JLG 660SJ Service Manual - Manual (Page 236)

SECTION 5 - HYDRAULICS
5-26 – JLG Lift – 3121202
NOTE: The outside diameter of the seal may be lightly
coated with sealant (such as Loctite High Perfor-
mance Sealant #59231) prior to installation. This will
aid in preventing leaks caused by damage to the
housing seal bore.
5. Slide the new seal over the shaft and press it into the
housing bore. Be careful not to damage seal. A seal
installer tool can be made to aid in installing the
seal.
6. Reinstall the seal retaining ring.
BYPASS VALVE (PUMP)
1. Unscrew the bypass valve from the housing. Inspect
the valve and mating seat for damage or foreign
material. It is recommended that the O-ring and
back - up ring be replaced.
NOTE: Bypass valves are available with integral bypass ori-
fices for specific applications. Refer to the appropri-
ate Service Parts Manual for more information.
2. Reinstall the bypass valve into the housing. Torque
to 7 to 10 ft. lbs. (9.5 - 13.6 Nm).
CHARGE CHECK AND HIGH PRESSURE RELIEF
VALVES
1. Remove the charge check and high pressure relief
valve hex plug.
2. Remove the spring and check poppet or valve car-
tridge from the housing. Inspect the valve and mat-
ing seat in the housing for damage or foreign
material. It will be necessary to replace the housing
if the seat is damaged.
3. Several designs of charge check and high pressure
relief valves have been used. Do not attempt to mix
different vintage parts.