wheel DODGE RAM 1500 1998 2.G Workshop Manual

PRESSURE INCREASE
The inlet valve is open and the outlet valve is
closed during the pressure increase cycle. The pres-
sure increase cycle is used to reapply thew brakes.
This cycle controls re-application of fluid apply pres-
sure.
REMOVAL
(1) Install a prop rod on the brake pedal to keep
pressure on the brake system.
(2) Disconnect the battery cables from the battery.
(3) Remove the battery.
(4) Disconnect the two electrical harness connec-
tors (Fig. 5).
(5) Remove the five brake lines from the HCU
(Fig. 5).
(6) Remove HCU/CAB mounting bolts and remove
the HCU/CAB (Fig. 5).
INSTALLATION
NOTE: If the CAB is being replaced with a new CAB
is must be reprogrammed with the use of a DRB III.
(1) Install HCU/CAB on the mounts and Tighten
the bolts to 15N´m (11 ft. lbs.) (Fig. 5).
(2) Install the five brake lines to the HCU and
tighten to 19 N´m (170 in. lbs.) (Fig. 5).
(3) Install the two electrical harness connectors to
the HCU/CAB and push down on the release to
secure the connectors.
(4) Install the battery.
(5) Install the battery cables to the battery.
(6) Remove the prop rod on the brake pedal.
(7) Bleed ABS brake system (Refer to 5 - BRAKES
- STANDARD PROCEDURE).
RWAL VALVE
DESCRIPTION
Rear Wheel Antilock (RWAL) brake system is stan-
dard equipment on 1500 series vehicles. The RWAL
brake system is designed to prevent rear wheel
lock-up on virtually all types of road surfaces. RWAL
braking is desirable because a vehicle which is
stopped without locking the rear wheels will retain
directional stability. This allows the driver to retain
greater control of the vehicle during braking.
The valve is located on the drivers side inner
fender under the hood. The valve modulates hydrau-
lic pressure to the rear brakes.
The RWAL components include:
²RWAL Valve
²Controller Antilock brake (CAB)
²Rear Wheel Speed Sensor (WSS)
OPERATION
When the brakes are applied, hydraulic fluid is
routed from the master cylinder's secondary circuit to
the RWAL valve. From there hydraulic fluid is routed
to the rear brakes. The Controller Antilock Brake
(CAB) contains an Electronic Variable Brake Propor-
tioning (EVBP) control algorithm, which proportions
the applied braking force to the rear wheels during
braking. The EVBP function of the RWAL system
takes the place of a conventional hydraulic propor-
tioning valve. The CAB monitors the rear wheel
speed through the rear wheel speed sensor and cal-
culates an estimated vehicle deceleration. When an
established deceleration threshold is exceeded, an
isolation valve is closed to hold the applied brake
pressure to the rear brakes constant. Upon further
increases in the estimated vehicle deceleration, the
isolation valve is selectively opened to increase rear
brake pressure in proportion to the front brake pres-
sure. If impending rear wheel lock-up is sensed, the
CAB signals the RWAL valve to modulate hydraulic
brake pressure to the rear wheels to prevent lock-up.
NORMAL BRAKING Since the RWAL valve also
performs the EVBP or proportioning function, vehicle
deceleration under normal braking may be sufficient
to trigger the EVBP function of the RWAL system
without full RWAL activity as would normally occur
during an impending rear wheel lock-up. As previ-
ously mentioned, the isolation valve is selectively
closed and opened to increase rear brake pressure in
proportion to the front brake pressure under EVBP
control. Slight brake pedal pulsations may be noticed
as the isolation valve is opened.
Fig. 5 HYDRAULIC CONTROL UNIT
1 - HYDRAULIC CONTROL UNIT
2 - MOUNTING BOLTS
5 - 50 BRAKES - ABSDR
HCU (HYDRAULIC CONTROL UNIT) (Continued)

CLUTCH
TABLE OF CONTENTS
page page
CLUTCH
WARNING.............................1
DIAGNOSIS AND TESTING................1
SPECIFICATIONS........................5
CLUTCH DISC
REMOVAL.............................5
INSTALLATION..........................5
CLUTCH HOUSING
DIAGNOSIS AND TESTING................7
REMOVAL.............................9
INSTALLATION..........................9
CLUTCH RELEASE BEARING
REMOVAL.............................9
INSTALLATION.........................10
FLYWHEEL
DIAGNOSIS AND TESTING................10REMOVAL.............................11
DISASSEMBLY.........................11
ASSEMBLY............................11
INSTALLATION.........................11
PILOT BEARING
REMOVAL.............................11
INSTALLATION.........................12
LINKAGE
REMOVAL.............................12
INSTALLATION.........................12
CLUTCH PEDAL POSITION SWITCH
DESCRIPTION.........................13
OPERATION...........................13
DIAGNOSIS AND TESTING................13
CLUTCH
WARNING
WARNING: Exercise care when servicing clutch
components. Factory installed clutch discs do not
contain asbestos fibers. Dust and dirt on clutch
parts may contain asbestos fibers from aftermarket
components. Breathing excessive concentrations of
these fibers can cause serious bodily harm. Wear a
respirator during service and never clean clutch
components with compressed air or with a dry
brush. Either clean the components with water
dampened rags or use a vacuum cleaner specifi-
cally designed to remove asbestos fibers and dust.
Do not create dust by sanding a clutch discs.
Replace the disc if the friction material is damaged.
Dispose of all dust and dirt containing asbestos
fibers in sealed bags or containers. This will mini-
mize exposure to yourself and to others. Follow all
recommended safety practices prescribed by the
occupational safety and health administration
(OSHA) and the environmental safety agency (EPA),
for the handling and disposal of products contain-
ing asbestos. Failure to follow these instructions
may result in personal injury or death
DIAGNOSIS AND TESTING
Road test and inspect components to determine a
clutch problem. Road test the vehicle at normalspeeds. Shift the transmission through all gear
ranges and observe clutch action. If clutch chatters,
grabs, slips or does not release properly, remove and
inspect clutch components. If problem is noise or
hard shifting, further diagnosis may be needed to the
transmission and driveline component.
CLUTCH CONTAMINATION
Contamination is a frequent cause of clutch mal-
functions. Oil, water or clutch fluid on the clutch disc
and pressure plate surfaces will cause chatter, slip
and grab. Oil contamination indicates a leak at
either the rear main seal or transmission input shaft.
Clutch fluid leaks are usually from damaged slave
cylinder push rod seals. Heat buildup caused by slip-
page between the pressure plate, disc and flywheel
can bake the oil residue onto the components. The
glaze-like residue ranges in color from amber to
black.
Road splash contamination is dirt/water entering
the clutch housing due to loose bolts, housing cracks.
Driving through deep water puddles can force water/
road splash into the housing through such openings.
IMPROPER RELEASE OR CLUTCH ENGAGEMENT
Clutch release or engagement problems can be
caused by worn or damage clutch components.
Release problems can cause hard shifting and
noise. Look for leaks at clutch cylinders, connecting
line and loose slave cylinder bolts. Also worn/loose
release fork, pivot stud, clutch disc, pressure plate or
release bearing.
DRCLUTCH 6 - 1

Engagement problems can cause slip, chatter/shud-
der and noisy operation. The causes may be clutch
disc contamination, wear, distortion or flywheel dam-
age.
CLUTCH MISALIGNMENT
Clutch components must be in proper alignment
with the crankshaft and transmission input shaft.
Misalignment caused by excessive runout or warpage
of any clutch component will cause grab, chatter and
improper clutch release.
CLUTCH COVER AND DISC RUNOUT
Check the clutch disc before installation. Axial
(face) runout of anewdisc should not exceed 0.50
mm (0.020 in.). Measure runout about 6 mm (1/4 in.)
from the outer edge of the disc facing. Obtain
another disc if runout is excessive.
Check condition of the clutch before installation. A
warped cover or diaphragm spring will cause grab
and incomplete release or engagement. Be careful
when handling the cover and disc. Impact can distort
the cover, diaphragm spring, release fingers and the
hub of the clutch disc.
Use an alignment tool when positioning the disc on
the flywheel. The tool prevents accidental misalign-
ment which could result in cover distortion and disc
damage.
A frequent cause of clutch cover distortion (and
consequent misalignment) is improper bolt tighten-
ing.
FLYWHEEL RUNOUT
Check flywheel runout whenever misalignment is
suspected. Flywheel runout should not exceed 0.08
mm (0.003 in.). Measure runout at the outer edge of
the flywheel face with a dial indicator.
Common causes of runout are:
²heat warpage
²improper machining
²incorrect bolt tightening
²improper seating on crankshaft flange shoulder
²foreign material on crankshaft flange
Flywheel machining is not recommended. The fly-
wheel clutch surface is machined to a unique contour
and machining will negate this feature. Minor fly-
wheel scoring can be cleaned up by hand with 180
grit emery or with turning equipment. Remove only
enough material to reduce scoring (approximately
0.001 - 0.003 in.). Heavy stock removal isnot rec-
ommended.Replace the flywheel if scoring is severe
and deeper than 0.076 mm (0.003 in.). Excessive
stock removal can result in flywheel cracking or
warpage after installation; it can also weaken the fly-
wheel and interfere with proper clutch release.
Clean the crankshaft flange before mounting the
flywheel. Dirt and grease on the flange surface may
cock the flywheel causing excessive runout. Use new
bolts when remounting a flywheel and secure the
bolts with Mopar Lock And Seal or equivalent.
Tighten flywheel bolts to specified torque only. Over-
tightening can distort the flywheel hub causing
runout.
DIAGNOSIS CHART
The diagnosis charts Diagnosis Chart describe
common clutch problems, causes and correction.
DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
Disc facing worn out 1. Normal wear. 1. Replace cover and disc.
2. Driver frequently rides (slips) the
clutch. Results in rapid overheating
and wear.2. Replace cover and disc.
3. Insufficient clutch cover
diaphragm spring tension.3. Replace cover and disc.
6 - 2 CLUTCHDR
CLUTCH (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
Clutch disc facing contaminated with
oil, grease, or clutch fluid.1. Leak at rear main engine seal or
transmission input shaft seal.1. Replace appropriate seal.
2. Excessive amount of grease
applied to the input shaft splines.2. Remove grease and apply the
correct amount of grease.
3. Road splash, water entering
housing.3. Replace clutch disc. Clean clutch
cover and reuse if in good condition.
4. Slave cylinder leaking. 4. Replace hydraulic clutch linkage.
Clutch is running partially
disengaged.1. Release bearing sticking or
binding and does not return to the
normal running position.1. Verify failure. Replace the release
bearing and transmission front
bearing retainer as necessary.
Flywheel below minimum thickness
specification.1. Improper flywheel machining.
Flywheel has excessive taper or
excessive material removal.1. Replace flywheel.
Clutch disc, cover and/or diaphragm
spring warped or distorted.1. Rough handling. Impact bent
cover, spring, or disc.1. Replace disc or cover as
necessary.
2. Improper bolt tightening
procedure.2. Tighten clutch cover using proper
procedure.
Facing on flywheel side of disc torn,
gouged, or worn.1. Flywheel surface scored or
nicked.1. Correct surface condition if
possible. Replace flywheel and disc
as necessary.
2. Clutch disc sticking or binding on
transmission input shaft.2. Inspect components and
correct/replace as necessary.
Clutch disc facing burnt. Flywheel
and cover pressure plate surfaces
heavily glazed.1. Frequent operation under high
loads or hard acceleration
conditions.1. Correct condition of flywheel and
pressure plate surface. Replace
clutch cover and disc. Alert driver to
problem cause.
2. Driver frequently rides (slips)
clutch. Results in rapid wear and
overheating of disc and cover.2. Correct condition of flywheel and
pressure plate surface. Replace
clutch cover and disc. Alert driver to
problem cause.
Clutch disc binds on input shaft
splines.1. Clutch disc hub splines damaged
during installation.1. Clean, smooth, and lubricate hub
splines if possible. Replace disc if
necessary.
2. Input shaft splines rough,
damaged, or corroded.2. Clean, smooth, and lubricate
shaft splines if possible. Replace
input shaft if necessary.
Clutch disc rusted to flywheel and/or
pressure plate.1. Clutch not used for an extended
period of time (e.g. long term
vehicle storage).1. Sand rusted surfaces with 180
grit sanding paper. Replace clutch
cover and flywheel if necessary.
DRCLUTCH 6 - 3
CLUTCH (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
Partial engagement of clutch disc.
One side of disc is worn and the
other side is glazed and lightly
worn.1. Clutch pressure plate position
incorrect.1. Replace clutch disc and cover.
2. Clutch cover, spring, or release
fingers bent or distorted.2. Replace clutch disc and cover.
3. Clutch disc damaged or
distorted.2. Replace clutch disc.
4. Clutch misalignment. 4. Check alignment and runout of
flywheel, disc, pressure plate, andùr
clutch housing. Correct as
necessary.
SPECIFICATIONS
TORQUE SPECIFICATIONS
DESCRIPTION N´m Ft. Lbs. In. Lbs.
Slave Cylinder Nuts 23 17 -
Clutch Master Cylinder
Nuts28 21 -
Pressure Plate Bolts - V6
&V850 37 -
Pressure Plate Bolts - V10 30 22.5 -
Pressure Plate Bolts -
Diesel30 22.5 -
Release Bearing Pivot 23 17 -
Flywheel Bolts 95 70 -
CLUTCH DISC
REMOVAL
(1) Support engine with wood block and adjustable
jack stand, to prevent strain on engine mounts.
(2) Remove transmission and transfer case, if
equipped.
(3) If pressure plate will be reused, mark the posi-
tion on flywheel with paint or scriber (Fig. 1). Also
note location marks on the pressure next to the bolt
holes. The mark will be a L or a circle with an X in
it.
(4) Insert clutch alignment tool through clutch disc
and into pilot bushing, to hold disc in place while
removing bolts.
(5) Loosen pressure plate bolts evenly, a few
threads at a time and in a diagonal pattern to pre-
vent warping the plate.
(6) Remove bolts completely and remove pressure
plate, disc and alignment tool.
INSTALLATION
(1) Check runout and free operation of new clutch
disc.
(2) Lubricate crankshaft pilot bearing with a NLGI
- 2 rated grease.
(3) Install clutch alignment tool in clutch disc hub
with the raised side of hub is facing away from the
flywheel.
NOTE: Flywheel side is imprinted on the disc face.
(4) Install alignment tool in pilot bearing and posi-
tion disc on the flywheel.
(5) Position pressure plate over disc and onto the
flywheel (Fig. 2).
(6) Align and hold pressure plate in position and
install bolts finger tight.
(7) Tighten bolts evenly and a few threads at a
time in a diagonal pattern.
CAUTION: Bolts must be tightened evenly and to
specified torque to avoid warping pressure plate
cover.
DRCLUTCH 6 - 5
CLUTCH (Continued)

(8) Tighten pressure plate bolts to:
²V6 & V8 Engines - 50 N´m (37 ft. lbs.)
²V10 & Diesel Engines - 30 N´m (22.5 ft. lbs.)
(9) Remove release lever and release bearing from
clutch housing. Apply Mopar high temperature bear-
ing grease to bore of release bearing, release lever
contact surfaces and release lever pivot stud (Fig. 3).
(10) Apply light coat of Mopar high temperature
bearing grease to splines of transmission input shaft
and to release bearing slide surface of the transmis-
sion front bearing retainer (Fig. 4).CAUTION: Do not over lubricate shaft splines. This
can result in grease contamination of the disc.
Fig. 1 PRESSURE PLATE POSITION-TYPICAL
1 - FLYWHEEL
2 - ALIGNMENT MARKS
3 - PRESSURE PLATE
Fig. 2 CLUTCH DISC AND PRESSURE PLATE
1 - FLYWHEEL
2 - PRESSURE PLATE AND DISC
3 - ALIGNMENT TOOL
Fig. 3 LUBRICATION POINTS
1 - CLUTCH HOUSING
2 - FORK PIVOT BALL
3 - RELEASE FORK
4 - RELEASE BEARING BORE
5 - LUBE POINTS
Fig. 4 INPUT SHAFT LUBRICATION POINTS
1 - INPUT SHAFT
2 - BEARING RETAINER
3 - SPLINE AND RELEASE BEARING SURFACE
6 - 6 CLUTCHDR
CLUTCH DISC (Continued)

(11) Wipe pilot bearing surface clean.
(12) Install release lever and bearing in clutch
housing. Verify spring clips that retain fork on pivot
ball and release bearing on fork are installed prop-
erly (Fig. 5).
NOTE: If release lever is installed correctly, the
lever part number will be toward the bottom of the
transmission and right side up. There is also a
stamped ªIº in the lever which goes to the pivot ball
side of the transmission.
(13) Install transmission and transfer case if
equipped.
(14) Check fluid level in clutch master cylinder.
CLUTCH HOUSING
DIAGNOSIS AND TESTING
The clutch housing maintains alignment between
the crankshaft and transmission input shaft. Mis-
alignment can cause clutch noise, hard shifting,
incomplete release and chatter. Also premature pilot
bearing, cover release fingers and clutch disc wear.
In severe cases, it can cause premature wear of the
transmission input shaft and front bearing.
NOTE: Only the NV4500 clutch housing can be
checked using the following bore and face runout
procedures. The NV5600 clutch housing is a inte-
gral part of the transmission and can only be
checked off the vehicle.
CLUTCH HOUSING BORE RUNOUT
CAUTION: On diesel engines if housing bore runout
exceeds 0.015 inch, the clutch housing/transmis-
sion adapter plate must be replaced. On gas
engines if housing bore runout exceeds 0.053 in.
the clutch housing must be replaced.
NOTE: Offset dowels are available for gas engines
to correct housing bore runout. They are not avail-
able for diesel engines.
(1) Remove the clutch housing.
(2) Remove the clutch cover and disc.
(3) Replace one of the flywheel bolts with an
appropriate size threaded rod that is 10 in. (25.4 cm)
long (Fig. 6). The rod will be used to mount the dial
indicator.
(4) Remove release fork from the clutch housing.
(5) Install clutch housing. Tighten the housing
bolts nearest the alignment dowels first.
(6) Mount dial indicator on the threaded rod and
position indicator plunger on the clutch housing bore
(Fig. 7).
(7) Rotate crankshaft until indicator plunger is at
the topof the housing bore. Zero the indicator at this
point.
(8) Rotate crankshaft and record indicator read-
ings at eight points (45É apart) around the bore (Fig.
8). Take measurement at least twice for accuracy.
(9) Subtract each reading from the one 180É oppo-
site to determine runout and direction. Bore runout
example (Fig. 8):
²0.000 ± (±0.007) = 0.007 in.
²+0.002 ± (±0.010) = 0.012 in.
²+0.004 ± (±0.005) = 0.009 in.
²±0.001 ± (+0.001) = ±0.002 in.
Fig. 5 FORK, BEARING AND SPRING CLIPS
1 - FORK
2 - SPRING CLIP
3 - BEARING
4 - SPRING CLIP
Fig. 6 DIAL INDICATOR MOUNTING STUD
1 - 7/16 - 20 THREAD
2 - NUT
3 - STUD OR THREADED ROD
4 - 10 INCHES LONG
DRCLUTCH 6 - 7
CLUTCH DISC (Continued)

(3) Disconnect release bearing from release fork
and remove bearing (Fig. 15).
INSTALLATION
(1) Inspect bearing slide surface on transmission
front bearing retainer. Replace retainer if slide sur-
face is scored, worn, or cracked.
(2) Inspect release lever and pivot stud. Be sure
stud is secure and in good condition. Be sure fork is
not distorted or worn. Replace fork spring clips if
bent or damaged.
(3) Lubricate input shaft splines, bearing retainer
slide surface, lever pivot ball stud, and release lever
pivot surface with Moparthigh temperature bearing
grease.
(4) Install release fork and release bearing (Fig.
16). Be sure fork and bearing are properly secured by
spring clips. Also be sure that the release fork is
installed properly. The rear side of the release lever
has one end with a raised area. This raised area goes
toward the slave cylinder side of the transmission.
(5) Install clutch housing, if removed.
(6) Install transmission and transfer case.(7) Check clutch master cylinder fluid level.
FLYWHEEL
DIAGNOSIS AND TESTING
Check flywheel runout whenever misalignment is
suspected. Flywheel runout should not exceed 0.08
mm (0.003 in.). Measure runout at the outer edge of
the flywheel face with a dial indicator. Mount the
indicator on a stud installed in place of one of the fly-
wheel bolts.
Fig. 14 CLUTCH HOUSING - NV4500
1 - ENGINE BLOCK
2 - CLUTCH DISC/PRESSURE PLATE
3 - CLUTCH HOUSING
4 - DUST COVER
Fig. 15 CLUTCH RELEASE COMPONENTS
1 - CONED WASHER
2 - CLUTCH HOUSING
3 - RELEASE FORK
4 - RELEASE BEARING AND SLEEVE
5 - PIVOT 23 N´m (200 IN. LBS.)
6 - SPRING CLIP
Fig. 16 Clutch Release Fork And
1 - PIVOT BALL
2 - FORK
3 - SLAVE CYLINDER OPENING
4 - BEARING
6 - 10 CLUTCHDR
CLUTCH RELEASE BEARING (Continued)

Common causes of runout are:
²heat warpage
²improper machining
²incorrect bolt tightening
²improper seating on crankshaft flange shoulder
²foreign material on crankshaft flange
Flywheel machining is not recommended. The fly-
wheel clutch surface is machined to a unique contour
and machining will negate this feature. Minor fly-
wheel scoring can be cleaned up by hand with 180
grit emery or with surface grinding equipment.
Remove only enough material to reduce scoring
(approximately 0.001 - 0.003 in.). Heavy stock
removal isnot recommended.Replace the flywheel
if scoring is severe and deeper than 0.076 mm (0.003
in.). Excessive stock removal can result in flywheel
cracking or warpage after installation; it can also
weaken the flywheel and interfere with proper clutch
release.
Clean the crankshaft flange before mounting the
flywheel. Dirt and grease on the flange surface may
cock the flywheel causing excessive runout. Use new
bolts when remounting a flywheel and secure the
bolts with Mopar Lock And Seal or equivalent.
Tighten flywheel bolts to specified torque only. Over-
tightening can distort the flywheel hub causing
runout.
REMOVAL
(1) Remove transmission.
(2) Remove pressure plate and clutch.
(3) Remove flywheel bolts and remove flywheel.
DISASSEMBLY
NOTE: If the teeth are worn or damaged, the fly-
wheel should be replaced as an assembly. This is
the recommended repair. In cases where a new fly-
wheel is not readily available, (V10/Diesel Engine
only) a replacement ring gear can be installed. The
following procedure must be observed to avoid
damaging the flywheel and replacement gear.
WARNING: WEAR PROTECTIVE GOGGLES OR
SAFETY GLASSES WHILE CUTTING RING GEAR.
(1) Mark position of the old gear for alignment ref-
erence on the flywheel. Use a scriber for this pur-
pose.
(2) Remove the old gear by cutting most of the way
through it (at one point) with an abrasive cut-off
wheel. Then complete removal with a cold chisel or
punch.
ASSEMBLY
NOTE: The ring gear is a shrink fit on the flywheel.
This means the gear must be expanded by heating
in order to install it. The method of heating and
expanding the gear is extremely important. Every
surface of the gear must be heated at the same
time to produce uniform expansion. An oven or
similar enclosed heating device must be used. Tem-
perature required for uniform expansion is approxi-
mately 375É F.
CAUTION: Do not use an oxy/acetylene torch to
remove the old gear, or to heat and expand a new
gear. The high temperature of the torch flame can
cause localized heating that will damage the fly-
wheel. In addition, using the torch to heat a replace-
ment gear will cause uneven heating and
expansion. The torch flame can also anneal the
gear teeth resulting in rapid wear and damage after
installation.
WARNING: WEAR PROTECTIVE GOGGLES OR
SAFETY GLASSES AND HEAT RESISTENT GLOVES
WHEN HANDLING A HEATED RING GEAR.
(1) The heated gear must be installed evenly to
avoid misalignment or distortion.
(2)
Position and install the heated ring gear on the
flywheel with a shop press and a suitable press plates.
(3) Place flywheel on work bench and let it cool in
normal shop air. Allow the ring gear to cool down
completely before installation it on the engine.
CAUTION: Do not use water or compressed air to
cool the flywheel. The rapid cooling produced by
water or compressed air will distort or crack the
new gear.
INSTALLATION
(1) Install flywheel on the crank shaft.
(2) Install flywheel bolts and tighten to 95 N´m
(70 ft. lbs.).
(3) Install clutch.
(4) Install transmission.
PILOT BEARING
REMOVAL
(1) Remove transmission.
(2) Remove clutch disc.
(3) Use a suitable blind hole puller to remove pilot
bearing.
DRCLUTCH 6 - 11
FLYWHEEL (Continued)

²Engine loads and temperatures are high such as
when towing a trailer.
²Cool silicone fluid within the fan drive unit is
being redistributed back to its normal disengaged
(warm) position. This can occur during the first 15
seconds to one minute after engine start-up on a cold
engine.
LEAKS
Viscous fan drive operation is not affected by small
oil stains near the drive bearing. If leakage appears
excessive, replace the fan drive unit.
VISCOUS DRIVE
If the fan assembly free-wheels without drag (the
fan blades will revolve more than five turns when
spun by hand), replace the fan drive. This spin test
must be performed when the engine is cool.
For the following test, the cooling system must be
in good condition. It also will ensure against exces-
sively high coolant temperature.
WARNING: BE SURE THAT THERE IS ADEQUATE
FAN BLADE CLEARANCE BEFORE DRILLING.
(1) Drill a 3.18-mm (1/8-in) diameter hole in the
top center of the fan shroud.
(2) Obtain a dial thermometer with an 8 inch stem
(or equivalent). It should have a range of -18É-to-
105ÉC (0É-to-220É F). Insert thermometer through the
hole in the shroud. Be sure that there is adequate
clearance from the fan blades.
(3) Connect a tachometer and an engine ignition
timing light. The timing light is to be used as a
strobe light. This step cannot be used on the diesel
engine.(4) Block the air flow through the radiator. Secure
a sheet of plastic in front of the radiator. Use tape at
the top to secure the plastic and be sure that the air
flow is blocked.
(5) Be sure that the air conditioner (if equipped)
and blowe fan is turned off.
WARNING: USE EXTREME CAUTION WHEN THE
ENGINE IS OPERATING. DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR
HANDS NEAR THE PULLEYS, BELTS OR FAN. DO
NOT WEAR LOOSE CLOTHING.
(6) Start the engine and operate at 2400 rpm.
Within ten minutes the air temperature (indicated on
the dial thermometer) should be up to 88É C (190É F).
Fan driveengagementshould start to occur at/be-
tween:
²3.7L Automatic - 93É C - 99ÉC (200É F - 210É F)
²3.7L Manual/4.7L Automatic/5.9L - 85É - 91É C
(185É - 195É F)
²4.7L Manual - 74É - 79É C (165É - 175É F)
²5.7L
²5.9L
²Engagement is distinguishable by a definite
increasein fan flow noise (roaring). The timing light
also will indicate an increase in the speed of the fan.
(7) When viscous drive engagement is verified,
remove the plastic sheet. Fan drivedisengagement
should start to occur at or between:
²3.7L Automatic - 76ÉC - 81ÉC (168É F - 178É F)
²3.7L Manual/4.7L Auto/ 5.9L - 67ÉC - 73ÉC (153É
F - 163É F)
²4.7L Manual - 56ÉC - 62ÉC (133É F - 143É F)
²5.7L
²5.9L
²8.0L engine - 93É to 101É C (190É - 205É F) Min-
imum 73ÉC (163ÉF). A definitedecreaseof fan flow
noise (roaring) should be noticed. If not, replace the
defective viscous fan drive unit.
CAUTION: Some engines equipped with serpentine
drive belts have reverse rotating fans and viscous
fan drives. They are marked with the word
REVERSE to designate their usage. Installation of
the wrong fan or viscous fan drive can result in
engine overheating.
Fig. 32 Viscous Fan Drive - Typical
1 - VISCOUS FAN DRIVE
2 - THERMOSTATIC SPRING
3 - MOUNTING NUT TO WATER PUMP HUB
DRENGINE 7 - 51
FAN DRIVE VISCOUS CLUTCH-GAS ENGINES (Continued)