GMC 1976 ZEO 6083 Maintenance Manual page 340

housing in a clockwise/counterclockwise mo-
tion will cause the clutch to free-wheel, which is
normal condition when operated in this manner .
This should not be considered a test by which
replacement is determined .
c. Position thermometer so that it is located
between the fan blades and radiator . This can be
achieved by inserting the sensor through one of the
existing holes in the fan shroud or fan guard, or by
placing between the radiator and the shroud . On
some models, it may be necessary to drill a
3/16"
hole in the fan shroud to insert thermometer.
CAUTION :
Check for adequate clearance be-
tween fan blades and thermometer sensor
before starting engine.
d. With thermometer in position, cover radia-
tor grille sufficiently to induce a high engine temper-
ature. Start engine and turn on A/C if equipped,
operated at 2,000 rpm.
e. Observe thermometer reading when clutch
engages. It will take approximately
5 to 10 minutes
for the temperature to become high enough to allow
NOTE :
All belt tension checks must be taken
midway on the greatest span of that belt .
A belt that has been previously tensioned is con-
Figure 10-Fan and Drive Belts
BELT TENSION
(FIGURE 10)
0
ENGINE COOLING
6K- 9
engagement of the fan clutch . This will be indicated
by an increase or roar in fan air noise and by a drop
in the thermometer reading of approximately
5-15
degrees F. If the clutch did not engage between
150-
190°F
(65 .6-87 .8°C)
the unit should be replaced .
NOTE:
Be sure fan clutch was disengaged at be-
ginning of test .
If no sharp increase in fan noise or temperature
drop was observed and the fan noise level was con-
stantly high from start of test to 190°F
(87 .8°C),
the
unit should be replaced . Do not continue test past a
thermometer reading of 190°F
(87 .8°C)
to prevent
engine overheating.
f. As soon as the clutch engages, remove the
radiator grille cover and turn off the A/C to assist
in engine cooling. The engine should be run at ap-
proximately
1500
rpm.
g. After several minutes the fan clutch should
disengage, as indicated by a reduction in fan speed
and roar.
If the fan clutch fails to function as described, it
should be replaced .
sidered to be a used belt and should be tightened to
70
to
80
pounds . A belt that has never been tensioned
is considered to be a new belt and should be tight-
ened to 110 to 140 pounds .
Vehicles equipped with automotive air condition-
ing MUST have power steering belt checked and
adjusted if necessary first . Then check and adjust as
required the generator and air conditioning compres-
25-30 FT. LBS.
ENGINE
Figure 1 1-Power Steering Pump Mounting