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Troubleshooting; Adjusting Unloader Valves - Kärcher HD 2.8/20 Pb Operator's Manual

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PrOBleM
lOW OPerATING
PreSSUre
flUCTUATING
PreSSUre
Unloader valves are preset and tested at the factory
before shipping. Occasional adjustment of the unloader
may be necessary to maintain correct pressure.
Start with the valve set at its lowest spring tension. Raise
pressure by turning adjusting knob clockwise until pres-
sure is at the desired position. Do not overtighten.
12

TrOUBleSHOOTING

POSSIBle CAUSe
Faulty pressure gauge
Insufficient water supply
Old, worn or incorrect spray nozzle
Belt slippage
Plumbing or hose leak
Faulty or mis-adjusted unloader valve
Worn packing in pump
Fouled or dirty inlet or discharge valves
in pump
Worn inlet or discharge valves
Obstruction in spray nozzle
Leaking pressure control valve
Slow engine RPM
Pump sucking air
Valves sticking
Unloader valve seat faulty
Valves worn
Blockage in valve
Pump sucking air
Worn piston packing

AdjUSTING UNlOAder vAlveS

9.800-083.0 • Rev. 01/08
SOlUTION
Install new gauge.
Use larger supply hose; clean filter at
water inlet.
Match nozzle number to machine and/or
replace with new nozzle.
Tighten or replace; use correct belt.
Check plumbing system for leaks. Re-tape
leaks with teflon tape.
Adjust unloader for proper pressure. Install
repair kit when needed.
Install new packing kit.
Clean inlet and discharge valves.
Replace with valve kit.
Remove obstruction.
Rebuild or replace as needed.
Set engine speed at proper specifications.
Check water supply and possibility of air
seepage.
Check and clean or replace if necessary.
Check and replace if necessary.
Check and replace if necessary.
Check and replace if necessary.
Check water supply and air seepage at
joints in suction line.
Check and replace if necessary.
Open and close spray gun to be sure pressure is correct.
Raise or lower pressure by adjusting the knob.
Do not by-pass more than 1-2 minutes when by-passing
to the suction side of the pump.

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