GMC 4000 Series Service Manual page 35

Sec. 1
Page 28
GENERAL MAINTENANCE
Figure 14— End Play W ave W asher Installation
ground strap is properly positioned before securing
cover.
Seal cap (fig. 12) should be cleaned and re­
packed with water-proof grease before reassembly.
2. Install crank arm on output shaft so that
alignment marks line up with those on cover when
wiper motor is in "PARK'.' position (fig. 7). Re­
place and tighten retaining nut after placing crank
arm in vise.
3. Check operation by connecting assembled
motor to battery as shown in figure 11.
WINDSHIELD WASHER PUMP
GENERAL INFORMATION
The "E" type washer pump used on the "E" type
rectangular non-depressed park wiper motors re­
sem bles previous models somewhat in physical
appearance but it has been changed considerably
internally. Refer to figure 15 for view of pump
mounted on wiper motor assembly. Past model
pumps used a bellows system for the pumping
mechanism whereas the new design incorporates
a piston enclosed in a plastic cylinder housing.
The piston type pump provides higher pressures
and increased volume (fig. 18).
The basic principle of operation is very sim ­
ilar to past model pumps of this type. The pumping
mechanism is powered by a four-lobe cam which
is p ressed on wiper motor output shaft. This cam
G M C S E R V I C E M A N U A L
rotates whenever the wiper motor is running. P ro­
gramming is accomplished electrically and mech­
anically through use of a pump solenoid circuit
and ratchet wheel arrangement.
OPERATION
Conventional Cab Models (Single Wiper Motor)
washer to activate and also causes wipers to ac­
tivate in "LOW" speed. If operator wishes high
speed wiper action he must manually switch to
"HIGH" speed. At the end of washer cycle, washer
will automatically shut off; wiper must be shut off
manually, regardless of high or low speed.
Tilt Cab Models (Two Wiper Motors)
switch causes washer to activate, and also causes
left-hand wiper to activate in "LOW" speed. If
operator wishes "HIGH" speed and/or right-hand
wiper action also, he must manually control both.
At the end of washer cycle, washer will automatic­
ally shut off; wiper(s) must be shut off manually
regardless of speed (both left- and right-hand).
PUMP REMOVAL (Figs. 15 and 16)
making certain they are properly marked to a s­
sure correct installation.
terminals.
Figure 15— W asher Pum p Attaching Screws
Pushing in on the wiper switch knob causes the
Pushing in switch knob of left-hand wiper
1. Disconnect water hoses to washer pump
2. Disconnect electric wiring from washer