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Plunger Pumps
Operating Instructions and Parts Manual RK Series Pumps
Symptom Possible Cause(s) Corrective Action
Oil leak between
crankcase and pump-
ing section
Worn rod oil seals Replace crankcase piston rod
seals
Frequent or prema-
ture failure of the
packing
1 Cracked, damaged or worn
plunger
1 Replace plungers
2 Overpressure to inlet
manifold
2 Reduce inlet pressure
3 Material in the fluid being
pumped
3 Install proper filtration on pump
inlet plumbing
4 Excessive pressure and/or
temperature of fluid being
pumped
4 Check pressures and fluid inlet
temperature; be sure they are
within specified range
5 Running pump dry 5 Do not run pump without water
Pump runs but pro-
duces no flow
Pump is not primed Flood suction then restart pump
Pump fails to prime Air is trapped inside pump Disconnect discharge hose from
pump. Flood suction hose,
restart pump and run pump until
all air has been evacuated
Pump looses prime,
chattering noise,
pressure fluctuates
1 Air leak in suction hose or
inlet
1 Remove suction line and inspect
it for a loose liner or debris
lodged in hose. Avoid all unnec-
essary bends. Do not kink hose
2 Clogged suction strainer 2 Clean strainer
Low pressure at
nozzle
1 Unloader valve is by-pass-
ing
1 Make sure unloader is adjusted
property and by-pass seat is not
leaking
2 Incorrect or worn nozzle 2 Make sure nozzle is matched
to the flow and pressure of the
pump. If the nozzle is worn,
replace
3 Worn packing or valves 3 Replace packing or valves
Pressure gauge fluc-
tuates
1 Valves worn or blocked by
foreign bodies
1 Clean or replace valves
2 Packing worn 2 Replace packing
Low pressure 1 Worn nozzle 1 Replace with nozzle of proper
size
2 Belt slippage 2 Tighten or replace with correct
belt
Troubleshooting