Hello,

I hope you can help me. I've 'inherited' a 620m pressure washer (it was suggested in part payment of a debt) and have been looking at it to make sure I get it right in using it. Can you confirm one or two things about it's operation? (because no handbook came with it)

First is the 'detergent' tank on top. What is best for that? Is it literally ok to use (1) car shampoo, (2) washing powder, (3) washing-up liquid, (4) bleaches..?

At the 'working end is a rotating control know with + and - on it. I assume this is to control the quantity/volume of detergent sent to the outlet for mixing with water.

I understand it has a pressure-electrical switch which turns on the motor only from the lance-handle and when the water supply-hose is connected and supply turned on. Is this correct?

Many thanks.

Ken Tickle, January 2009

With the Karcher 620M 90% of the problems are the bypass valve is stuck, usually after a prolonged time of being not used, this is located under the micro swith housing, undo the 2 torx screws holding this, then undo the 4 torx screws and take off top of hose housing, this enable you to pull out the bypass valve, you will probably find it is stuck and can be quite hard to pull out, when you've got it out clean out the bore ideally with fine steel wool wound around an 8mm drill bit, lubricate the 2 'O' rings on valve and it will back into the bore with very litle resistance..........JOB DONE......IT WORKS.

Davy62, December 2013

connect machine turn on, pump starts water slow coming out press swisch no pressere any ideas checked valve all o`K

dave taylor, March 2012

I have a Karcher 620 which workls ok except the detergent no longer comes out. Any Ideas

Tom Bonnar, September 2011

I have a karcher 620m but when it is all plug up and turned on the motor still does not kick in any ideas. What it could be and how to repair it

Baasshment, July 2010

hi im thinking of getting one for my caravan how much do they cost foe the 620m thanks jon.

Jon finlay, March 2010

I have one of these and have the manual - I could photocopy and post at cost if you like - I'm in Brisbane Australia

Graham, December 2009

only use karcher deturgent or it will play havock with the auto shut of and wont build up pressure.

T N Belfield, August 2009

BOB has some good tips and here are some more Pressure Washer Tips from www.sparesgiant.com :

Extension leads :
We have found that electrical extension leads can cause motor problems due to voltage drops. Make sure your extension lead has at least 1.5mm conductors although 2.5mm are better. Unwind the full reel as cable left on a drum loses power.

Chemical and Shampoo :
Make sure the cleaning fluid is the viscosity of water (runny not a gel). We see lots of machines gunged up with fairy liquid.

Water Couplings :
Most people use the plastic garden snap on fittings made by Hozelock or Gardena. We have seen issues with the auto-couplings (the ones that switch off the water automatically when you disconnect the couplings) Auto couplings can restrict the water flow and make your pressure washer loose pressure.

TSS or By-Pass :
Some machines switch off when you release the trigger this is called a Total Stop System other just circulate the water this is called By-Pass. If your machine is the by-pass type do not leave the machine By-Passing for more than a few minutes. If your machine is TSS dont forget to switch the machine off if you have finished using it.

Protect from frost

Accessory Care :
Most home use Pressure Washers have a plastic pressure hose which is easy to kink and wear out. Take care to uncoil the hose and not to pull at it. Take care not to snag the hose on corners or rough terain. Dont be too trigger happy this can cause premature by-pass wear.

Technical Help at www.sparesgiant.com, January 2009

www.karcher.co.uk contact us very top of page in small white letters. They may email if small enough instructions. If not
1. Connect a MCB to the socket you will be using. It's a safety measure.
2. Connect the unit to elect if using extension lead place in plastic bag in case of pressure splash back when using washer. Again safety as water and elec don't mix well. fine in the machine of course.

3. USE shampoo for vehicles cleaning and liquid soap for blasting the muck off the pvc on house/conservatory. Liquid soap contains salt and isn't very kind to vehicle paint work I'm told.

4. Connect garden hose ensure it's secure on machine.

5. With machine power switch in OFF position turn on the water and the operate the lance trigger to ensure water flows ie: tank in machine is full as pump must not run dry.

6. Switch power switch to ON it [mine does]will start and immediately stop and will only start when trigger pulled. So start spraying.
Now for the + and - these are on mine on the end collar of the lance and turned to - allows flow of shampoo or soap through then returned to + bring back pressure spraying. It's obviously a method of also reducing pressure for thing that may 'take off' if hit by full force of spray. This is how mine works and I think yours is not much different.

I'm sure the machines are similar so if you don't understand or have no joy with the Karcher site then email me robertwhiting76@hotmail.com and I'll send you the picture operator diagram of my Macallister B&Q machine as again the basics are similar.
The balls in your court.

bob, January 2009