JLG 2658E3 ANSI Service Manual - Manual (Page 54)

SECTION 3 - TROUBLESHOOTING
3-2 – JLG Lift – 3120762
Table 3-1. Hydraulic System Troubleshooting
TROUBLE PROBABLE CAUSE REMEDY
Hydraulic pump noisy Air bubbles in oil (Reservoir too low)
Oil filter dirty
Replenish oil as necessary
Clean and/or replace filter as necessary
Pump cavitating (Vacuum in pump due to
oil starvation) Oil in reservoir low
Restricated reservoir air vent
Oil viscosity too high
Replenish oil as necessary
Clean vent
Drain system and replace with recommended
oil.Rrefer to Hydraulic Oil Table
System overheating Oil viscosity too high
Main relief set too high
Hydraulic system too low
Drain system and replace with recommended
oil.Rrefer to Hydraulic Oil Table
Adjust relief valve to proper pressure
Replenish oil as necessary
Pump not delivering oil Defective pump on motor Repair or replace motor
System pressure too low Main relief valve set too low
Hydraulic pump not functioning properly
Leak in component, line or fitting
Scored valve spool; scored cylinder
Reset as required
Repair or replace pump
Repair or replace component, line or fitting
Replace valve; replace cylinder
System(s) operate erratically Sticking or binding valve cartridge, piston rod,
etc.
Hydraulic oil not at operating temperature
Clean, repair or replace components as neces-
sary
Allow oil sufficient time to warm up