JLG 25RTS Service & Maintenance page 72

SECTION 3 - TROUBLESHOOTING
TROUBLE
Hydraulic pump noisy
Pump cavitating (Vacuum in pump due to oil star-
vation
System overheating
Pump not delivering oil
System pressure too low
System(s) operate erratically
3-8
Table 3-4. Hydraulic System Troubleshooting
PROBABLE CAUSE
Air entering system through broken line or fitting
Air bubbles in oil
Faulty pump coupler
Defective pump bearing
Oil filter(s) dirty
Restricted suction line
OIl in reserve low
Restricted reservoir air vent
Oil viscosity to high
Leak in suction line or manifold
Oil viscosity too high
Restricted or blocked hydraulic line
Machine overloaded
Main relief valve set too high
Hydraulic system oil low
Restricted suction line
Air entering system through broken line or fitting
(suction side)
Oil level too low
Plugged strainer in tank
Pump coupling defective
Broken pump drive shaft
Main relief valve set too low
Main relief valve stuck in open position
Hydraulic pump not functioning properly
Leak in component, line or fitting
Scored valve spool; Scored cylinder
Sticking or binding valve spools, piston rod, etc
Hydraulic oil not a t optimum operating tempera-
ture
Pump drive slipping
– JLG Sizzor –
REMEDY
Repair or replace line or fitting
Replenish oil as required
Replace coupler
Repair or replace pump
Clean and/or replace filter(s) as necessary
Clean, repair, or replace line
Replenish oil to proper level
Clean vent
Drain system and replace with recommended oil
(Refer to hydraulic oils)
Repair or replace line or manifold as necessary
Drain system and replace with recommended oil
(Refer to hydraulic oils)
Repair or replace line
Check weight in platform
Reset valve as required
Replenish oil as necessary
Clean repair or replace line
Replace or repair line or fitting
Replenish oil to proper level
Clean strainer
Replace pump coupling
Repair or replace pump
Reset valve as required
Clean, repair or replace valve (Check system oil for
contamination)
Repair or replace pump
Repair or replace component, line or fitting
Replace valve; Replace cylinder
Clean, repair or replace components as required
Allow oil sufficient time to warm up
Repair or replace drive
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