Appendix F—Trouble Shooting Guide for the PT-Series Pump
Problem Cause Solution
Low capacity Pump speed too slow Check engine speed and PTO ratio. Consult pump performance
curve. Use tachometer on pump if speed is questionable.
High differential pressure Restriction in discharge piping or hose too small.
Pump speed too high.
Clogged strainer Clean strainer.
Suction pipe too small Indicated by pump inlet pressure dropping several
or restricted pounds when pump is started. Remove restriction
or modify piping.
Worn vanes Replace.
Worn sideplates Reverse or replace sideplates. Check universal drive
assembly to make sure angularity is within limits, yokes
are parallel and slip-joint is greased. Check bearings.
Vanes sticking Remove vanes and clean out foreign material
(check strainer). Replace vanes if swollen.
Pump runs Valve closed Check valves. Make sure tank valve is open!
but no ow
Refer to manufacturer’s instructions.
Broken shaft Disassemble and inspect pump. Repair if necessary.
Defective meter Service meter.
Pump will not turn— Foreign matter in pump Clean out the pump—check strainer in suction line.
locked up
Vanes broken Clean out pump carefully and replace vanes.
Has pump been operated dry? Then, check for damage
to cam and rotor shaft assembly.
Bearing seized Replace pump bearings. Grease monthly. Use ball
bearing grease manufactured for intended service.
Moisture frozen in pump Let thaw and break loose carefully.
Will not build Poor suction conditions Clean inlet strainer. Increase pipe size.
pressure
Internal bypass valve set Check valve or set valve for higher pressure (see instructions).
too low or stuck open
Worn vanes Disassemble, inspect and repair as necessary. Has pump been
and/or sideplates run dry? If so check for damage to vanes & rotor-shaft assembly.
Pump is noisy Cavitation from poor Clean inlet strainer. Increase pipe size.
suction conditions
Vanes sticking Remove vanes and clean out foreign material
(check strainer). Replace vanes if swollen.
Bearings worn Replace if necessary—grease monthly.
Check for restriction in discharge line. Delivery hose
Very high differential
too small and too long? Slow down pump!
pressure
Check vapor release oat assembly on meter air eliminator
and meter differential valve.
PTO shaft vibration Inspect and repair driveline component.
Pump leaks
Seal or O-rings failed Inspect seal assembly and replace if necessary. Keep
around shaft
new seal very clean when replacing seal. Recommend
a light oil lm on O-rings. Has pump been run dry? If so check
for damage to vanes & rotor-shaft assembly.
In diagnosing pump and system troubles, record the following data during product transfers:
1. Pressure at pump suction.
2. Pressure at pump discharge.
3. Pipe size and length of suction and discharge lines.
4. Pump speed if practical.
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