JKM

I have a Karcher brand , model HD 850 S , 240v single phase 19 amp electric motor (60 Hz) That is in need of some TLC. It probably only has 60 - 70 hours of use on it , but it is easily 7 years old , and hasn't been used often the last couple of years.

The last time I tried to use it , it would not pump at all , the motor ran , but the only pressure on the wand end was from the garden hose pushing water through. Prior use to that , it would pump sometimes , sometimes when you pulled the trigger , there was no pressure.

I took the pump off , and dis-assembled what I could of it (no large torx bits at home) and aside from finding a piece of dirt in one of the check valves ( I think it was a check valve) i could not find anything obviously wrong.

Does anyone have any ideas here? parts source?

Anything would be helpful , thanks.

Edit- I forgot to mention that once i put the pump back together , and on the motor , it is back to working intermittently , but it still doesn't pack the same amount of punch that it did before, the pressure is way low. What controls the pump, I assume it works similar to a load sensing hydraulic circuit.

TonyB

I'll ask my buddy tonight...he found a local shop in Phx Az that sold him ~$20 in parts to recover a pressure washer that I think had the same symptoms.

Tony

03 ant a hemi

The unloader valve which controls the pressure may be stuck/worn.
You may need to replace the seals in the head of the pump/ unlaoder valve.
maybe the pistons need to be replaced.

If you go to the Karcher website they have diagrams for all their machines.

Take a look at the seals, If it has sat for any lenght of time they may be worn out. Also you may just have another peice of dirt in the valves head.

Make sure that you use sililcone o ring lubricant when you re assemble the pump.

RamNu2

Check the numbers of pump and what not and then dross refernce to Grainger or Nothern Tool and see what you come up with. Grainger has millions of parts/motors/tools and stuff to sell to you to fix it cheap.

JKM

I tried looking around the Karcher Website (canadian version) and i couldn't find anything useful , everything just took me to a dealer listing, and the closest one is a 3 hour round trip , and only open during the week , when I work.

I Am going to check the numbers , but , i don't have a northern tool anywhere even remotely close to me , and Gringer is useless In Canada , it's called Acklands-Grainger up here , and they will only sell to you if your a business that regularly deals in stuff they sell , which is not me.

TonyB

I spoke to my buddy this morning...he'll get me a website tonight.

Sorry for the delay!

Tony

SolarExpress

In a pinch, an allen wrench will work to remove the torx bolts. Also, I'm with 03antahemi and guess the unloader valve is toast.

spunbearing

It's common for those valves to stick. Find the valve and soak it in a light oil. It'll probably break loose. If it's the kind that I'm familiar with it has a steel ball and spring. If you live in an area with alot of minerals in the water the ball will stick to the seat.

JKM

I think I have solved part of the problem , I found most of a broken O ring jammed in one of the three check valves ( this is an axial pump btw , not the normal style) I picked out all the pieces that were not supposed to be in there , so I think that should solve my pressure problem, I also found that the unloader had free travel , but not within the entire range of travel , there was several places where it would stick. I ran out of time to work on it last night, but i am going to wetsand the inside of the piston bore ( for the unloader) with some emery cloth to clean it up and put some new O rings in.

Jim Lane

I have a diesel fired Karcher Steam cleaner that had low pressure and it had cracks in both of the ceramic pistons. Make sure the soap injector is closed if you have one, if it gets if any air in the system you will not get high pressure.
If you do any work on the electrical wiring they are not wired to normal color codes, it is European (German)
Jim

C Schomer

I've built a few custom washers for specific gpm and psi and I know Graingers and Northern tool are worthless when it comes to real tech talk about washers. I've had good luck with AAA Pressure Washer in Phx. Sounds like you found the problem. I was also going to say it was the unloader had everything been OK in the pump. When the unloader opens, the discharge water goes right back into the inlet side. If you want to check if the unloader leaks, pinch off the outlet hose from the unloader and listen for a change in the sound of the pump or watch the amps with a clamp-on. Craig

JKM

Easier said than done , since it is just a passage drilled in the pump body on this model

JKM

Just an Update for everyone, I put the pump back together today , cleaned up the bore for the unloader with some emery cloth , and re-assembled it all. This thing works like it did when it was new, once in a while there is about a half to one second delay before the pressure comes on when you pull the trigger , but i can live with that. Thanks for all the help.

03 ant a hemi

the worst part about pressure washers is waiting for parts if you need them. \