To winterize a pressure washer, run the detergent out of the system, purge every drop of water from the pump with pump saver or RV antifreeze, drain the hoses, gun and wand, then store the machine where it stays above freezing. The job takes about fifteen minutes. Learning how to winterize a pressure washer properly is what stands between an easy April start and a cracked pump head that costs many times the price of a small bottle of antifreeze.
Around Barrie and Concord the window is shorter than most people expect. Environment and Climate Change Canada puts the average date of the first fall frost near Barrie at October 5 in its 1991 to 2020 climate normals, and in the earliest one year in ten it lands by September 23. We see the damage every spring at the counter, and it is nearly always the same story. One cold night in October, on a machine somebody meant to get to next weekend.
When should you winterize a pressure washer in Ontario?
Winterize a pressure washer before the first night that dips to zero, which for most of our customers means the last week of September. Waiting for the forecast to say freezing is cutting it fine, because the damage happens on the first cold night and there is no warning sound when it does.
Environment and Climate Change Canada publishes the odds by date, and they climb quickly through the end of September. The chart below reads the 1991 to 2020 normals for the Egbert station, the closest long record to Barrie.
Chance the first freezing night has already happened, Barrie area
By October 5, the published average50%
Read that as a deadline. By September 23 one year in ten has already had its first freeze, by October 5 it is a coin toss, and by October 19 it has happened in nine years out of ten. Anything still holding water on those dates is running on luck. The safe read for most of Simcoe County is to winterize a pressure washer in the last week of September and stop watching the forecast.
Concord and the rest of Vaughan get a little more room. The same source puts the average first fall frost at Toronto Pearson two weeks later, on October 20, though the earliest ten percent of years still bite by September 22. If you run machines at both ends of Highway 400, work to the Barrie date and you cover both yards.
| Measure | Barrie area (Egbert) | Concord area (Toronto Pearson) |
|---|
| Average date of first fall frost | October 5 | October 20 |
| Earliest one year in ten, first freeze by | September 23 | September 22 |
| Frost free days per year | 141 | 174 |
| Normal overnight low, October | 4.1 C | 5.3 C |
| Normal overnight low, November | -1.1 C | 0.2 C |
Can a pressure washer freeze and crack from one night?
Yes, and one night is all it takes. Water expands as it turns to ice, and the water sitting in a pressure washer has nowhere to go. The pump manifold, the unloader, the check valves and the quick connects are all closed volumes once the machine is shut down, so the ice pushes outward against cast aluminium and brass until something gives.
That is why we tell people to pick a date to winterize a pressure washer and work to it. The failure is rarely dramatic. Most of the machines that come across our service counter in April look perfectly fine. They start, they build a bit of pressure, and then water weeps from a hairline crack in the pump head or dribbles past a split o ring. By then the repair is a manifold or a full pump, and on a commercial unit that is the most expensive thing on the machine after the engine.
Three parts fail most often, and they fail in this order. The pump manifold cracks because it holds the largest trapped volume. The unloader valve seizes or splits, which is why we keep replacements on the shelf and wrote a separate guide on how the unloader valve works and when to replace it. The quick connect couplers ice up and the o rings tear the first time somebody forces a fitting in the spring.
How do I winterize a pressure washer, step by step?
Here is the sequence we follow to winterize a pressure washer in the Barrie and Concord service bays every fall. Do it in this order, because each step sets up the one after it. The machine needs to be running for parts of this, so work outside or with the bay door open.
Seven steps to winterize a pressure washer
Step 1
Flush the detergent. Draw clean water through the soap injector for two minutes until the line runs clear, so nothing is left to gum up over the winter.
Step 2
Sort out the engine. Top the tank up and add fuel stabiliser, run it for two minutes so treated fuel reaches the carburettor, then change the oil while it is still warm.
Step 3
Relieve the pressure. Shut the engine down, then squeeze the trigger until the gun stops spitting and the wand goes quiet.
Step 4
Disconnect and drain. Pull the garden hose and the high pressure hose, then walk each one out straight so the water runs off. Drain the gun and the wand separately.
Step 5
Pull the water out of the pump. Give the starter two or three slow pulls with the ignition off. Water will spit from the inlet and outlet ports until it stops.
Step 6
Charge the pump with antifreeze. Thread pump saver into the inlet and squeeze until it runs clean out of the outlet. This is the step that actually protects the manifold.
Step 7
Store it dry and covered. Coil the hoses loosely, cap the quick connects, and keep the machine off a bare concrete floor.
Flushing the detergent out of the injector
Detergent left in the injector line dries into a crust that blocks the check ball, and you will find out in the spring when the machine draws no soap at all. Two minutes of clean water through the injector at low pressure clears it. Holding the trigger open with the engine stopped also unloads the spring in the unloader, which is worth doing on any machine that sits for months.
Fuel and oil on a gas machine
Untreated gasoline starts to gum up in a few months, and a Honda GX or a similar small engine will crank all day in April without catching because the carburettor jets are varnished. Fill the tank close to full, which leaves less room for condensation, add stabiliser at the dose on the bottle, and run the engine for two minutes so treated fuel actually reaches the bowl. Change the oil the same afternoon while the engine is warm and the old oil carries the debris out with it.Relieving the pressure and clearing the pump
Once that is done, shut the engine off and pull the trigger. Draining the hoses is the easy part. The water that breaks pumps is the water trapped in the manifold, and gravity alone will not shift it. With the fuel off and the ignition off, pull the recoil slowly two or three times. The pistons act as a hand pump and push the water out through the ports. Keep going until nothing more comes out, then move straight to the antifreeze while the ports are still open. The people who winterize a pressure washer and still lose the pump in the spring have nearly always skipped this step.
Cap the quick connects afterwards so grit cannot get into the fittings over the winter. If yours are worn or leaking, sort them before storage instead of in April, and check the quick connect sizes and standards so you order the right ones.
Pump saver or RV antifreeze: which one should you use?
Use pump saver if you have it, and use RV antifreeze if you do not. Either one does the core job when you winterize a pressure washer, which is keeping the manifold from splitting. Pump saver does a second job that matters on a machine you rely on, because it carries a lubricant and a seal conditioner that keep the pump seals from drying out and shrinking over five idle months.
Pump saver comes in a small bottle with a threaded fitting that screws straight into the pump inlet, so you squeeze it in by hand and watch for it to come out the other side clean. RV antifreeze needs a short length of garden hose, a funnel and gravity, or a few pulls on the recoil to draw it through. Never use automotive engine antifreeze. It is ethylene glycol, it is toxic, and it goes on to contaminate whatever you wash next spring.
The mistake we see most is people putting antifreeze into a pump that still holds water. It dilutes to the point where it no longer protects, and the machine cracks anyway. Get the water out first with the recoil pulls in step 4, then charge the pump.
Can a pressure washer freeze in an unheated garage or a trailer?
Yes. An unheated garage in Barrie tracks within a few degrees of the outside air, and a steel trailer or a service body is worse, because it loses heat faster than it gains any. The November overnight normal at the Egbert station is minus 1.1 degrees, so an unheated space is below freezing on a typical November night whatever the daytime felt like.
Two situations catch people out. The first is the machine that lives on a truck and gets used through the fall, where every trip home is a night at ambient. Purge and charge that pump after the last wash of each cold day, because it is a five minute job that beats a spring rebuild. The second is a heated shop that gets its heat shut off over the holidays, which is a common one in industrial buildings around Concord. In both cases the safe move is to winterize a pressure washer as though it were going to sit outside.
If the machine genuinely lives somewhere that holds above freezing all winter, you can skip the antifreeze. Still drain the water and treat the fuel, because stale gasoline and dried seals do their damage regardless of temperature.
What to do if your pressure washer already froze
Bring it somewhere warm and let it thaw completely before you try to start it. Turning over a pump full of ice is what turns a survivable freeze into a broken manifold, because the pistons have nowhere to move.
Once it has thawed, connect water and run it at low pressure with the gun open, and watch the pump head and the fittings closely. Weeping at the manifold seam, a drop forming on the casting itself instead of at a joint, or pressure that builds and then falls away all point to a crack. Seals and o rings are a straightforward fix, and we do those over the counter. A cracked casting means a new manifold or a new pump, and it is worth reading the signs that a pump needs service before you spend money on parts that will not solve it.
Bring the whole machine in if you are unsure. We would sooner spend ten minutes diagnosing it on the bench than have you order a manifold for a pump that only needed an unloader.
Hot water machines need more than the pump drained
A hot water unit has a heating coil, a float tank and a burner circuit, and every one of them holds water. The coil is the expensive part. It is a long run of steel tubing with no drain point at the bottom, so the only way to protect it is to push antifreeze through the whole circuit until it comes out of the wand.
The float tank empties through its own drain plug, and the fuel filter and the burner nozzle both want checking before the machine sits. If you run a hot water machine on a wash pad through the winter, the coil is the reason we push people toward a heated enclosure or an indoor bay. Our hot water pressure washers and cold water pressure washers pages set out which machines suit an outdoor pad, and there is more detail in our comparison of hot water against cold water units.
Whichever type you run, book the coil flush at the same time you winterize a pressure washer for the season. Doing both in one visit means the machine comes back once and goes away ready.
Frequently asked questions
How long does it take to winterize a pressure washer?
About fifteen minutes for a cold water machine once you have the pump saver and the stabiliser in front of you, and closer to half an hour for a hot water unit because of the coil and the float tank. The oil change adds another fifteen minutes.
Can I winterize a pressure washer with RV antifreeze instead of pump saver?
Yes. RV antifreeze is propylene glycol, it is safe around potable water lines, and it will stop the manifold splitting. Pump saver is the better choice on a machine you depend on because it also lubricates and conditions the seals. Automotive engine antifreeze is never an option, since it is toxic.
Do I need to winterize a pressure washer that lives in a heated shop?
Skip the antifreeze if the shop reliably holds above freezing all winter, including over the holiday shutdown. Still drain the water, treat the fuel and change the oil. Fuel varnish and dried pump seals ruin a spring start just as effectively as ice does.
How do I winterize a pressure washer that stays on a service truck?
Treat every cold night as winter. Purge the pump and charge it with pump saver at the end of each day once overnight lows are near zero, then flush the antifreeze through at the start of the next job. It takes five minutes at each end and it is the only thing that reliably protects a machine that sleeps outdoors.
Will winterizing repair a pump that already froze?
No. Antifreeze prevents damage and does nothing to reverse it. If the pump has already cracked, the manifold or the pump itself needs replacing, and a proper diagnosis first will tell you which. Thaw the machine fully before you turn it over, because cranking a frozen pump usually makes the damage worse.
Should I run the machine before storing it for winter?
Run it during the process, before you charge the pump. The last thing that goes through the pump should be antifreeze, so any run after that pushes it out and leaves you back where you started. Two minutes of running on treated fuel comes before you charge the pump, which is why the order in the seven steps matters.
If you would sooner hand the fall shutdown to people who do it every day, book your machine into our Barrie or Concord service bay before the first freeze. We winterize a pressure washer properly: flush and purge, charge the pump, change the oil, and replace the unloaders, seals and couplers that are already weeping so they are not a surprise in April. Call Barrie at 249-315-4673 or Concord at 905-760-1711, or drop the machine at the counter and we will look at it while you wait. Hours and directions for both branches are on our Barrie location page.
