Hi

 

Had my Karcher k403 pressure washer many years now.

 

Using last weekend and when in standby the machine was pulsing and leaking from somehwre inside the case. Pressure was also down when in use.

 

Decided I would have a look inside (checked supply pressure from tap/hose first).

 

Water was leaking from around the cylinder head. Removed cylinder head and found that one of the piston o rings was split. New o rings are £2.50 each (need 3) so decided to buy a complete new cylinder head that includes the o rings and low/high pressure values.

 

Suggestions on various forums confirmed my diagnosis as being correct i.e. water is leaking out so the machine keeps switching on and off to try to maintain pressure.

 

New cylinder head fitted last night.

 

No leaks but machine still pulses and pressure still down.

 

Not keen on taking to a dealer as the machine is probably 10 years old and just not worth spending £50+ for some to fix it.

 

Don't know what else to try.

 

Any suggestions?

 

Mark

Karcher do a fixed price repair and service - my mum just sent hers off.

 

Hers was originally a almost £300 pressure washer and failed the same as yours - I think hers was a fixed price of £70 and they would fix whatever needed to be done. The way I look at it at half decent replacement for hers would be £150 so its worth the £70 to get it refurbed.

 

Take a look here: http://www.karcher.co.uk/uk/Service/Home__Garden_Machine_Repairs_and_Servicing.htm

To the OP, sounds like frost damage to me. 

The induction motored models are worst for this..

I got mine done on the fixed price thing with the exact same issue. 

Whole new motor unit required in mine so £75 was cheap really.. 

3 months warranty on the work. 

But their pricing varies dependent on model. 

Should have spent the money on a Nilfisk really but would have

to buy new snow foam gun and stuff.

If you get it fixed then find somewhere indoors to keep it. 

Don't think it is frost damage.

 

The machine has for the last 10 years been kept against an internal wall in an integral garage. It's been working fine all this year so far but just started playing up on Saturday.

 

I just don't feel it is worth spending say £70 on a 10 year old machine. I would rather put another £70 to it and get a half decent Nilfisk - wouldn't buy another Karcher at the consumer end of the market.

 

If I can fix it myself for a few quid then I'm happy with that.

Does the pump pulse without water feed or sound steady?

Recheck cylinder head/test it without head fitted.

Check filter on inlet fitting for obstruction.

Could be a faulty capacitor but most probably water starvation, so check:

1. water source is good.

2. feed hose stop valve (if fitted) working OK and let's full flow through-poke with screwdriver.

3. inlet hose screw fitting filter is clear.

Hi MicMac

 

Thanks for the suggestions:

 

Does the pump pulse without water feed or sound steady?

 

If I release the trigger on the lance the pump runs as normal. Haven't tried it without water as I thought that didn't do the pump much good.

Recheck cylinder head/test it without head fitted.

 

I have no leaks from anywhere after fitting new cylinder head. Do you mean run the machine without a water supply with the head removed?

Check filter on inlet fitting for obstruction.

 

Checked that last weekend - all clean. Even tried the machine briefly without filter fitted.

Could be a faulty capacitor but most probably water starvation, so check:

1. water source is good.

 

Plenty of pressure on outside tap. Even tried an alternative outside tap.

2. feed hose stop valve (if fitted) working OK and let's full flow through-poke with screwdriver.

 

Don't have one fitted.

3. inlet hose screw fitting filter is clear.

 

see above.

 

 

 

Thanks aagin for the suggestions.

 

Mark

Your washer has an automatic stop/start?

Disconnect water in/out.

Motor should run smoothly and evenly.

Connect inlet making sure outlet is facing away from anything damageable including things that breathe.

Does water shoot out steady or pulse?

When you say pulse, is auto stop/start in effect or motor just... pulses?

If auto stop/start is fine, motor runs smoothly and steady then the only fault lies within the pump mechanism.

Regardless of leaks, I'd be stripping it to check for damaged o rings etc as before, could be you bought duff head?

OK - understand what you are saying.

 

The machine has auto stop/start.

 

By pulse I mean that when the machine is in standby i.e. water connected and powered up, the motor keeps switching on and off repeatedly about once every 1 second. When I press the trigger on the lance the motor runs as it should but the pressure is down.

I'm assuming you've let it have a good run to purge any air and no leaks would suggest high pressure is leaking back to low causing the on/off behaviour.

Check the pump, although you fitted new head it isn't fitted correctly or is faulty.

Short of refitting old head with new head o rings and testing I'd be returning new head.

Perhaps it has unseen defect.

Have you tried it without lance connected? Does flow seem OK?

Does lance have a variable pressure nozzle? Incorrectly adjusted?

Good idea about trying the new o rings in the old head - I'll give that a try.

 

Without lance connect flows seems to be down and the machine still pulses.

 

Lance is variable but machine pules regardless of setting.