Faulty pressure washer

[PCAnimal]

Hi, my dad gave me a clarke pressure washer 140.
I used it yesterday to blast the patio and it worked like a dream. Today i went to use it and nothing happened. No fuse blown no noise just silence.

It was suggested that the capacitor could be faulty. Sadly my dad passed away recently so i can't ask him how to fix it.

When i turn the switch on it is passing power through. So i don't think its a faulty switch


Can anyone recommend a test or common fault please?

 

[SimonH2]

If the cap is faulty then you could expect quite a hum from the motor when you switch it on - and if you don't switch off again quickly enough, a blown fuse.
Looking at it, it's almost certainly a permanent capacitor motor - it looks like the live is connected to the red lead for the main winding, and the capacitor is between live and the white lead to provide the phase shifted current for the second winding. And neutral connected to the blue lead.
First check would be to make sure it's unplugged, and check the resistance of the two windings - red-blue and white-blue. Between red and white should be the sum of the other two. My guess is that the white-blue winding will have a higher resistance than the red-blue one.
Assuming that checks out, the next check is a live check. This is NOT TO BE UNDERTAKEN LIGHTLY and great care should be taken.

With the machine plugged in and switched on, check the voltages between blue and red, and between blue and white, wires. blue-red should be at mains voltage, blue-white will probably be less, but definitely non-zero.
If blue-white is zero (or at least very low), and white-red is close to mains voltage, then that says the capacitor is dead.

 

[Jackrae]

I take it you actually had the water supply connected and turned on - the system may have a low water feed pressure cut-out

 

[SimonH2]

There's no sign of such a cutout in the photos provided - just mains in, switch, cap, and connections to motor.

 

[davelx]

If the windings checkout, a new cap is less than a tenner so worth a try if you don't feel confident doing the live checks.

 

[PCAnimal]

Hi thanks for the replies. I think the first safe and easy test is to replace the cap. I've ordered a new one. If that fails then onto the multimeter to try the other route. I will let know

 

[PCAnimal]

I've fitted the new Cap and absolutely nothing changed Now I am not sure what to do. After the cap it leads to a little black plastic box at the bottom. There is power to this but I don't know what it is. Back to the drawing board

 

[Jackrae]

Have you look for/at the water low-pressure switch ?

 

[SimonH2]

Not seen a pressure switch on a small pressure washer - they are mostly intended to be able to draw water from a bucket etc.
PCAnimal - can you sketch what's connected to what. In the photo in your first post, all I can see is the mains in, switch, capacitor, and motor. And can you post a photo showing this little back plastic box - assuming it's not the one we can see the insides of above ?

 

[jj4091]

There is a user manual with maintenance guide & parts list as a PDF here clarke pressure washer 140 if that is any help.

 

[DaveHerns]

This switch might be the unloader, designed to take the pressure of the motor when it starts. Photo needed

 

[davelx]

These units usually use a spinning vane pump, like a car water pump. They don't need a valve to unload them to start the motor - indeed they usually have a pressure switch to turn the motor off when the trigger on the lance is released, which stop the flow. The resulting pressure increase turns the motor off. When the trigger is pressed, the pressure in the hose is released, the pressure switch closes and starts the motor again, at which point there is no pressure in the system so nothing to unload. That's now my Nilfisk works.

Worth checking the pressure switch but note that if it the type of unit described above it will be Normally Closed, i.e. closed when NOT under pressure.

 

[SimonH2]

There is a user manual with maintenance guide & parts list as a PDF here clarke pressure washer 140 if that is any help.

Yes, helpful - but sadly doesn't have any details of the internals. But the operation section does imply that there is a pressure switch to stop the motor when the lance trigger valve is closed.

This switch might be the unloader, designed to take the pressure of the motor when it starts. Photo needed

The manual talks about the pressure being equalised across the pump - implying that the inlet (to the pump) is pressurised when stopped (much the same thing really !)

These units usually use a spinning vane pump, like a car water pump.

Unlikely, a centrifugal pump would struggle to produce the sort of pressures needed for a practical pressure washer - they are typically used for high flow and relatively low pressure applications. The manual for this washer talks about seals on the pistons - showing that it is a piston pump as I'd expect.

 

[PCAnimal]

I'm home on thursday to take a photo. I will try that process in pg10 of the user manual.. thanks for the help i really hope i get this going

 

[PCAnimal]

Hi, i had a go at measuring voltage and resistance but didn't really have a clue. From the switch it was reading 120 to 140. I could probably do with a bit of a step by step to do it please?
I turned the motor and some water came out. Still no joy on starting.
After it wouldn't start last time ive not connected any water. I don't need to have it connected do i? When it used to work with no water connected the pump still fired up humming