JLG 260MRT Service Manual - Manual (Page 85)

SECTION 3 - GENERAL ELECTRICAL INFORMATION & SCHEMATICS
3121801 – JLG Lift – 3-19
Table 3-3. Hydraulic System Troubleshooting
TROUBLE PROBABLE CAUSE REMEDY
Hydraulic System - General
Hydraulic Pump Noisy
Air bubbles in oil. (Reservoir too low.) Replenish oil as necessary.
Oil filter dirty. Clean and/or replace filter as necessary.
Pump cavitating. (Vacuum in pump due to oil starvation)
Oil in reservoir low. Replenish oil as necessary.
Restricted reservoir air vent. Clean vent.
Oil viscosity too high. Drain system and replace with recom-
mended oil. Refer to Hydraulic Oil.
System overheating
Oil viscosity too high. Drain system and replace with recom-
mended oil. Refer to Hydraulic Oil.
Main relief valve set too high. Adjust relief valve to proper pressure.
Hydraulic system oil low. Replenish oil as necessary.
Pump not delivering oil
Defective pump. Repair or replace pump.
System pressure too low
Main relief valve set too low. Reset valve as required
Hydraulic pump not functioning properly. Repair or replace pump.
Leak in component, line or fitting.
Repair or replace component, line or fit-
ting.
Scored valve spool; scored cylinder. Replace valve; replace cylinder.
System(s) operate erratically
Sticking or binding valve cartridge, piston
rod, etc. Clean, repair or replace components as
necessary
Hydraulic oil not at operating tempera-
ture. Allow oil sufficient time to warm up.