Karcher's service handbook for its pressure washer water pump specifies specific tools that must be used to troubleshoot and service components of the water delivery system. Among these tools are oil and water pressure seal mounting tools, special pliers for valve removal, grease for water seals and tubes and 10W50 oil for piston lubrication.
Seal Mounting Tools
Seal mounting tools are used to mount three oil seals in the piston housing of Karcher pressure washers. Seal mounting tools play an important role in the assembly of pressure washers because oil seals keep oil inside the washers' piston reservoirs. Seal mounting tools are also used to replace three-weep-hole high-pressure seals in Karcher pressure washer water pumps. High-pressure seals must be replaced if water is leaking from the weep holes.
Valve pliers are used to remove inlet filters from Karcher pressure washers. Filter removal is necessary for the cleaning and replacement of filters. Clogged water inlet filters are a cause of low water pressure. Valve pliers are needed to remove thermal relief housing in the process of accessing pressure washers' bypass valves. Bypass valves must stay lubricated at all times, so accessibility is of the utmost importance in the functioning of Karcher pressure washers. Valve pliers effectively remove high-pressure check valves. High-pressure check valves that show pitting, debris or wear in any form must be replaced.
Silicone grease is used to lubricate high-pressure water seals in Karcher pressure washer water pumps. Silicone grease is also applied to the nipples of water exiting detergent tubes in Karcher pressure washers. The grease helps the detergent check valve's O-ring adhere to the detergent tube nipple.
Pump Oil 15W40
Karcher's non-detergent pump oil 15W40 is used to saturate and soak the pistons and swash plate in Karcher pressure washers. The oil maintains the revolving of the swash plate. With every swash plate revolution, pistons receive one suction stroke and one pressure stroke. When a piston is driven back in the oil bath housing, it closes the high-pressure valve allowing water to enter the water inlet suction chamber. The opposite action with the piston pushed forward in the oil reservoir causes the low pressure check valve to close and water is sent to the high-pressure outlet.
Lithium grease is a Karcher tool used to lubricate the large O-rings on Karcher pressure washer bypass valves. Bypass valves in the pressure washers' thermal relief housing must stay lubricated with lithium grease to prevent them from sticking and malfunctioning. Sticking bypass valves are a cause of low water pressure.