1998 DODGE RAM 1500 Removal

INSTALLATION
(1) Install tensioner on to the mounting bracket.
Tighten bolt to 41 N´m (30 ft. lbs.).
(2) Install tensioner and bracket assembly
(3) Install accessory drive belt (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/DRIVE BELTS - INSTAL-
LATION).
BELT TENSIONER - 5.9L
DIESEL
DESCRIPTION
Drive belts on all engines are equipped with a
spring loaded automatic belt tensioner (Fig. 4). This
tensioner maintains constant belt tension at all times
and requires no maintenance or adjustment.
CAUTION: Do not attempt to check belt tension with
a belt tension gauge on vehicles equipped with an
automatic belt tensioner.
OPERATION
WARNING: THE AUTOMATIC BELT TENSIONER
ASSEMBLY IS SPRING LOADED. DO NOT ATTEMPT
TO DISASSEMBLE THE TENSIONER ASSEMBLY.
The automatic belt tensioner maintains correct belt
tension using a coiled spring within the tensioner
housing. The spring applies pressure to the tensioner
arm pressing the arm into the belt, tensioning the
belt.
REMOVAL
WARNING: BECAUSE OF HIGH SPRING PRES-
SURE, DO NOT ATTEMPT TO DISASSEMBLE AUTO-
MATIC TENSIONER. UNIT IS SERVICED AS AN
ASSEMBLY.
(1) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(2) Remove tensioner mounting bolt (Fig. 5) and
remove tensioner.
Fig. 4 Accessory Drive Belt - 5.9L Diesel
1 - GENERATOR
2 - WATER PUMP
3 - IDLER
4 - POWER STEERING PUMP
5 - RADIATOR FAN PULLEY
6 - CRANKSHAFT
7 - AUTOMATIC TENSIONER
8 - A/C COMPRESSOR
Fig. 5 AUTOMATIC BELT TENSIONER 5.9L DIESEL
ENGINE
1 - GENERATOR
2 - WATER PUMP
3 - IDLER
4 - POWER STEERING PUMP
5 - RADIATOR FAN PULLEY
6 - CRANKSHAFT
7 - AUTOMATIC TENSIONER
8 - A/C COMPRESSOR
DRACCESSORY DRIVE 7 - 23
BELT TENSIONER-5.7L (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)

REMOVAL
CAUTION: Do not attempt to check belt tension with
a belt tension gauge on vehicles equipped with an
automatic belt tensioner. Refer to Automatic Belt
Tensioner in this group.
NOTE: The belt routing schematics are published
from the latest information available at the time of
publication. If anything differs between these sche-
matics and the Belt Routing Label, use the sche-
matics on Belt Routing Label.This label is located in
the engine compartment.
Drive belts on diesel engines are equipped with a
spring loaded automatic belt tensioner.
This belt tensioner will be used on all belt config-
urations, such as with or without air conditioning.
For more information, (Refer to 7 - COOLING/AC-
CESSORY DRIVE/BELT TENSIONERS - DESCRIP-
TION).
(1) A 1/2 inch square hole is provided in the auto-
matic belt tensioner. Attach a 1/2 inch drive-long
handle ratchet to this hole.(2) Rotate ratchet and tensioner assembly clock-
wise (as viewed from front) until tension has been
relieved from belt.
(3) Remove belt from water pump pulley first.
(4) Remove belt from vehicle.
INSTALLATION
CAUTION: When installing the accessory drive belt,
the belt must be routed correctly. If not, engine may
overheat due to water pump rotating in wrong
direction. Refer to (Fig. 10) or (Fig. 11)for correct
engine belt routing. The correct belt with correct
length must be used.
(1) Position drive belt over all pulleysexcept
water pump pulley.
(2) Attach a 1/2 inch ratchet to tensioner.
(3) Rotate ratchet and belt tensioner clockwise.
Place belt over water pump pulley. Let tensioner
rotate back into place. Remove ratchet. Be sure belt
is properly seated on all pulleys.
Fig. 10 Belt Routing ± 5.9L Diesel Engine With A/C
1 - GENERATOR PULLEY
2 - WATER PUMP PULLEY
3 - IDLER PULLEY
4 - POWER STEERING PUMP PULLEY
5 - RADIATOR FAN PULLEY
6 - CRANKSHAFT PULLEY
7 - AUTOMATIC TENSIONER
8 - A/C COMPRESSOR PUMP PULLEY
Fig. 11 Belt Routing - 5.9L Diesel Engine Without
A/C
1 - GENERATOR PULLEY
2 - WATER PUMP PULLEY
3 - IDLER PULLEY
4 - POWER STEERING PUMP PULLEY
5 - RADIATOR FAN PULLEY
6 - CRANKSHAFT PULLEY
7 - AUTOMATIC TENSIONER
DRACCESSORY DRIVE 7 - 29
DRIVE BELT - 5.9L DIESEL (Continued)

ENGINE
TABLE OF CONTENTS
page page
COOLANT
DESCRIPTION
DESCRIPTION - ENGINE COOLANT.......31
DESCRIPTION - HOAT COOLANT.........32
OPERATION...........................33
COOLANT RECOVERY CONTAINER- GAS
ENGINES
DESCRIPTION.........................33
OPERATION...........................33
REMOVAL.............................33
INSTALLATION.........................33
RADIATOR FAN - GAS ENGINES
REMOVAL.............................33
CLEANING............................34
INSPECTION..........................34
INSTALLATION.........................34
RADIATOR FAN - 5.9L DIESEL
REMOVAL.............................35
CLEANING............................35
INSPECTION..........................35
INSTALLATION.........................36
ENGINE BLOCK HEATER
DESCRIPTION.........................36
OPERATION...........................36
DIAGNOSIS AND TESTING - ENGINE BLOCK
HEATER ............................36
REMOVAL.............................37
INSTALLATION.........................37
ENGINE BLOCK HEATER - 5.9L DIESEL
DESCRIPTION.........................37
OPERATION...........................38
REMOVAL.............................38
INSTALLATION.........................38
ENGINE COOLANT TEMPERATURE SENSOR
DESCRIPTION.........................38
OPERATION...........................38
REMOVAL.............................39
INSTALLATION.........................41
ENGINE COOLANT THERMOSTAT- 5.7L
DESCRIPTION.........................41
OPERATION...........................41
DIAGNOSIS AND TESTINGÐTHERMOSTAT . . . 42
REMOVAL.............................42
INSTALLATION.........................43
ENGINE COOLANT THERMOSTAT - 3.7L/4.7L
DESCRIPTION.........................44
OPERATION...........................44
DIAGNOSIS AND TESTINGÐTHERMOSTAT . . . 44
REMOVAL.............................45INSTALLATION.........................45
ENGINE COOLANT THERMOSTAT - 5.9L
DIESEL
DESCRIPTION.........................46
OPERATION...........................46
DIAGNOSIS AND TESTING - THERMOSTAT . . . 47
REMOVAL.............................47
INSTALLATION.........................47
ENGINE COOLANT THERMOSTAT - 8.0L
DESCRIPTION.........................48
OPERATION...........................48
DIAGNOSIS AND TESTING - THERMOSTAT . . . 48
REMOVAL.............................49
INSTALLATION.........................49
FAN DRIVE VISCOUS CLUTCH-GAS ENGINES
DESCRIPTION.........................50
OPERATION...........................50
DIAGNOSIS AND TESTING - VISCOUS FAN
DRIVE..............................50
FAN DRIVE VISCOUS CLUTCH - 5.9L DIESEL
DESCRIPTION.........................52
OPERATION...........................52
DIAGNOSIS AND TESTING -
ELECTRONICALLY CONTROLLED VISCOUS
FAN DRIVE..........................52
RADIATOR-3.7L/4.7L/5.7L
DESCRIPTION.........................54
OPERATION...........................54
DIAGNOSIS AND TESTING - RADIATOR
COOLANT FLOW......................54
REMOVAL.............................54
CLEANING............................55
INSPECTION..........................55
INSTALLATION.........................55
RADIATOR - 5.9L DIESEL
DESCRIPTION.........................56
OPERATION...........................56
DIAGNOSIS AND TESTING - RADIATOR
COOLANT FLOW......................56
REMOVAL.............................56
CLEANING............................56
INSPECTION..........................56
INSTALLATION.........................57
RADIATOR PRESSURE CAP
DESCRIPTION.........................57
OPERATION...........................58
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - RADIATOR
CAP-TO-FILLER NECK SEAL.............58
7 - 30 ENGINEDR

DIAGNOSIS AND TESTING - RADIATOR
CAP................................58
CLEANING............................59
INSPECTION..........................59
WATER PUMP - 3.7L/4.7L
DESCRIPTION
DESCRIPTION - WATER PUMP...........59
DESCRIPTION - WATER PUMP BYPASS....59
OPERATION
OPERATIONÐWATER PUMP............60
OPERATION - WATER PUMP BYPASS.....60
REMOVAL.............................60
CLEANING............................61
INSPECTION..........................61
INSTALLATION.........................61
WATER PUMP - 5.9L DIESEL
DESCRIPTION.........................62OPERATION...........................62
DIAGNOSIS AND TESTINGÐWATER PUMP . . . 62
REMOVAL.............................62
CLEANING............................62
INSPECTION..........................62
INSTALLATION.........................62
WATER PUMP - 5.7L
REMOVAL.............................63
INSTALLATION.........................63
WATER PUMP - 8.0L
DIAGNOSIS AND TESTING - WATER PUMP . . . 63
REMOVAL.............................64
CLEANING............................66
INSPECTION..........................66
INSTALLATION.........................66
COOLANT
DESCRIPTION
DESCRIPTION - ENGINE COOLANT
ETHYLENE-GLYCOL MIXTURES
CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethyl-
ene-glycol.
The use of aluminum cylinder blocks, cylinder
heads and water pumps requires special corrosion
protection. Only MopartAntifreeze/Coolant, 5
year/100,000 Mile Formula (ethylene-glycol base cool-
ant with corrosion inhibitors called HOAT, for Hybrid
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% distilled water to obtain a freeze
point of -37ÉC (-35ÉF).
The required ethylene-glycol (antifreeze) and water
mixture depends upon the climate and vehicle oper-
ating conditions. The antifreeze concentrationmust
alwaysbe a minimum of 44 percent, year-round in
all climates.If percentage is lower than 44 per-
cent, engine parts may be eroded by cavitation,
and cooling system components may be
severely damaged by corrosion.Maximum protec-
tion against freezing is provided with a 68% anti-
freeze concentration, which prevents freezing down to
-67.7É C (-90É F). A higher percentage will freeze at a
warmer temperature. Also, a higher percentage of
antifreeze can cause the engine to overheat becausethe specific heat of antifreeze is lower than that of
water.
Use of 100 percent ethylene-glycol will cause for-
mation of additive deposits in the system, as the cor-
rosion inhibitive additives in ethylene-glycol require
the presence of water to dissolve. The deposits act as
insulation, causing temperatures to rise to as high as
149É C (300É F). This temperature is hot enough to
melt plastic and soften solder. The increased temper-
ature can result in engine detonation. In addition,
100 percent ethylene-glycol freezes at 22É C (-8É F ).
PROPYLENE-GLYCOL MIXTURES
It's overall effective temperature range is smaller
than that of ethylene-glycol. The freeze point of 50/50
propylene-glycol and water is -32É C (-26É F). 5É C
higher than ethylene-glycol's freeze point. The boiling
point (protection against summer boil-over) of propy-
lene-glycol is 125É C (257ÉF)at96.5 kPa (14 psi),
compared to 128É C (263É F) for ethylene-glycol. Use
of propylene-glycol can result in boil-over or freeze-up
on a cooling system designed for ethylene-glycol. Pro-
pylene glycol also has poorer heat transfer character-
istics than ethylene glycol. This can increase cylinder
head temperatures under certain conditions.
Propylene-glycol/ethylene-glycol Mixtures can
cause the destabilization of various corrosion inhibi-
tors, causing damage to the various cooling system
components. Also, once ethylene-glycol and propy-
lene-glycol based coolants are mixed in the vehicle,
conventional methods of determining freeze point will
not be accurate. Both the refractive index and spe-
cific gravity differ between ethylene glycol and propy-
lene glycol.
DRENGINE 7 - 31

OPERATION
Coolant flows through the engine block absorbing
the heat from the engine, then flows to the radiator
where the cooling fins in the radiator transfers the
heat from the coolant to the atmosphere. During cold
weather the ethylene-glycol or propylene-glycol cool-
ant prevents water present in the cooling system
from freezing within temperatures indicated by mix-
ture ratio of coolant to water.
COOLANT RECOVERY
CONTAINER- GAS ENGINES
DESCRIPTION
The coolant reserve/overflow tank is mounted on
top of the fan shroud, and is made of high tempera-
ture plastic (Fig. 1).
OPERATION
The coolant reserve/overflow system works in con-
junction with the radiator pressure cap. It utilizes
thermal expansion and contraction of coolant to keep
coolant free of trapped air. It provides a volume for
expansion and contraction of coolant. It also provides
a convenient and safe method for checking coolant
level and adjusting level at atmospheric pressure.
This is done without removing the radiator pressure
cap. The system also provides some reserve coolantto the radiator to cover minor leaks and evaporation
or boiling losses.
As the engine cools, a vacuum is formed in the
cooling system of both the radiator and engine. Cool-
ant will then be drawn from the coolant tank and
returned to a proper level in the radiator.
REMOVAL
(1) Remove recovery hose from radiator.
(2) Remove the coolant container to fan shroud
mounting bolt.
(3) Tilt the container backward towards the engine
to disengage the mounting pin locking features and
lift the container away from the fan shroud (Fig. 1).
INSTALLATION
(1) Align the coolant container mounting pins into
the slots on the fan shroud and push the container
onto the fan shroud.
(2) Secure the container to the fan shroud with the
bolt. Tighten to 8.5N´m (75 in-lbs).
NOTE: Ensure that the locking feature on the
mounting pins has engaged.
(3) Connect the recovery hose to the radiator (Fig.
1).
RADIATOR FAN - GAS
ENGINES
REMOVAL
CAUTION: If the viscous fan drive is replaced
because of mechanical damage, the cooling fan
blades should also be inspected. Inspect for fatigue
cracks, loose blades, or loose rivets that could
have resulted from excessive vibration. Replace fan
blade assembly if any of these conditions are
found. Also inspect water pump bearing and shaft
assembly for any related damage due to a viscous
fan drive malfunction.
(1) Disconnect negative battery cable from battery.
(2) Remove coolant reserve/overflow container from
fan shroud and lay aside.Do Notdisconnect the
hoses or drain coolant from the container.
(3) The thermal viscous fan drive/fan blade assem-
bly is attached (threaded) to the water pump hub
shaft (Fig. 3). Remove the fan blade/viscous fan drive
assembly from the water pump by turning the
mounting nut counterclockwise as viewed from the
front. Threads on the viscous fan drive areRIGHT-
HAND.A 36 MM Fan Wrench should be used to pre-
vent pulley from rotating (Fig. 2).
Fig. 1 Coolant Recovery Bottle - Gas Engine
1 - SCREW
2 - COOLANT RECOVERY CONTAINER
3 - RADIATOR/RADIATOR CAP
4 - FAN SHROUD
DRENGINE 7 - 33
COOLANT (Continued)

(4) Install the fan blade/viscous fan drive assembly
to the water pump shaft (Fig. 3). Tighten mounting
nut to 50 N´m (37 ft. lbs.).
(5) Install the coolant reserve/overflow container
to the fan shroud.
(6) Connect the negative battery cable.
NOTE:
Viscous Fan Drive Fluid Pump Out Requirement:
After installing a new viscous fan drive, bring the
engine speed up to approximately 2000 rpm and
hold for approximately two minutes. This will
ensure proper fluid distribution within the drive.
RADIATOR FAN - 5.9L DIESEL
REMOVAL
CAUTION: If the electronically controlled viscous
fan drive is replaced because of mechanical dam-
age, the cooling fan blades should also be
inspected. Inspect for fatigue cracks, or chipped
blades that could have resulted from excessive
vibration. Replace fan blade assembly if any of
these conditions are found. Also inspect wiring har-
ness and connectors for damage.
(1) Disconnect the battery negative cables.
(2) Remove coolant recovery container (Refer to 7 -
COOLING/ENGINE/COOLANT RECOVERY CON-
TAINER - REMOVAL).
(3) Using a fastener removal tool, remove the two
push pin fasteners from the fan shroud lower half.
(4) Unseat the four fastening tabs and remove the
lower radiator shroud.
(5) Disconnect electrical connector.
(6) Remove the electronically controlled viscous fan
drive electrical wire from the upper radiator shroud.
(7) Using a fastener removal tool, remove the wir-
ing harness bracket from the upper radiator shroud.
CAUTION: Do not remove the fan pulley bolts. This
pulley is under spring tension.
(8) The electronically controlled viscous fan drive/
fan blade assembly is attached (threaded) to the fan
pulley shaft (Fig. 4). Remove the fan blade/fan drive
assembly from fan pulley by turning the mounting
nut counterclockwise (as viewed from front). Threads
on the viscous fan drive areRIGHT-HAND.A36
MM Fan Wrench can be used. Place a bar or screw-
driver between the fan pulley bolts to prevent pulley
from rotating.
(9) Remove the upper radiator shroud mounting
bolts.(10) Remove the fan shroud and the fan blade/vis-
cous drive as an assembly from vehicle.
CAUTION: The electronically controlled viscous fan
drive is vibration and impact sensitive, especially at
the electrical connectors. Do not drop the unit.
(11) Remove the six fan blade-to-viscous fan drive
mounting bolts.
(12) Inspect the fan for cracked, chipped or dam-
aged fan blades.
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.
Fig. 4 Fan Blade/Viscous Fan Drive - 5.9L Diesel
1 - ELECTRICAL CONNECTOR
2 - VISCOUS FAN DRIVE
3 - FAN BLADE
4 - BOLT (6)
5 - RADIATOR FAN PULLEY
DRENGINE 7 - 35
RADIATOR FAN - GAS ENGINES (Continued)

REMOVAL
(1) Disconnect the battery negative cable.
(2) Drain the coolant (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(3) Remove the power cord from the heater by
unplugging (Fig. 7).
(4) Loosen (but do not completely remove) the
screw at center of block heater (Fig. 7).
(5) Remove the block heater by carefully prying
from side-to-side. Note the direction of the heating
element coil (up or down). The element coil must be
installed correctly to prevent damage.
INSTALLATION
(1) Clean and inspect the block heater hole.
(2) Install the new O-ring seal(s) to heater.
(3) Insert the block heater into cylinder block and
position the element properly.
(4) With the heater fully seated, tighten center
screw to 2 N´m (17 in. lbs.).
(5) Fill the cooling system with the recommended
coolant. (Refer to 7 - COOLING - STANDARD PRO-
CEDURE).
(6) Start and warm the engine.
(7) Check the block heater for leaks.
ENGINE BLOCK HEATER - 5.9L
DIESEL
DESCRIPTION
WARNING: DO NOT OPERATE ENGINE UNLESS
BLOCK HEATER CORD HAS BEEN DISCONNECTED
FROM POWER SOURCE AND SECURED IN PLACE.
THE POWER CORD MUST BE SECURED IN ITS
RETAINING CLIPS AND ROUTED AWAY FROM
EXHAUST MANIFOLDS AND MOVING PARTS.
An optional engine block heater is available on all
models. The heater is equipped with a power cord.
The heater is mounted in a threaded hole of the
engine cylinder block with the heating element
immersed in engine coolant. The cord is attached to
an engine compartment component with tie-straps.
The 5.9L diesel engine has the block heater located
on the right side of the engine below the exhaust
manifold next to the oil cooler (Fig. 8).
Fig. 6 Engine Block Heater - 3.7L/4.7L
1 - ENGINE BLOCK HEATER
Fig. 7 Engine Block Heater
1 - FREEZE PLUG HOLE
2 - BLOCK HEATER
3 - SCREW
4 - POWER CORD (120V AC)
5 - HEATING COIL
6 - OIL FILTER
DRENGINE 7 - 37
ENGINE BLOCK HEATER (Continued)