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Pressure washer storage in the garage: the pump decides where and how it sits

Storage systems · 6 min read

Moving a pressure washer into the garage is not winterizing it. An unheated garage in January sits below freezing for weeks at a time, and a pump holding even a little water is exposed the whole while. The Briggs and Stratton operator’s manual puts the stakes in a boxed notice: protect the unit from freezing temperatures, because failure to do so will permanently damage the pump and render the unit inoperable, and freeze damage is not covered under warranty (s1). The garage is the right place for the machine. It is the treatment, done before the machine is parked, that makes the garage safe.

Job summary

Difficulty: low. This is draining, flushing, and treating, not disassembly. Time: about half an hour of active work for a gas unit, less for an electric one. The 30-day line: the manufacturers draw it clearly, a washer that will sit unused for more than 30 days needs the full storage preparation for engine and pump, gas or electric (s1, s2). Shorter gaps between uses need only the after use drain routine. Hire-a-pro line: a pump that already leaks, pulses, or has lost pressure goes to a service centre before storage. Winterizing a damaged pump preserves the damage.

Tools and materials

Storing a pressure washer in the garage, step by step

  1. Flush the detergent out first. Run clean water through the washer for 1 to 2 minutes and pull the trigger until the output runs clear. Detergent left in the system all winter is residue the pump did not need (s4). On a unit with a cleaning tank, empty it by running the washer with the black spray tip until the tank is empty (s1).
  2. Disconnect everything and drain it. Remove the garden hose, the high pressure hose, and the spray gun. Let all the water drain completely. The Greenworks storage guidance is blunt about why: even a small amount of water left in the lines can cause damage if it freezes (s3).
  3. Clear the pump. Run the washer for a few seconds with no hose attached to push the remaining water out of the pump (s3). Short bursts only. The point is to empty it, not to run it dry.
  4. Treat the pump with pump saver. With the unit off and disconnected from the water supply, connect the pump saver bottle to the pump inlet and squeeze until the product exits through the outlet (s3). That visible exit is the check: the treatment has displaced the leftover water and coated the inside of the pump, which is what prevents freezing and corrosion damage and lubricates the pistons and seals (s1, s3).
  5. Handle the fuel on a gas unit. Add fuel stabilizer and run the engine for a couple of minutes so treated fuel circulates, or drain the tank and run the engine until it stops (s3). The reasoning is Generac’s: fuel stored over 30 days can go bad and damage fuel system components, and fuel should not be carried from one season to the next untreated (s2). Shut the fuel valve when the engine work is done (s4).
  6. Oil the cylinder on a gas unit that will sit all winter. Pour a tablespoon (5 to 10 cc) of clean engine oil into the cylinder, or spray in a suitable fogging agent, per Generac’s long term storage procedure (s2).
  7. Drain and store the accessories with the unit. The high pressure hose, gun, wand, and nozzles get drained and kept in a dry place. Coil the hose loosely. A kinked or tightly coiled hose weakens its lining over time (s4).
  8. Let the unit cool fully, then cover it. Never put a storage cover over a hot pressure washer, and choose a cover that does not retain moisture (s1, s2).

The pump saver fallback the manuals document

If pump saver is not on the shelf, the manuals do not tell you to skip the step. They give a substitute procedure, and it is specific. Connect a 3-foot (1 m) section of garden hose to the water inlet adapter. Pour RV antifreeze, the alcohol free kind, into the hose. Pull the recoil handle twice, which draws the antifreeze through the pump. Disconnect the hose (s1). Generac’s support documentation carries the same fallback for its Pump Shield product (s2). Two pulls, not a long cranking session: the antifreeze needs to fill the pump, and the procedure is measured in pulls because that is what moves it through.

One caution from the manual pages: pump saver drips from the pump after treatment and will stain wood and concrete (s6). Do the treatment over a drip tray or a piece of cardboard, not over the finished floor.

Where it sits until spring

The storage spot has three requirements, and all three come from the manufacturers rather than from tidiness. First, clean and dry: every manual in the packet lands on storing the unit in a clean, dry area (s1, s2). Second, off the concrete. Greenworks advises against placing the unit directly on the floor because moisture builds up there, and recommends elevating it on a piece of wood or a shelf (s3). Third, away from heat and ignition sources, which Generac states as a standing rule for washers and their fuel (s2). A gas unit parked beside the furnace fails that rule even in a clean, dry garage.

Note what is not on the list: outdoors under a cover. Greenworks advises against it directly, because exposure to freezing temperatures can damage the pump even under a cover (s3). The treated pump in the garage is the system. The cover alone is not.

What success looks like in April

Success is verifiable at the first hookup. The pump saver or antifreeze that went in last fall flushes out in the first seconds of flow. The unit builds full pressure with no pulsing and no leaks at the pump body. The engine, if it is a gas unit, starts on treated fuel or a fresh tank rather than on last season’s untreated gasoline. And nothing about the first wash of the year involves pricing a replacement pump, which is the spring bill the fall half hour exists to prevent.

, Tom Reilly, Home & DIY Writer