Pumps & Unloader Valves
Pressure Washer Pump SJF-1807Q | 275 Bar 4000psi | 15L/min Brass Head
TBS-09006PWSP-00097
£635.99
Pumps & Unloader Valves
4 products available
A pressure washer pump is the heart of any pressure washer, and the unloader valve is the part that protects it. This category covers pressure washer replacement pumps, unloader valves and related pump parts for trade and industrial users who keep cleaning equipment running. Contractors, hire fleets, workshop maintenance teams and facilities crews all rely on these parts when a machine loses pressure, pulsates or stops delivering flow.
The range here is narrow and focused. Compel carries pumps and unloader valves for pressure washer repair, not a wide catalogue of every make and model. That means you can check the listing, confirm the fit, and order without sorting through unrelated stock. Always compare the pump or valve details on the product page against your machine's data plate before you buy. Matching the right part first time keeps downtime short and avoids returns.
4 products in Pumps & Unloader Valves
Products
Pumps & Unloader Valves
Unloader Valves Pressure Washer FJ0233 | 7.5KW Pump Head | Fine Thread
TBS-08998PWSP-00090
£52.99
Pumps & Unloader Valves
Pressure Washer Pump SJW14085 / SJW14075 | 19mm Shaft | 100bar Brass Head
TBS-08895PWSP-00052
£179.99
Pumps & Unloader Valves
Pressure Washer Pump Parts | Pump Head Assembly | K1 Series Fit | Ф60-6R
TBS-08769PWSP-00009
£111.99
Matching a pressure washer water pump to your machine
Start with the data plate on your pressure washer and the markings on the existing pump. A replacement pump has to suit the drive type, whether that's a petrol engine or an electric motor, and it has to match the machine's rated pressure and flow. Pumps are not interchangeable just because they look alike.
Check the shaft type, shaft size and mounting pattern on the listing against your old pump. A pump that mounts but runs at the wrong speed or load will wear fast or fail early.
- Drive: petrol engine or electric motor
- Rated pressure and flow of the original machine
- Shaft type, shaft size and mounting pattern
- Inlet and outlet port sizes and thread types
Choosing an unloader valve on a pressure washer
The unloader valve on a pressure washer controls what happens when you release the trigger. It diverts flow away from the outlet so the pump isn't dead-heading against a closed gun. A worn or stuck valve causes pressure drops, surging and hot, overworked pumps.
Pick a valve that matches the pump's flow and the machine's working pressure. Check the inlet and outlet connections, and note whether the valve has an adjustable pressure setting. Fixed and adjustable types suit different setups, so confirm which one your machine uses before ordering.
Pump or valve: diagnosing before you buy
Not every pressure fault means a new pump. Low pressure, pulsing or a machine that won't build pressure often points to the unloader valve, worn seals or a blocked inlet. Replacing the valve first can save the cost of a full pump.
If the pump knocks, leaks from the crankcase or has lost output despite a good valve and clean inlet, a replacement pump is usually the answer. Read the pump parts listings to see whether seals or a full unit suits the fault.
- Pulsing or surging: check the unloader valve and inlet filter
- No pressure: check the valve, seals and water supply
- Knocking or crankcase leaks: likely a pump replacement
Buying guide
Choosing Pumps & Unloader Valves
- How do I know a replacement pressure washer pump will fit my machine?
- Match the drive type, shaft size and mounting pattern to your old pump, and compare the rated pressure and flow to the machine's data plate. Check the inlet and outlet port sizes on the listing too. If any detail doesn't match, don't order it.
- What does the unloader valve on a pressure washer actually do?
- It redirects pump flow away from the gun outlet when you release the trigger, so the pump doesn't build dangerous pressure against a closed outlet. It also holds working pressure while you spray. A faulty valve shows up as pressure loss, surging or a pump running hot.
- Do I need a new petrol pressure washer pump or just a new unloader valve?
- Check the valve first if the machine pulsates, surges or won't hold pressure. A new pump is usually needed when the pump knocks, leaks from the crankcase or has lost output with a good valve and clean inlet. Fitting the wrong one wastes time and money.
- How can I make pressure pumps for pressure washers last longer?
- Keep the inlet filter clean and supply clean water without running the pump dry. Don't leave the machine running with the trigger released for long periods, as that heats the pump. Replace worn seals early and store the machine so the pump doesn't freeze.
- Can I set an unloader valve to a higher pressure than the machine's rating?
- No. Never adjust a valve above the pressure the pump and machine are rated for, since this overloads the pump, hoses and fittings and creates a safety risk. Check the data plate and the product listing for the stated limits before making any adjustment.