17
Maintenance
Troubleshooting
PROBLEM
POSSIBLE CAUSE
SOLUTION
LOW OPERATING
PRESSURE
Faulty pressure gauge
Install new gauge.
Insufficient water supply
Use larger garden hose; clean filter washer
at water inlet.
Old, worn or incorrect spray nozzle
Match nozzle number to machine and/or
replace with new nozzle.
Plumbing or hose leak
Check plumbing system for leaks.
Retape leaks with teflon tape.
Faulty or misadjusted unloader valve
(where applicable)
Adjust unloader for proper pressure. Install
repair kit when needed.
Worn packing in pump
Install new packing kit.
Fouled or dirty inlet or discharge valves
in pump
Clean inlet and discharge valves.
Worn inlet or discharge valves
Replace with valve kit.
Leaking pressure control valve (where
applicable)
Rebuild or replace as needed.
FLUCTUATING
PRESSURE
Valves worn
Check and replace if necessary.
Blockage in valve
Check and clean out if necessary.
Pump sucking air
Check water supply and suction line for air
seepage at joints.
Worn piston packing
Check and replace if necessary.
PRESSURE LOW
AFTER PERIOD OF
NORMAL USE
Nozzle worn
Check and replace if necessary.
Inlet or discharge valves blocked or
worn
Check and clean or replace if necessary.
Unloader valve seat worn
Check and replace if necessary.
PUMP NOISY
Air in suction line
Check water supply connections on
suction line.
Broken or weak inlet or discharge valve
springs
Check and replace if necessary.
Foreign matter in valves
Check and clean if necessary.
Worn bearings
Check and replace if necessary.
PRESENCE OF WATER
IN PUMP OIL
Water sprayed at machine
Change oil. Direct spray away from
machine.
High humidity in air
Check and change oil twice as often.
Piston packing worn. Oil seal worn
Check and replace if necessary.
Karcher HDS Series Operator’s Manual 9.800-967.0 - C
