Karcher hds 1200 Questions

[marinegrunt 1]

Sorry if I posted this in the wrong section being that I'm currently just a homeowner but thought it was the best category. 

My father-in-law recently acquired a Karcher hds 1200 be from a friend's place of work. It supposedly was stored away years ago but ran fine then. Supposedly doesn't have very many hours on it. Father in law couldn't get water to come out of the hose so he gave it to me. There was just muck in the handle. The engine starts but one side has weak spark. New coil will be here tomorrow so I'll know more on it then. It does idle up but was bogging a tad.

I guess what I'd like to know is what would you recommend be done to this 1993 machine? Should the pump be rebuilt or only if it shows signs that it needs it? Is there any maintenance that should be done to the heating system or anything else? I did change engine and pump oil already. What's the maximum amount of money I should throw at it? It doesn't seem like there could be too much wrong because it did idle up pick up pressure. I shut it down right away due to the weak spark and engine bog.

One thing I did notice is that when started water was coming out of the holes on the safety valve (part number 6412267) right away before warm up.

If I get this pressure washer in good working order is it one that could get someone started in a part time cleaning business? With my main job I usually have enough time off during warm weather where I've been considering doing something on my own. If this machine could do just that I figure it may be worth a try. I would probably stick to residential and maybe farm machinery. I'm a busy body and work non-stop around the house even when I'm not working I might as well try and make some extra cash.

Anyways, I figured I had better start a thread because I know I'll have more questions about it. I'm okay with the engine work it's just the rest of the unit I might need some help with.

Thanks in advance for any help or advice.

[Beth n Rod 1,278]

If the Thermal Safety valve is leaking, it needs to be replaced.
It's purpose is to protect the pump in the case of water recirculating for prolonged periods of time
without the trigger on the gun being pulled. As water recirculates, it gains heat from the pump and 
over a few minutes can get to temperatures that will eventually harm the pump.

The valve allows a discharge of water once it reaches a  pre-set temperature allowing cool water to
enter and releasing the heated water. Once the water temp drops enough, it usually shuts off and allows
the unit to continue to function.

Now, if it is the pressure relief valve, it has to be replaced every time it blows. It is a safety function of the unit
to prevent the machine from exceeding it's operating pressure. It has no re-set ability. The foil seal will burst
and cannot be repaired.

Rod.

[marinegrunt 1]

Thanks for the explanation on how the safety valve works. I took it apart just to see and it looked like there was some muck preventing it from closing. It has a little brass piston or valve with a gasket disc on the end. It looks like the only thing that could fail would be the o-rings or that gasket disc. Everything else is brass.

Parts are hard to source for this thing. Seems like there is only one place online from the U.S. and a couple other places are overseas. 

Thanks again!