Fixing the unloader valve on your Karcher K-2400 pressure Washer

My name is Jerry Wiersma and I am from West Michigan Power Cleaning Systems in Muskegon Michigan. We are a sales/service center for Karcher (their #1 dealer in the U.S.) and so I can tell you that the biggest problem with the K-2400 is the "unloaders" will stick from time to time causing a complete pressure loss. This was due to the factory not putting enough grease on them in the assembly process. The following is an easy 5-minute fix. You will need a #30 Torx, a straight slot screwdriver and a tube of white lithium grease.

1. With a screwdriver, pry off the silver button (#1) from the black plastic cover (#2).
2. Remove the black plastic cover (#2) from the pump.
3. With a #30 Torx or a Phillips driver, remove the two screws that hold the thermo valve housing (#3) to the pump.
The clearance is limited and you may need a right-angled driver or a bit driven with a wrench at aright angle to the screw.
4. Remove the thermo valve housing (#3), the thermo valve (#5), and the thermo valve spring (#6) from the pump.
5. Connect your garden hose to the input of the pump.
6. Connect the hose, gun and wand to the high-pressure outlet of the pump.
7. Turn on the water to the garden hose. The pressure should force the unloader (#8) out of the pump.
8. If this does not work, start the pump and stand back.
9. Turn off the water (and pump) and find where the unloader (#8) landed.
10. Lightly lube the o-rings at the top and bottom of the unloader with either white lithium or silicon grease.
11. Reassemble the unloader in the reverse order given above.

I found your Web site on the Karcher fix and I wanted to share another fix given to me back before I bought my unit. actually, it is preventive maintenance rather than a fix. I saw all the negative reviews online but also knew of Karcher's reputation in the pump business, so I felt since everyone was having the same problem, there must have been an explanation. I called a shop that specialized in pressure washer repairs and overhauls and asked about this unit and was told that it is an excellent machine but its only problem (hard water deposits) could be avoided by running some antifreeze/water mixture through the pump after it was shut down.
I made a funnel adaptor out of a 1/2" pvc conduit sweep, a small funnel and a hose-end adaptor. When I shut down the machine, I attach the funnel to the inlet fitting, pour in about a half-cup of 50/50, and then pull the pump though a couple of ropes until the green stuff come out the other end. I've had nothing but terrific service from this machine.
Skip Thomsen
Hilo, Hawaii