1998 DODGE RAM 1500 Serpentine belt

INSTALLATION
(1) Install tensioner assembly to water inlet
bracket. A dowel is located on back of tensioner. Align
this dowel to hole in tensioner mounting bracket.
Tighten bolt to 43 N´m (32 ft. lbs.) torque.
(2) Install drive belt (Refer to 7 - COOLING/AC-
CESSORY DRIVE/DRIVE BELTS - INSTALLA-
TION).
DRIVE BELT - 3.7L / 4.7L
DIAGNOSIS AND TESTING - ACCESSORY
DRIVE BELT
VISUAL DIAGNOSIS
When diagnosing serpentine accessory drive belts,
small cracks that run across the ribbed surface of the
belt from rib to rib (Fig. 6), are considered normal.
These are not a reason to replace the belt. However,
cracks running along a rib (not across) arenotnor-
mal. Any belt with cracks running along a rib must
be replaced (Fig. 6). Also replace the belt if it has
excessive wear, frayed cords or severe glazing.
Refer to ACCESSORY DRIVE BELT DIAGNOSIS
CHART for further belt diagnosis.
NOISE DIAGNOSIS
Noises generated by the accessory drive belt are
most noticeable at idle. Before replacing a belt toresolve a noise condition, inspect all of the accessory
drive pulleys for alignment, glazing, or excessive end
play.
ACCESSORY DRIVE BELT DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
RIB CHUNKING (One or more ribs
has separated from belt body)1. Foreign objects imbedded in
pulley grooves.1. Remove foreign objects from
pulley grooves. Replace belt.
2. Installation damage 2. Replace belt
RIB OR BELT WEAR 1. Pulley misaligned 1. Align pulley(s)
2. Abrasive environment 2. Clean pulley(s). Replace belt if
necessary
3. Rusted pulley(s) 3. Clean rust from pulley(s)
4. Sharp or jagged pulley groove
tips4. Replace pulley. Inspect belt.
5. Belt rubber deteriorated 5. Replace belt
Fig. 6 Belt Wear Patterns
1 - NORMAL CRACKS BELT OK
2 - NOT NORMAL CRACKS REPLACE BELT
7 - 24 ACCESSORY DRIVEDR
BELT TENSIONER - 5.9L DIESEL (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
CORD EDGE FAILURE
(Tensile member exposed at edges
of belt or separated from belt body)1. Incorrect belt tension 1. Inspect/Replace tensioner if
necessary
2. Belt contacting stationary object 2. Replace belt
3. Pulley(s) out of tolerance 3. Replace pulley
4. Insufficient adhesion between
tensile member and rubber matrix4. Replace belt
REMOVAL
CAUTION: DO NOT LET TENSIONER ARM SNAP
BACK TO THE FREEARM POSITION, SEVER DAM-
AGE MAY OCCUR TO THE TENSIONER.
Belt tension is not adjustable. Belt adjustment is
maintained by an automatic (spring load) belt ten-
sioner.
(1) Disconnect negative battery cable from battery.
(2) Rotate belt tensioner until it contacts it's stop.
Remove belt, then slowly rotate the tensioner into
the freearm position. (Fig. 7).
INSTALLATION
Belt tension is not adjustable. Belt adjustment is
maintained by an automatic ( spring load ) belt ten-
sioner.
(1) Check condition of all pulleys.
CAUTION: When installing the serpentine accessory
drive belt, the belt MUST be routed correctly. If not,
the engine may overheat due to the water pump
rotating in the wrong direction (Fig. 7).
(2) Install new belt (Fig. 7). Route the belt around
all pulleys except the idler pulley. Rotate the ten-
sioner arm until it contacts it's stop position. Route
the belt around the idler and slowly let the tensioner
rotate into the belt. Make sure the belt is seated onto
all pulleys.
(3) With the drive belt installed, inspect the belt
wear indicator (Fig. 8). On 4.7L Engines only, the gap
between the tang and the housing stop (measure-
ment A) must not exceed 24 mm (.94 inches). If the
measurement exceeds this specification replace the
serpentine accessory drive belt.
Fig. 7 BELT ROUTING 3.7L / 4.7L
1 - GENERATOR PULLEY
2 - ACCESSORY DRIVE BELT
3 - POWER STEERING PUMP PULLEY
4 - CRANKSHAFT PULLEY
5 - IDLER PULLEY
6 - TENSIONER
7 - A/C COMPRESSOR PULLEY
8 - WATER PUMP PULLEY
Fig. 8 Accessory Drive Belt Wear Indicator±4.7L
Engine
1 - AUTOMATIC TENSIONER ASSEMBLY
7 - 26 ACCESSORY DRIVEDR
DRIVE BELT - 3.7L / 4.7L (Continued)

DRIVE BELT - 5.9L DIESEL
DIAGNOSIS AND TESTINGÐACCESSORY
DRIVE BELT
VISUAL DIAGNOSIS
When diagnosing serpentine accessory drive belts,
small cracks that run across the ribbed surface of the
belt from rib to rib (Fig. 9), are considered normal.
These are not a reason to replace the belt. However,
cracks running along a rib (not across) arenotnor-
mal. Any belt with cracks running along a rib must
be replaced (Fig. 9). Also replace the belt if it has
excessive wear, frayed cords or severe glazing.
Refer to ACCESSORY DRIVE BELT DIAGNOSIS
CHART for further belt diagnosis.
NOISE DIAGNOSIS
Noises generated by the accessory drive belt are
most noticeable at idle. Before replacing a belt to
resolve a noise condition, inspect all of the accessory
drive pulleys for alignment, glazing, or excessive end
play.
ACCESSORY DRIVE BELT DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
RIB CHUNKING (One or more ribs
has separated from belt body)1. Foreign objects imbedded in
pulley grooves.1. Remove foreign objects from
pulley grooves. Replace belt.
2. Installation damage 2. Replace belt
RIB OR BELT WEAR 1. Pulley misaligned 1. Align pulley(s)
2. Abrasive environment 2. Clean pulley(s). Replace belt if
necessary
3. Rusted pulley(s) 3. Clean rust from pulley(s)
4. Sharp or jagged pulley groove
tips4. Replace pulley. Inspect belt.
5. Belt rubber deteriorated 5. Replace belt
BELT SLIPS 1. Belt slipping because of
insufficient tension1. Inspect/Replace tensioner if
necessary
2. Belt or pulley exposed to
substance that has reduced friction
(belt dressing, oil, ethylene glycol)2. Replace belt and clean pulleys
3. Driven component bearing failure
(seizure)3. Replace faulty component or
bearing
4. Belt glazed or hardened from
heat and excessive slippage4. Replace belt.
Fig. 9 Belt Wear Patterns
1 - NORMAL CRACKS BELT OK
2 - NOT NORMAL CRACKS REPLACE BELT
DRACCESSORY DRIVE 7 - 27

(4)Do Notattempt to remove the fan/viscous fan
drive assembly from the vehicle at this time.
(5)Do Notunbolt the fan blade assembly (Fig. 3)
from viscous fan drive at this time.
(6) Remove the fan shroud-to-radiator mounting
bolts.
(7) Pull the lower shroud mounts out of the radia-
tor tank clips.
(8) Remove the fan shroud and fan blade/viscous
fan drive assembly as a complete unit from vehicle.
(9) After removing the fan blade/viscous fan drive
assembly,do notplace the viscous fan drive in a
horizontal position. If stored horizontally, silicone
fluid in the viscous fan drive could drain into its
bearing assembly and contaminate lubricant.
CAUTION: Do not remove water pump pulley-to-wa-
ter pump bolts. This pulley is under spring tension.
(10) Remove four bolts securing fan blade assem-
bly to viscous fan drive (Fig. 3).
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.
CLEANING
Clean the fan blades using a mild soap and water.
Do not use an abrasive to clean the blades.
INSPECTION
WARNING: DO NOT ATTEMPT TO BEND OR
STRAIGHTEN FAN BLADES IF FAN IS NOT WITHIN
SPECIFICATIONS.
CAUTION: If fan blade assembly is replaced
because of mechanical damage, water pump and
viscous fan drive should also be inspected. These
components could have been damaged due to
excessive vibration.
INSTALLATION
(1) Install fan blade assembly to the viscous fan
drive. Tighten the bolts (Fig. 3) to 24 N´m (18 ft. lbs.)
torque.
(2) Position the fan shroud and the fan blade/vis-
cous fan drive assembly to the vehicle as a complete
unit.
(3) Install the fan shroud.
Fig. 2 Using Special Tool 6958 Spanner Wrench
1 - SPECIAL TOOL 6958 SPANNER WRENCH WITH ADAPTER
PINS 8346
2-FAN
Fig. 3 Fan Blade/Viscous Fan Drive - Gas Engines -
Typical
1 - WATER PUMP BYPASS HOSE
2 - FAN BLADE ASSEMBLY
3 - VISCOUS FAN DRIVE
4 - WATER PUMP AND PULLEY
5 - Bolts (4)
7 - 34 ENGINEDR
RADIATOR FAN - GAS ENGINES (Continued)

CAUTION: A number or letter is stamped into the
tongue of the constant tension clamps (Fig. 19). If
replacement is necessary, use only an original
equipment clamp with a matching number, letter
and width.
(7) Remove the radiator upper hose clamp and
upper hose at the thermostat housing.
(8) Position the wiring harness (behind thermostat
housing) to gain access to the thermostat housing.(9) Remove the thermostat housing mounting
bolts, thermostat housing, gasket and thermostat
(Fig. 20). Discard old gasket.
INSTALLATION
(1) Clean the mating areas of the intake manifold
and thermostat housing.
(2) Install the thermostat (spring side down) into
the recessed machined groove on the intake manifold
(Fig. 20).
(3) Install the gasket on the intake manifold and
over the thermostat (Fig. 20).
(4) Position the thermostat housing to the intake
manifold.Note:The word FRONT stamped on hous-
ing (Fig. 21). For adequate clearance, thismustbe
placed towards the front of the vehicle. The housing
is slightly angled forward after the installation to the
intake manifold.
(5) Install the housing-to-intake manifold bolts.
Tighten the bolts to 23 N´m (200 in. lbs.).
(6) Install the radiator upper hose to the thermo-
stat housing.
CAUTION: When installing the serpentine accessory
drive belt, the belt must be routed correctly. If not,
the engine may overheat due to the water pump
rotating in wrong direction. Refer to (Fig. 22) for the
correct 5.9L engine belt routing. The correct belt
with correct length must be used.
Fig. 18 Automatic Belt Tensioner ± 5.9L Engines
1 - IDLER PULLEY
2 - TENSIONER
3 - FAN BLADE
Fig. 19 SPRING CLAMP SIZE LOCATION
1 - SPRING CLAMP SIZE LOCATION
Fig. 20 Thermostat ± 5.9L Engines
1 - THERMOSTAT HOUSING
2 - GASKET
3 - INTAKE MANIFOLD
4 - THERMOSTAT
5 - MACHINED GROOVE
DRENGINE 7 - 43
ENGINE COOLANT THERMOSTAT- 5.7L (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)

The pressure cap may test properly while posi-
tioned on tool 7700 (or equivalent). It may not hold
pressure or vacuum when installed on the radiator. If
so, inspect the radiator filler neck and radiator cap's
top gasket for damage. Also inspect for dirt or distor-
tion that may prevent the cap from sealing properly.
CAUTION: Radiator pressure testing tools are very
sensitive to small air leaks which will not cause
cooling system problems. A pressure cap that does
not have a history of coolant loss should not be
replaced just because it leaks slowly when tested
with this tool. Add water to tool. Turn tool upside
down and recheck pressure cap to confirm that cap
needs replacement.
CLEANING
Use only a mild soap and water to clean the radi-
ator cap. Using any type of solvent may cause dam-
age to the seal in the radiator cap.
INSPECTION
Hold cap at eye level, right side up. The vent valve
(Fig. 42) at bottom of cap should closed. A slight
downward pull on the vent valve should open it. If
the rubber gasket has swollen and prevents vent
valve from opening, replace cap.
Hold cap at eye level, upside down. If any light can
be seen between vent valve and rubber gasket,
replace cap. A replacement cap must be the typedesigned for a coolant reserve/overflow system with a
completely sealed diaphragm spring and a rubber
gasket. This gasket is used to seal to radiator filler
neck top surface. Use of proper cap will allow coolant
return to radiator.
WATER PUMP - 3.7L/4.7L
DESCRIPTION
DESCRIPTION - WATER PUMP
A centrifugal water pump circulates coolant
through the water jackets, passages, intake manifold,
radiator core, cooling system hoses and heater core.
The pump is driven from the engine crankshaft by a
single serpentine drive belt.
The water pump impeller is pressed onto the rear
of a shaft that rotates in bearings pressed into the
housing. The housing has two small holes to allow
seepage to escape. The water pump seals are lubri-
cated by the antifreeze in the coolant mixture. No
additional lubrication is necessary.
Both heater hoses are connected to fittings on the
timing chain front cover. The water pump is also
mounted directly to the timing chain cover and is
equipped with a non serviceable integral pulley (Fig.
43).
DESCRIPTION - WATER PUMP BYPASS
The 3.7L and 4.7L engine uses an internal water/
coolant bypass system. The design uses galleries in
the timing chain cover to circulate coolant during
Fig. 41 Pressure Testing Radiator Cap - Typical
1 - PRESSURE CAP
2 - TYPICAL COOLING SYSTEM PRESSURE TESTER
Fig. 42 Radiator Pressure Cap
1 - STAINLESS-STEEL SWIVEL TOP
2 - RUBBER SEALS
3 - VENT VALVE
4 - RADIATOR TANK
5 - FILLER NECK
6 - OVERFLOW NIPPLE
7 - MAIN SPRING
8 - GASKET RETAINER
DRENGINE 7 - 59
RADIATOR PRESSURE CAP (Continued)

(3) Spin the water pump to be sure that the pump
impeller does not rub against the timing chain case/
cover.
(4) Connect the radiator lower hose to the water
pump.
(5) Relax the tension from the belt tensioner (Fig.
46). Install the drive belt (Refer to 7 - COOLING/AC-
CESSORY DRIVE/DRIVE BELTS - INSTALLA-
TION).
CAUTION: When installing the serpentine accessory
drive belt, the belt must be routed correctly. If not,
the engine may overheat due to the water pump
rotating in the wrong direction. Refer to (Fig. 48) for
the correct belt routing. Or, refer to the Belt Routing
Label located in the engine compartment. The cor-
rect belt with correct length must be used.
(6) Install the radiator fan (Refer to 7 - COOLING/
ENGINE/RADIATOR FAN - INSTALLATION).
(7) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(8) Connect the negative battery cable.
(9) Start and warm the engine. Check for leaks.WATER PUMP - 5.9L DIESEL
DESCRIPTION
The water pump is mounted to the front of the
engine block between the automatic belt tensioner
and the fan drive pulley.
The water pump impeller is pressed onto the rear
of a shaft that rotates in a bearing pressed into the
water pump body. The body has a small hole for ven-
tilation. The water pump seals are lubricated by
antifreeze in the coolant mixture. Additional lubrica-
tion is not necessary.
OPERATION
The diesel engine water pump draws coolant from
the radiator outlet and circulates it through engine,
heater core and back to radiator inlet. The crank-
shaft pulley drives the water pump with a serpentine
drive belt.
DIAGNOSIS AND TESTINGÐWATER PUMP
A quick test to determine if pump is working is to
check if heater warms properly. A defective water
pump will not be able to circulate heated coolant
through the long heater hose to the heater core.
REMOVAL
(1) Disconnect battery negative cables.
(2) Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(3) Remove the accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(4) Remove water pump mounting bolts (Fig. 49).
(5) Clean water pump sealing surface on cylinder
block.
CLEANING
Clean gasket mating surfaces as necessary.
INSPECTION
Visually inspect the water pump and replace if it
has any of the following conditions:
²The body is cracked or damaged
²Water leaks from the shaft seal. This is evident
by traces of coolant below the vent hole
²Loose or rough turning bearing.
²Impeller rubbing the pump body
INSTALLATION
(1) Install new O-ring seal in groove on water
pump (Fig. 50).
(2) Install water pump with the weep hole facing
downward. Tighten mounting bolts to 24 N´m (18 ft.
lbs.) torque.
Fig. 48 Belt Routing 3.7L
1 - GENERATOR PULLEY
2 - ACCESSORY DRIVE BELT
3 - POWER STEERING PUMP PULLEY
4 - CRANKSHAFT PULLEY
5 - IDLER PULLEY
6 - TENSIONER
7 - A/C COMPRESSOR PULLEY
8 - WATER PUMP PULLEY
7 - 62 ENGINEDR
WATER PUMP - 3.7L/4.7L (Continued)