Pressure washers get abused. They sit for months, get dragged across driveways, and are expected to fire up instantly when you need to clean the deck or wash the car. A little maintenance goes a long way — here's what to do and when to do it.
After Every Use
1. Flush the Pump
If you used any chemicals or detergent, run clean water through the pump for 1–2 minutes to flush out residue. Chemicals left in the pump corrode the internal seals and valves.
2. Relieve Pressure Before Disconnecting
Squeeze the spray gun trigger to release water pressure before disconnecting the hose or turning off the engine. This prevents pressure spikes that can damage the pump.
3. Disconnect and Drain
Disconnect the garden hose, spray gun, and wand. Drain any remaining water from the pump by pulling the recoil start cord a few times (with the engine off and spark plug disconnected). Water left in the pump freezes and cracks the housing.
Every 25 Hours or Once per Season
1. Change the Pump Oil
Many homeowners don't realize pressure washer pumps have their own oil — separate from the engine oil. Check your manual for the pump oil change interval (typically every 50 hours for gear-driven pumps, or "non-serviceable" for some axial cam pumps).
To change pump oil:
- Locate the pump oil drain plug (usually on the bottom of the pump)
- Drain the old oil into a container
- Refill with the recommended pump oil (typically SAE 30 non-detergent or a specific pump oil)
- Do not overfill — check the sight glass or dipstick
2. Change the Engine Oil
Gas pressure washers have a small engine with its own oil. Change the engine oil after the first 5 hours of use (break-in), then every 50 hours or once per season. Use the oil weight specified in your manual.
3. Clean or Replace the Air Filter
A dirty air filter reduces engine power and causes the pressure washer to run rough. Clean a foam filter with soapy water, let it dry, and re-oil it. Replace a paper filter when it's visibly dirty.
4. Check the Spark Plug
Remove and inspect the spark plug. Clean or replace as needed. Check the gap (typically 0.030"). A fouled spark plug causes hard starting and rough running.
Before Storage (Winterizing)
1. Add Fuel Stabilizer
Add fuel stabilizer to a full tank and run the engine for 5 minutes so treated fuel flows through the carburetor. This prevents the carburetor from clogging during storage — the most common pressure washer problem I see.
2. Use Pump Saver
For gas pressure washers, use a pump saver antifreeze treatment (like Briggs & Stratton Pump Saver). This is a can of pressurized antifreeze and lubricant that you screw into the water inlet. It:
- Prevents water from freezing and cracking the pump
- Lubricates the internal seals so they don't dry out
- Protects against corrosion
This is critical if you store your pressure washer in an unheated garage or shed.
3. Store Properly
Store the pressure washer in a dry location, upright, with the hose coiled (not kinked). Disconnect the spray gun and wand to prevent damage.
Common Problems Prevented by Maintenance
Won't start after storage: Almost always stale fuel. Use stabilizer or drain the tank before storing.
Low pressure or surging: Usually a clogged nozzle, dirty inlet screen, or worn pump valves. Clean the nozzle with the included wire tool, check the inlet screen, and inspect the pump if the problem persists.
Water leaking from the pump: Worn seals. If you see water dripping from the pump body (not the hose connections), the seals need replacement.
Engine runs rough: Dirty air filter, old spark plug, or stale fuel. Start with the simplest fix — fresh fuel and a clean air filter.
The Bottom Line
Pressure washer maintenance is simple: flush chemicals after use, change the oil regularly, use fuel stabilizer before storage, and protect the pump with pump saver. Do these four things and your pressure washer will start reliably and deliver full pressure for years.