SECTION 3 - TROUBLESHOOTING
3120743
– JLG Lift –
3-13
Table 3-5.Hydraulic System - Troubleshooting
TROUBLESHOOTING CHART
TROUBLE
PROBABLE CAUSE
REMEDY
HYDRAULIC SYSTEMS - GENERAL.
Hydraulic pump noisy.
Air entering system through broken line or fitting.
(Suction Side.)
Repair or replace line or fitting.
Air bubbles in oil. (Reservoir oil too low.)
Replenish oil as required.
Oil filter dirty.
Replace hydraulic filter.
Wrong type of hydraulic oil.
Replace hydraulic oil.
Pump cavitating. (Vacuum in pump due to oil starvation.)
Restricted suction line.
Clean, repair, or replace line.
Restricted reservoir air vent.
Clean or replace vent.
Oil viscosity too high.
Drain system and replace with recommended oil.
(Refer to Hydraulic Oils.)
Air leak in suction side of tank.
Repair leak.
System overheating.
Oil viscosity too high.
Drain system and replace with recommended oil.
(Refer to Hydraulic Oils.)
Bypass valve not operating properly.
Repair or replace valve.
Main relief valve set too low.
Reset valve as required.
Hydraulic system oil low.
Replenish oil as necessary.
Port relief set too high.
Reset valve as required.
Restricted or blocked return line.
Repair or replace line.
Pump not delivering oil.
Restricted suction line.
Clean, repair, or replace line.
Air entering system through broken line or fitting.
Repair or replace line or fitting.
Defective motor/pump.
Repair or replace motor.
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