reconnect spark plug wire.
13. Place the unit on a pallet in a dry, frost‑free space; cover with a breathable cover.
14. Store hoses and accessories separately in a labeled container.

Comparison Table: Simpson Models Winterization Requirements

Tips and Best Practices

• Always use propylene glycol antifreeze; it is non‑corrosive and safe for pump seals.
• Label the antifreeze container with the date and model to avoid accidental reuse of old fluid.
• Run the engine briefly after adding stabilizer to ensure treated fuel reaches the carburetor.
• Store the pressure washer upright; laying it on its side can cause oil to leak into the combustion chamber.
• Inspect hoses for cracks or wear before storage; replace damaged sections now rather than in spring.
• Keep a maintenance log noting the date of winterization, oil change, and any parts replaced.
• If you own multiple units, create a checklist for each model to standardize the process.

Common Mistakes to Avoid

One frequent error is skipping the antifreeze step and assuming that draining alone is sufficient. Even a few milliliters of water left in the pump can freeze and cause damage. Another mistake is using automotive ethylene glycol antifreeze, which attacks pump seals and poses a toxicity hazard. Forgetting to add fuel stabilizer leads to gummed carburetors and hard starts. Over‑tightening the spark plug after fogging can strip threads; hand‑tight is adequate. Finally, sealing the unit in an airtight plastic bag traps condensation, promoting rust on metal surfaces. Avoid these pitfalls by following the step‑by‑step guide and the tips above.

Frequently Asked Questions

How often should I winterize my Simpson pressure washer?

Winterize the unit once per year before the first hard freeze. If you live in a region with fluctuating temperatures, perform the procedure each fall and again after any unexpected cold snap.

Can I use regular automotive antifreeze instead of RV antifreeze?

No. Automotive antifreeze contains ethylene glycol and corrosion inhibitors that are not compatible with pressure washer pump seals. Use only non‑toxic propylene glycol RV or marine antifreeze.

Do electric Simpson models require fuel stabilizer?

Electric models have no gasoline engine, so fuel stabilizer is unnecessary. Focus on draining water, adding antifreeze, and protecting the motor from moisture.

What should I do if I forgot to drain the high‑pressure hose?

Disconnect the hose, hold it vertically, and allow gravity to drain any water. Then blow compressed air through the hose to remove residual moisture before adding antifreeze to the pump.

Is it safe to store the pressure washer outside under a tarp?

Outdoor storage is acceptable only if the unit is elevated off the ground, covered with a breathable waterproof tarp, and the area does not experience prolonged sub‑zero temperatures. Indoor, climate‑controlled storage is strongly preferred.

Conclusion

Properly winterizing your Simpson pressure washer protects the pump, engine, and accessories from freeze damage, corrosion, and fuel degradation. By following the detailed steps—draining all water, circulating propylene glycol antifreeze, stabilizing fuel, fogging the cylinder, and storing the unit in a dry, ventilated space—you ensure reliable performance when the cleaning season returns. Remember to consult your model’s manual for any unique requirements, keep a maintenance log, and avoid common mistakes such as using the wrong antifreeze or sealing the machine airtight. With these practices in place, your Simpson pressure washer will remain a dependable tool for years to come.