Diagnosing a Faulty Pressure Washer

Pressure washers are now common in most households, and although they are usually very reliable there are a number of problems that can occur with them which can generally be repaired by a competent D.I.Y. enthusiast.

For information on how to tackle and resolve faults and problems on a wide range of appliances see our other articles »



There are 3 main reasons for leaking occurring with your pressure washer...

Worn or Damaged Seals:

Disconnect the electrics and hoses and remove the casing, then reconnect the hoses and turn on the water supply.

If water appears to be running from the motor side of the cylinder head then it is likely the seals are worn or damaged. Dismantle the pump assembly and replace the seals or the whole cylinder head.

Split Pipes:

This is most often caused by water in the appliance freezing during cold weather. Trace and replace the damaged component. If the appliance is stored in a cold environment, purge water from the pump by running the washer for 2 seconds without the water supply hose attached.

Damaged Hoses or Connectors:

Replace the hose or connectors as required.

Motor Does Not Remain "Off":

The pump runs as normal and delivers high-pressure water when the handgun trigger is squeezed, but when the trigger is released the motor pulses instead of automatically shutting off.

This problem suggests the pump is running correctly, as it delivers high pressure water and it shuts the motor off when the handgun is released. However, the fact that the motor comes back on after a second or so would indicate that the high pressure in the pump is leaking away, and the pump is repeatedly attempting to repressurise.

This loss of pressure can be caused by a fault with the seals on the cylinder head (which will leak water), the one-way valves inside the cylinder head, the cage (a type of valve), the inlet elbow (which comes with a type of pressure release valve) or the control head (which is also likely to leak if faulty).

However it is unlikely to be clear which part is faulty, necessitating a systematic replacement of each of these parts until the issue is resolved.

Most pressure washers have a high power (1.7kw) induction motor, incorporating a capacitor that couples the electricity to one of the windings. If this capacitor fails, the motor may run at lower pressure when the handgun trigger is pressed, but may be unable to restart under pressure after the trigger is released. Replace the capacitor if this is the case.

 pressurewasher Spares and accessories

Keep the cables away from water as much as possible and connect with an RCD Safety Device automatically switching off if a fault is detected.

Get the Part: View our range of RCD safety device

* All information provided is a guide only. BuySpares accepts no liability for any problems occurred while attempting any advice shown. If in any doubt contact a qualified repair service.

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