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PAGE 64 — MAYCO LS400/LS500 PUMP — OPERATION AND PARTS MANUAL — REV. #6 (09/19/11)
TABLE 9. PUMP TROUBLESHOOTING (CONTINUED)
Problem Possible Problem To Troubleshoot
Main Hydraulic Pump Noisy
Insufficient oil
Check oil level and for closed suction
strainer
Air in system
Check for aeration reservoir
Vacuum leak in suction line
Excessive pump wear Repair or replace
Excessive engine speed Check for correct engine RPM
Engine bogs down
Low engine speed Check engine RPM
Main relief cartridge set to low Adjust relief cartridge
Engine overloaded when pumping
Decrease volume control on main
pump
Material hose pack
Machine does not deliver volume and
pressure
Low engine speed Check engine RPM
Volume control set to low Adjust control to full open setting
Main hydraulic pressure too low
Check for proper pressure or for
contaminated relief cartridge
Hydraulic fluid gets hot
Cooling fan
Check fan electrical connection or for
burnt fan motor.
Fan rotating in wrong direction
Contaminated cooler fins Clean cooler fins
Return filter element closed Replace filter
Main relief cartridge contaminated or
set too low
Replace or set to proper pressure
Hydraulic oil level too low Fill to proper level
Accumulator gauge reads below 1750
PSI
Accumulator bottle low on notrogen Check precharge pressure 1100 PSI
Contaminated safety relief cartridge Replace cartridge
Defective unloader cartridge electrical
coil
Replace
Unloader cartridge coil not energizing Check for 12 Volt signal voltage
Defective gear pump Replace pump
Concrete slurry in lubrication box
Worn or defective urethane cups or
worn material cylinder
Replace
Material cylinder piston cups squeel Low on lubrication Check oil level
Cylinders not completely extended
(short stroke)
Excessive amount of hydraulic on
cylinder rod side
Inspect cylinder. Check values for
contamination or faulty spring
Hydraulic cylinder piston head seal
leaking
Replace seals
LS400/LS500 PUMP — TROUBLESHOOTING (PUMP)