GMC 4000 Series Service Manual page 28

INSTALLATION (Fig. 1)
NOTE: If desired, sealing cement can be ap­
plied between lip of seal and glass and seal lip at
cab opening flange.
1. Reposition rubber seal on cab opening
flange. Raise new glass to outside of seal; then
with hook end of installer tool (J-2189) in glass
groove of seal as shown in figure 1, move tool
around glass to force outer lip of seal over edge
of glass.
2. Thread end of rubber insert through handle
and loop of installer tool (fig. 1). Push tool loop
and end of insert into groove of seal. Feed in rub­
ber insert, while proceeding around window. Use
a hitching movement of tool to avoid elongating
insert. If new insert is being used, cut off insert
allowing sufficient overlap for a tight joint; then
butt into groove.
3. Install insert in center vertical seal (2-
piece windshield) in same manner previously des­
cribed in Step 2.
REAR W IN D O W GLASS REPLACEMENT
(ALL CABS)
Rear window glass is retained by means of
GENERAL DESCRIPTION
Conventional cab and steel tilt models have
two-speed electric E-type windshield wipers with
washers as standard equipment. The wiper assem ­
bly used on cowl, "P," and school bus models is
determined by the body manufacturer.
A single wiper motor, mounted on engine side
of cowl, powers both wiper blades on conventional
cab models. Two separate motors are used with
tilt cab models where each wiper motor is bracket-
mounted to rear side of cowl under dash.
Tilt cab models employ separate wiper motor
control switches; the left switch incorporates a
push-type control for operation of windshield
washers.
WIPER ARM ADJUSTMENT
To adjust sweep of blades to provide maximum
visibility, turn on wipers, then note sweep of arms.
CAUTION: DO NOT A T T E M P T TO
M A N U A L LY MOVE
DAMAGE TO LINKAGE OR MOTOR MAY
OCCUR.
If necessary, remove arms as follows:
G M C S E R V I C E M A N U A L
WINDSHIELD WIPERS
W IP E R ARMS AS
GENERAL MAINTENANCE
rubber seal and seal insert (fig. 1). No sealing
compound or cement is used.
If body prevents access to rear window, glass
can be installed from inside cab by reversing seal
so that insert is located inside cab.
1. Pry end of seal insert out of seal with a
pointed tool; then remove rubber insert completely.
Push glass from inside cab. Pull seal from opening.
2. If necessary, straighten any irregularities
of seal flange in cab opening which may have caus­
ed breakage of glass.
3. Install new rubber seal over panel flange,
pushing it completely into corners. Avoid stretch­
ing seal during installation. Cut seal to allow suf­
ficient overlap for a tight joint, then butt ends.
4. Position glass to seal and insert hook end
of installer tool (fig. 1) into seal groove. Move tool
around glass to force outer lip of seal over glass.
5. Thread end of rubber insert through handle
and loop of installer (fig. 1). Push tool loop and end
of insert into groove at bottom center of window.
Feed in the rubber insert while proceeding around
window. Use a hitching movement to avoid elong­
ation of insert.
6. Cut off end of insert, allowing sufficient
overlap for a tight joint; then butt into groove.
CONVENTIONAL CAB MODELS
1. Pull outer end of arm away from glass
which will trip lock spring at base of arm and re­
lease spring from undercut of pivot shaft.
2. While holding arm in this position, pull out­
ward on cap section at base of arm to remove the
arm.
Figure 3 — Wiper Arm Installed (Tilt Cab)
Sec. 1
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