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Plunger Pumps
Operating Instructions and Parts Manual RK Series Pumps
First Choice When Quality Matters
NORTH
AMERICA
Symptom Possible Cause(s) Corrective Action
Low pressure (cont.) 3 Air leak in inlet plumbing 3 Disassemble, reseal and reas-
semble
4 Relief valve stuck, partially
plugged or improperly
adjusted valve seat worn
4 Clean and adjust relief valve;
check for worn or dirty valve
seats
5 Worn packing. Abrasive
in pumped in cavitation.
Inadequate water
5 Install proper filter suction at
inlet manifold must be limited to
lifting less than 20 feet of water
or 8.5 psi vacuum
6 Worn inlet, discharge valve
blocked or dirty
6 Replace inlet and discharge valve
Pump runs extremely
rough, pressure very
low
1 Inlet restrictions and/or air
leaks.
1 Clean out foreign material
2 Stuck inlet or discharge
valve
2 Replace worn valves
Water leakage from
under manifold
Worn packing or cracked
plunger
Install new packing or plunger
Slight leak, oil leak-
ing in the area of
crankshaft
1 Worn crankshaft seal or
improperly installed oil seal
o-ring
1 Remove oil seal retainer and
replace damaged 0-ring and/or
seals
2 Bad bearing 2 Replace bearing
Excessive play in the
end of the crankshaft
pulley
Worn main bearing from
excessive tension on drive
belt
Replace crankcase bearing and/or
tension drive belt
Water in crankcase 1 Humid air condensing into
water inside the crankcase
1 Change oil intervals
2 Worn packing and/or
cracked plunger
2 Replace packing. Replace
plunger
Loud knocking noise
in pump
1 Cavitation or sucking air 1 Check water supply is turned on
2 Pulley loose on crankshaft 2 Check key and tighten set screw
3 Broken or worn bearing 3 Replace bearing
Troubleshooting (cont.)