Discussion for the Karcher K 3.97M-Plus (1.423-115.0) Pressure Washer
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Question: Karcher K3.97M Does Not Strt On ...
Electric Karcher K3.97M about 10 yrs old. Used only once or twice per season. Garage stored (never below zero). Flushed clean and ran dry after each use. Problem is when I use the wand with the adjustable pressure (+ and -). (The one you use when using the solvent suction line.) Pump starts with trigger, but only on low pressure, regardless of whether the wand is set to + or -. To get it to kick into high pressure, I must hold the trigger in, then rotate the wand pressure from + to - and then back to +. It then runs at high pressure until I let go of trigger. Next time I pull trigger, I need to do the same thing all over again. This "works", but it is a pain in the rear to do every time I need to let go of the trigger. If I switch to the "rotary" wand (which runs at high p ressure only), everything works works fine. The problem is that that wand cannot be switched to low pressure to use the suction line. My water hose is a dedicated 3/4" ID industrial-grade hose which I use for the Karcher only because I wanted to be sure I always had adequate pressure and flow at the inlet. It has worked perfectly with the same hose for 10 years, until this season. Unloader problems? Is there an easy solution? I have no problems with disassembly & reassembly (I'm a retired professional engineer), but I've never torn apart a pressure washer yet. To save time, I had hoped to get some ideas and suggestions before I tear into it.
Reply: Karcher K3.97M Does Not Strt On ...
It's disappointing to see that these forums are apparently not monitored, since I see no follow-up to this question.
On my K3.97M, the pump stalls when I close the trigger. I can start it again by spinning the fan with it switched off, then switching on again.
On a gasoline-powered pressure washer, I would look at the unloader valve, but I don't see an equivalent part in the parts diagram for this one.
Mark's tear-down video of a similar Karcher Electric model seems clear to follow, but I need to know what parts to order that need replacement.
Question: No Pressure
My wand has a leak and it appears to be in the hand held nozzle. Could it be o-rings that are leaking?
Reply: No Pressure
Mine just sprung a leak - took it apart and found a hair-line crack in the white plastic part (holds the tiny spring toward nozzle end - other end where water line connects).