This is the most important page in this hub. Water left inside a pump freezes, expands and cracks the housing, and a cracked pump generally costs more than the machine is worth. It kills more pressure washers than use does, and it takes about a minute to prevent.
Why water in a pump is so destructive
Water expands as it freezes, and a pump is a sealed assembly of close-tolerance metal parts with nowhere for the expansion to go. The result is a cracked housing, a split valve seat or a burst seal, and on a consumer machine none of those is economically repairable.
It does not need a hard winter. A single night below freezing with water sitting in the pump is enough, which is why the job is done in autumn rather than in January.
The one-minute procedure (any machine)
- Run detergent out. Pickup tube in clean water, black soap tip fitted, run thirty seconds.
- Turn the water off, then run the remaining water out. Squeeze the trigger with the machine running until it spits rather than streams, then shut the machine off immediately — do not keep it running dry.
- Disconnect everything and drain the high-pressure hose and the garden hose.
- Push pump saver through the pump. Screw the bottle onto the water inlet and squeeze until you see it come out of the outlet. That displaces the remaining water and leaves antifreeze and lubricant in its place.
- Store it somewhere it will not freeze if you can. With pump saver in, an unheated garage is fine; a sheltered spot is better than the open.
That is the whole job. One bottle of pump saver covers several machines, which makes it look expensive for one and makes it the cheapest insurance on this site.
Gas machines: three extras
Fuel. Either run the tank dry, or fill it and add stabilizer. The worst option is a half-full tank of untreated petrol, which is both stale and condensing moisture. Stale fuel is the number one reason a gas machine will not start in spring — won’t start.
Engine oil. If it is due, change it now rather than in spring. Fresh oil sitting over winter is better than used oil, which holds acids and moisture.
Pump oil. If your pump has a dipstick or a fill plug, check it — which oil and when. Most consumer pumps are sealed and have none.
If you do not have pump saver
The usual improvisation is RV or marine antifreeze (propylene glycol) drawn through the pump by running the machine briefly with the inlet in a container of it. It is less convenient and it works.
Never use automotive ethylene glycol antifreeze. It is toxic, you will be flushing it onto your drive in spring, and it is not formulated for pump seals.
Compressed air through the pump is sometimes suggested and is a poor substitute: it rarely clears everything, and it leaves no lubricant behind.
Spring restart
- Connect the water and flush the pump saver out before the first use — run water through with the trigger open for thirty seconds.
- Check the inlet filter and rinse it.
- Check the hose for perishing, cracks or bulges after a cold winter.
- Purge the air properly before starting the motor, per the setup sequence.
- Gas: fresh fuel, check the oil, check the air filter.
The honest summary
Everything else in the maintenance checklist is good practice. This one is the difference between a machine that lasts two seasons and one that lasts ten, and it is one bottle and one minute.
