Lack of pressure in a karcher 455. motor powers on changes sound as trigger is depressed but water remains at mains pressure. oil replaced and had no water in old oil. any ideas.

SOURCE: Karcher K 3.68M Electric Pressure Washer. Wand trigger Locks Up.

Sounds like the pressure valve is broken thats why you cant depress the trigger , the valve is on the pump , i would suggest taking it to a repair shop as they are fiddly things to fix

SOURCE: my karcher pressure washer has lost its water power

I have the same problem. With mine I have to remove the tip that I am using then pull the trigger and then replace the tip and pull and pressure should return. I believe that one of my valves is sticking causing me to reprime the pump frequently. I am trying to clean or replace my valves to fix the problem.

I hope this helps.

SOURCE: karcher 520m spill valve jammed

Clean the spill valve!

David Koss

• 102 Answers
• Posted on Mar 15, 2009

SOURCE: the motor is pulsing on and off without the trigger being pressed

It is probably sucking air on one of the connections or around one of the fittings at the regulator. You can also turn the pressure up allittle on the regulator, that might stop it also. Make sure the clamps on the hoses going to the regulator is tite. Also it could be that the regulator is just bypassing water and if it has air in it it will pulsate.

SOURCE: POWER CRAFT BY Karcher bought Aldi on 31Mar 05.2100Watts 130 bar.

You did winterize the machine? Leaving water in a powerwasher will freeze and damage the pump. It's a common happening, because people don't think of it or are not told by the maker.