Pressure washer leakage problem

May 16, 2008 15 Replies
M

When I switched on my (Karcher KB 9030) pressure washer for the first time this year there was no pressure and water was gushing out of the casing. I opened it up and found that the plastic elbow (connecting the high pressure hose to the compressor) was cracked. So I Googled the part number, ordered a new part, fitted it. Easy.



I guess the frost must have got to it.



Then after a few minutes, use another leak started, identical to the first, but on the inlet side this time. No problem it was only a fine spray and it didn't seem to have any effect on the performance.



Then after about half-an-hour's use bugger me it developed yet another leak. This time it's a fairly major leak where the second inlet elbow joins onto the compressor.



Photo:

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better close-up of leak 3:
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result of the leak is that when the outlet is closed the motor starts and stops about once a second, and water leaks out of the casing. When the outlet is open everything seems to work fine.



I'm not so keen to tackle this problem because it looks like I'll have to remove the metal cover and I suspect it won't be quite so easy to reassemble.



Anyone got any experience of this?


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G

So whats the alternative or what have you got to lose?

When a pressure washer has not been used for sometime? the idea is to hold the lance in one hand ready to operate the trigger and turn on the water with less force then switch on the PW and operate the lance trigger in short burst till the jet builds up pressure,then open the tap more for more force.

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A

Sounds like the plastic has all rotted. Have you ever used it with any chemicals?

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B

Seems to be grasping at unlikely explanations! 3 leaks all more or less at once round the joints after winter - surely the OP's original suggestion of frost damage is the most likely??

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M

No and no.

Has anyone here taken the metal housing off one of these (or similar), and if so, is it easy to put back together gain?

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M

The alternatives are (1) try to repair it, and risk not being able to reassemble it - unless anyone here can help with information, which is why I'm asking, and (2) carry on using it and put up with the noise and leakage when the output is switched off.

I've not head that before. I do make sure that water is flowing before I turn the electricity on.

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T

Highly likely.

The leak is on the high pressure side of the pump head and is causing the auto stop start to get confused. Long term use like this will cause damage.

I'm assuming this machine has a swash plate pump, unlikely to be anything else (just looked & it does). There are two parts to the head, the pressure head & the crank, called housing 1 & housing 2 on this diagram

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the pressure (26 on the diagram) by undoing the bolts (27) should reveal a gasket which has probably gone. Should be simple to do, just make sure you don't lose any o rings. Shouldn't be any pingfuckits. Don't attempt to remove the crank/housing 2 because you probably need special tools to get it back.

HTH

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M

Actually I'm pretty sure it's on the low pressure side but the effect seems to be the same.

That's what I was afraid of.

Yes, thanks. I'll finish the current batch of jobs, strip it down, and see what I find. I suspect a new part 8 is required, or (if I'm really lucky) just its O-ring.

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A

WHat is a swash plate pump and how does it work? Enquiring minds need to know.

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R

A lovely little animation of how they work:

(A former life with anorak friends and a certain interest in diesel hyrdaulic locomotives equipped me with the basic idea. But Google was need for anything more.)

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A

That's clever. I've never seen it before.

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T

Early high pressure pumps like the American CAT or the German Speck work by having pistons driven by a crankshaft, rahther like a car engine. They were extreemly durable, but best run at around 1400rpm, and expensive to make.

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swash plate or axial pump can be run faster, so can use a cheaper 2800 rpm motor and are much cheaper to manufacture. They also have the advantage that performance can be changed just by altering the swash plate angle, so you make one pump and have 6 swash plates.

Three piston swash plate pumps are the norm, two piston really need a pulsation damper, four piston are a bit of overkill.

Good picture here

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This shows the valves integral with the pistons, they are usually in the head casting.

HTH

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T

Seems to be a difference in terminology here. What the pressure washer industry would call a swash plate pump is described as a wobble plate pump on this site.

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R

Very similar at heart.

Let's throw the helicopter version in as well:

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