GMC 4000 Series Service Manual page 50

DOOR W IN D O W GLASS HORIZONTAL
SEAL REPLACEMENT
1. Remove the vent window and door window
as directed previously under applicable headings.
2. Using a thin flat-bladed instrument, pry
REMOVAL
NOTE: N ecessary equipment for efficient and
safe replacement of cab consists of a chain hoist
(3/4-ton minimum capacity), a sling having padded
hangers, and two or more support blocks to rest
cab on once the cab is removed from chassis.
1. Disconnect the battery.
2. Remove the hood panels.
3. Drain cooling system if equipped with heater
and disconnect heater hoses at cab cowl.
4. If equipped with air brakes, exhaust the
pressure from air system .
5. Disconnect all necessary wiring harnesses
and cables from cab or chassis.
6. If air conditioned, refer to "AIR CONDI­
TIONING" section and open system and cap lines
observing precautions found in above references.
7. Detach and/or disconnect all lines between
cab and chassis.
NOTE: Do not attempt to salvage clutch or
brake hydraulic fluid.
8. Disconnect accelerator linkage at cab cowl.
9. Disconnect mechanical parking brake.
10. Remove closure panel from cab floor at
transmission shift lever.
11. Disconnect speedometer cable at trans­
m ission or at the dash unit.
12. Mark for alignment purposes later, the
steering shaft joint flange-to-steering gear shaft,
then remove the flange clamp bolt. When cab is
raised later, this connection will separate.
13. Remove the cab mounting bolts.
14. With a hoist sling device having padded
hangers, open doors and engage hangers to cab
door openings. DO NOT ATTACH HANGERS TO
DOORS.
NOTE: If sling device of type described above
is not available, a solid hardwood 4 x 4, 1% . feet
HEATERS
Two types of heaters may be used in these
conventional cabs, the standard duty air-flow type
(fig. 28), and the heavy duty air-flow type (fig. 29).
G M C S E R V I C E M A N U A L
seals from door panel in manner shown in figure
27. Pry a small amount at each fastener to prevent
seal channel distortion.
door panel.
CAB REPLACEMENT
long, positioned through the cab with' hoist chain
attached securely to each end, can be used. Place
padding at points where beam contacts cab.
INSTALLATION
on chassis frame brackets. If desired, masking
tape can be applied to retain loose parts tempor­
arily in position.
same time engage the steering shaft to gear shaft
using marks made prior to removal for alignment.
Tighten shaft clamp bolt (when used) to 35 to 40
foot-pounds torque or clamp bolt nut (when used)
to 40 to 50 foot-pounds torque.
cooling system .
used.
new fluid.
this section, for service of the air conditioning
system, if used.
Refer to SHEET METAL (SEC. 11) of this manual.
and control linkage.
start engine, then final check all connections and
linkage.
CAB HEATING A N D VENTILATION
All the heater components are located within cab,
under the dash.
formation for each type heater is explained under
applicable headings. Service diagnosis information,
CONVENTIONAL CAB
3. To install, press seal assembly evenly into
4. Install door glass.
15. Raise cab and remove from chassis.
1. Place cab mounting components in position
2. Carefully lower the cab to chassis and at
3. Install balance of cab mounting components.
4. Connect speedometer cable.
5. Connect hand brake if mechanical.
6. Connect accelerator linkage.
7. Connect all control and gauge lines.
8. Connect fuel line if previously disconnected.
9. Connect heater hoses (if used), then fill
10. Service the hydraulic brake system , if
11. Service the clutch hydraulic system. Use
12. Connect all electrical wiring.
13. Refer to "AIR CONDITIONING" later in
14. Connect battery cables.
15. Install hood panels and align, if necessary.
16. Recheck all connections of wiring, lines,
17. With wheels blocked as a safety measure,
Description, operation, and maintenance in-
Sec. 1
Page 43