JCB 230v pressure washer

[yardie]

Water still coming through but only seems to be at mains water pressure. Pressure Washer turns on and sounds like its working i.e motor is running at what sounds like the correct speed without any unusual noises (not humming suggesting motor seized or starter cap failure), mains pressure is good, cleaned mesh filter on the main water inlet connector, no visible water leaks anywhere.
Theres also a sliding pressure control 'switch' which makes no difference when changed from min to max.
Not been used for probably around a year and stored in a dry shed.
Not familiar with these so wanted advice before attempting repair.
Thanks.

 

[DaveHerns]

It's not got an airlock , has it?

 

[Burnerman]

The problem is likely to be a cracked pump head......vague I know, but as these machines try to compress water, the top of the pumping chamber cracks and the water recycles at low pressure instead of blasting through the lance. External leaks aren't normal here.
Any chance of some pictures? If the internals are by Karcher, there's a chance of a repair, but otherwise I doubt its a goner.
John

 

[yardie]

Thanks, shall strip down and take photos tomorrow.

I did strip it down and clean it up today, not really dirty though, reassembled and it did have some pressure but sure its not as much as it should be.

Not a very good description but this is how I understand it from my initial inspection:
A metal disc sits on a ring of bearings that is sat at an angle covered in oil, this turns via the pump which in turn pushes 3 pistons down that have return springs, this must cause suction that draws up a plastic plunger thats spring loaded (housed in a plastic 'cap') which draws water from the inlet and out to the smaller bores. There are no signs of water leakage in the oil or in the piston chambers.
There is more to it but can't remember from memory the arrangement to explain, not that this is a very good explanation.

 

[Burnerman]

That's actually a very good description......the spinning disc works as a plate cam that operates the pistons in sequence. In the chamber where the pistons enter are valves......depending on their orientation governs whether that piston pumps or sucks. The pistons that pump have the valve facing away from it, and its in the chamber containing the valves that could well be fractured. As the fracture is internal, water doesn't escape to the outside but rather continues to recirculate internally. Its possible for a valve to stick too, but this is less likely......see if you can extract them for a check!
Usually these chambers fracture because the machine has been used without the lance trigger depressed - even a short time can cause the compressing water to boil, and then when the trigger is pressed, incoming cold water causes the fracture.
If the rubber seals between pistons and chambers are leaking, then water emulsifies with the oil. Your machine seems to have escaped that.
You would think that the name JCB would indicate a solid, well built and nigh on indestructible product but sadly that's not the case.....they just sold their name and logo to some oriental outlet!
John

 

[yardie]

20160123_124131

• yardie
• 23 Jan 2016

20160123_122737

• yardie
• 23 Jan 2016

operates a switch which cuts out power to the motor when activated by screwing in the min/max pressure control valve

20160123_122705

• yardie
• 23 Jan 2016

pistons

20160123_122641

• yardie
• 23 Jan 2016

pison springs and retaining clips

20160123_122637

• yardie
• 23 Jan 2016

outlet valves

20160123_122621

• yardie
• 23 Jan 2016

inlet valves

20160123_113551

• yardie
• 23 Jan 2016

pressure control valve

 

[Burnerman]

Everything does look canny there, I have to say but do scrutinise all of the castings very carefully for cracks.
After that, see if you can work out how the pressure adjustment screw is functioning - maybe the plunger it makes contact with is bent?
You are certain the motor is actually spinning, of course?
Its pretty unusual for there to be no increase in pressure at all - even a faulted unit would normally provide some increase.
(There's also a good chance that when you put the thing back together again, things have improved.)
John

 

[yardie]

Not yet been able to remove the cut out valve but it does operate and the spring returns it so assuming thats ok.
There is some pressure just not as much as it should be.
Cannot see any cracks or anything else amiss.
Certainly sounds like motor is turning and like I say there is some pressure, just doesnt blast like it used too.

Could be a number of other things too I suppose:
worn plastic valves not sealing properly
Worn plastic valve seats
Gasket between inlet and outlet bores
Worn o rings

This machine has had very little use, 3 times since we have owned it from new, about 5 years ago.

 

[yardie]

20160123_151951

• yardie
• 23 Jan 2016
• 1

motor cut out actuator and housing outlet valve

 

[yardie]

Dmm across cap reads 410v which looks good but for £3 I shall swap out just to check it is running motor at full power.

 

[Burnerman]

That pressure relief valve in the last pic.....its not bent, is it? If its a clamped in type, try leaving the clamps loose and giving it a go.
John

 

[Dave54]

I don't know anything specifically about pressure washer pumps. I haven't had the "pleasure" of pulling one apart yet. A couple of questions though. Is the swashplate (the angled cam plate) actually turning? It's not loose on the shaft? Also it's not adjustable for angle and has moved?

 

[yardie]

Cleaned up and reassembled, much better pressure but...
Its now cutting in and out when switched on but gun trigger not pressed, at the same time its causing the house lights to flickers. This did not happen before, I am guessing its to do with the cut out switch/actuator.
When its switched on with the gun trigger pressed it works fine without causing the lights to flicker.

Shall have to investigate further and adjust the min/max pressure control valve.

 

[yardie]

That pressure relief valve in the last pic.....its not bent, is it? If its a clamped in type, try leaving the clamps loose and giving it a go.
John

I don't think its bent.
The actuator valve assembly slides into the housing most of the way then taps in 'home' so don't think its a clamped type.

 

[yardie]

I don't know anything specifically about pressure washer pumps. I haven't had the "pleasure" of pulling one apart yet. A couple of questions though. Is the swashplate (the angled cam plate) actually turning? It's not loose on the shaft? Also it's not adjustable for angle and has moved?

The swashplate appears to be bolted to the motors armature and is fixed tight. Not adjustable or moved.
Yes it is definately turning.