JLG 3969electric ANSI Service Manual - Manual (Page 36)

SECTION 3 - TROUBLESHOOTING
3-6
– JLG Sizzor – 3120768
Table 3-3. Hydraulic System Troubleshooting
TROUBLE PROBABLE CAUSE REMEDY
HYDRAULIC SYSTEM - GENERAL
Hydraulic pump noisy Air bubbles in oil Reservoir oil level low. Replenish oil as neces-
sary
Oil filter dirty Replace oil filter
Pump cavitating. (Vacuum in pump due tooil
starvation) Oil in reservoir low Replenish oil as necessary
Restricted reservoir air vent Clean air vent
Oil viscosity too high Drain hydraulic system and replace with recom-
mended oil
Leak in suction line Repair or replace suction line
System overheating Oil viscosity too high Drain hydraulic system and replace with recom-
mended oil
Hydraulic oil low in reservoir Replenish oilto proper level
Extended driving periods Do not drive machine for extended periods
Pump not delivering oil Defective motor on pump Repair or replace motor
System pressure too low Leak in component, line or fitting Repair or replace component, line or fitting
Hydraulic pump not functioning properly Repair or replace pump
Defective valve cartridge Replace cartridge
Systems operate erratically Sticking or binding valve cartridge, piston rod,
etc. Clean, repair or replace components as
required
Hydraulic oil not at operating temperature Allow oil sufficient time to warm up