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FAN DRIVE CLUTCH
FIG. 12 Typical Fan Drive Clutch
Installation
ance (drive) area. This action deter-
mines the fan speed in relation to the
drive pulley and the radiator core air
flow
temperature.
OPERATION
START-UP
At start-up, or after a prolonged
engine shut-down period, near maxi-
mum fan noise can be heard as the
fan clutch fluid is forced into the
close clearance area by centrifugal
force, resulting in maximum applica-
tion of the clutch
.
As the normal op-
erating temperature is reached, the
amount of fluid allowed to remain in
the close clearance area is regulated
by the temperature-sensitive control
valve.
This determines fan speed in
relation to the fan drive pulley and
the radiator core air flow tempera-
ture.
RUNNING-LOW AMBIENT
TEMPERATURE
After the initial start-up
·
cycle has
been completed, and as long as the
air flowing through the radiator core
does not exceed
150-
180 degrees F
temperature, the fan clutch will re-
main in or near the maximum slip
position. During this cycle, the con-
trol valve allows a minimum amount
of fluid to remain in the close clear-
ance (drive)
area.
RUNNING-HIGH AMBIENT
TEMPERATURE
As ambient temperatures increase,
or air flow temperatures through the
core become increasingly higher, ad-
ditional cooling is required. The bi-
metal coil or strip senses this change
PART 11-2- WATER PUMP
11-9
BI·METAL STRIP
CONTROL
PIST~
82631·8
FIG. 13
-
Fan Drive Clutch With
Flat Bi-Metal Spring
and moves the control valve to the
minimum slip position, retaining a
maximum amount of oil in the close
clearance area
.
MODULATING CYCLE
As vehicle operation varies with
heavy to light traffic, terrain, etc., the
fan clutch operates within the high
and low rpm positions, modulating as
required as ambient air flow through
the radiator core changes
.
HIGH SPEED SUSTAINED
OPERATION
During high speed operation, fan
clutch action will limit speed of the
fan to a given maximum rpm
.
This
will occur under hot or cold condi-
tions.
REMOVAL
1. Remove the radiator shroud
attaching bolts and lay the shroud
back toward the engine.
2.
Loosen the fan belt. Remove the
capscrews
retaining
the
fan
drive
clutch to water pump hub (Fig. 1).
Remove the fan drive clutch and fan
as an
assembly.
TORQUE VALUES (ALL CARS)
BI-METAL SPRING
8 1932
-
C
FIG. 14 -Fan Drive Clutch With
Coil Bi-Metal Spring
3. Remove the retaining capscrews
and separate the fan from the drive
clutch
.
INSTALLATION
I. Position the fan on the drive
clutch
.
Install the capscrews.
2. Position the fan drive clutch and
fan assembly to the water pump hub
(Fig. I). Install and torque the retain-
ing capscrews evenly and alternatel
y
to specifications. Then, check the fan
drive clutch flange-to-water pump hub
for proper
mating.
Adjust the fan belt
tension to
specifications.
3. Re-install the radiator shroud.
NOTE: All specifiutions are aiven in ft·lbs unless otherwise noted.
Fan to Fan Clutch (With A/C)· All Engines
10-15
Enaine RPM Required Fan Test Speed
@
2000 Water Pump RPM
To Run Water Pump
Maximum Slip
Minimum Slip
2000 RPM<D
(Cold) <D
(Hot) <D
1695
1500
1750
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