Karcher 720 Pressure Washer (1.842-910.0): Low Pressure, Checking Pump, Replacing Seals & O-Rings

Hello, I have a question about the old model Karcher k720 m eu (1.842-910.0) The washer does not give pressure - the maximum is 40bar on the tachometer. I am not sure of anything because the washer was bought "supposedly" working from a dishonest trader. The gun looks like an ori from this model, but the final vario lance is definitely from a different model, probably with a k5 - rotary with a white plastic "spout" at the end. Does a different lance matter if there is no pressure?

I replaced the seals on the oil pistons - for high pressure no .: 28 and 25


And I replaced O-rings No. 13, 21, 18



and replaced the O-rings No. 9



I do not know how to get to parts 17 and 12 - I do not know exactly how to take it out so as not to damage these baskets - I can remove the front baskets without any problems, but the back part - I have no idea - maybe someone knows?

Please help

Please check the condition of the valves Pump has a certain capacity at the planned pressure The diameter of the outlet nozzle affects the pressure The vibrating nozzles in cheap washers are plastic, which leads to enlargement (pressure drop) Normal nozzles are metal with a ceramic top. the model should give about 150 bar on the correct nozzles.

omnibus111 wrote:

Please check the condition of the valves

are we talking about those that I can't take out? 17 and 12?

what a lance looks like this one - probably from some d3 or d4



Added after 10 [hours] 24 [minutes]:

Update:

lance - damaged - the nozzle is broken in half that's why he pee without pressure

probably no repair kits?

I connected the lances with the rotary nozzle and the washer breaks - I suspect - it's probably clogged!

similar effect:
https://youtu.be/v-ftQpsWohg?t=25s

And one was not clogged It seems to me that the same as the vario lance - it is not from this model.

What lances with a flat tip should be chosen and what size should it be? ?????
Added after 13 [hours] 8 [minutes]:
I am now more than sure that the vario lance (damaged) and the lance with the rotating nozzle will not work properly because the size of the nozzles is different!

Someone will help me determine what nozzle should be for this model? I'm betting 35? But I don't know if I am wrong !?

Can anyone help?

Hello
Did you manage to remove the baskets with valves from the pump? I also face this problem and for me the front ones cannot be pulled out, except through a stone. Should they come loose?

They are fitted very tightly (pressed in)! and they look delicate. The topic of jumping pressure was simple for me - the lance, and its nozzle to be exact, was wrongly selected - or more precisely, it was too small - chosen from another, weaker model. That's why the washer worked in leaps, gave it to the maximum and reduced the pressure to zero and so on. I recommend the techkar shop and their professional knowledge and experience - they made it very easy to solve my problem.