JLG 40H Service Manual - Manual (Page 121)

SECTION 3 - TROUBLESHOOTING
3120240 – JLG Lift –
3-9
Table 3-4. Chassis Assembly Troubleshooting.
TROUBLE PROBABLE CAUSE REMEDY
CONTROL VALVES.
Valve spool sticking. Dirt in oil causing excessive temperature build-up.
Incorrect valve mounting causing warping of the
unit.
Valve spool scored.
Return spring weak or broken.
Relief valve malfunctioning causing excessive
pressure within valve.
Change oil using recommended viscosity and flush
system.
Loosen valve and check mounting. Repair as nec-
essary.
Remove valve and repair or replace as necessary.
Remove valve and repair or replace as necessary.
Check pressure delivery to and from valve and
repair or replace as necessary.
Valve leaking. Dirt or other foreign material under seal.
Valve spool scored.
Excessive back pressure caused by restricted
return line to reservoir.
Damaged valve seal(s).
Remove and repair valve as necessary.
Repair or replace valve.
Remove line and clean obstruction or replace line as
necessary.
Repair or replace valve as necessary.
FUEL SYSTEM.
Strong fuel odor during machine
operation. Fuel tank overfilled.
Fuel tank damaged.
Fuel line from tank damaged.
Filter or carburetor fuel leak.
Check fuel tank and immediately wipe up any spilled
fuel.
Drain all fuel from tank and remove tank for replace-
ment or repair.
Replace fuel line.
Determine cause of leak and make appropriate
repairs.
FRONT FRAME AXLE AREA.
One or both front wheels will not steer. Steering link or tie rod broken or attaching hardware
missing. Replace steering link, tie rod or hardware as neces-
sary.
One or both front wheels will not rotate or rotate
erratically. Wheel hub or bearings damaged or not lubricated.
Hub attachment nut loose or missing.
Replace hub or bearings as necessary and repack
bearings with approved grease.
Secure or replace hub attachment nut and cotter pin
as necessary.
Oscillating Axle will not hold properly. Air in oscillating axle hydraulic system.
Cam Valve Stuck or leaking.
Lockout cylinder leaking.
See bleeding procedure in section 2.
Repair or replace cam valve.
Repair or replace cylinder.