warning DODGE RAM 2003 Service Owner's Manual

WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM COOLANT CAN OCCUR.
Drain sufficient coolant to allow thermostat
removal. (Refer to 7 - COOLING/ENGINE/ENGINE
COOLANT THERMOSTAT - REMOVAL). Remove
accessory drive belt (Refer to 7 - COOLING/ACCES-
SORY DRIVE/DRIVE BELTS - REMOVAL).
Add coolant to radiator to bring level to within 6.3
mm (1/4 in) of the top of the thermostat housing.CAUTION: Avoid overheating. Do not operate
engine for an excessive period of time. Open drain-
cock immediately after test to eliminate boil over.
Start engine and accelerate rapidly three times, to
approximately 3000 rpm while observing coolant. If
internal engine combustion gases are leaking into
cooling system, bubbles will appear in coolant. If bub-
bles do not appear, internal combustion gas leakage
is not present.
DIAGNOSIS AND TESTING - COOLING SYSTEM
DIESEL ENGINE
COOLING SYSTEM DIAGNOSISÐDIESEL ENGINE
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE READS
LOWNOTE:
Information on dash cluster is
displayed based on broadcast data
from ECM. DTC will be set for
engine sensor circuit concern.1. Vehicle is equipped with a heavy
duty cooling system.1. None. System operating normally.
2. Thermostat stuck open 2. Inspect and test thermostat.
3. Coolant level low. 3. Fill cooling system. (Refer to 7 -
COOLING - STANDARD
PROCEDURE)
4. Temperature gauge not
functioning correctly.4. Check cluster (Refer to 8 -
ELECTRICAL/INSTRUMENT
CLUSTER - DIAGNOSIS AND
TESTING)
DRCOOLING 7 - 7
COOLING (Continued)

COOLING SYSTEM DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE
READS LOW1. Has a Diagnostic Trouble
Code (DTC) been set indicating
a stuck open thermostat?1. (Refer to 25 - EMISSIONS CONTROL -
DESCRIPTION) for On-Board Diagnostics
and DTC information. Replace thermostat
if necessary.
2. Is the temperature sending
unit connected?2. Check the temperature sensor
connector. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - SCHEMATIC -
ELECTRICAL) Repair connector if
necessary.
3. Is the temperature gauge
operating OK?3. Check gauge operation. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER/
ENGINE TEMPERATURE GAUGE -
DESCRIPTION). Repair as necessary.
4. Coolant level low in cold
ambient temperatures
accompanied with poor heater
performance.4. Check coolant level in the coolant
reserve/overflow tank or degas bottle and
the radiator. Inspect system for leaks.
Repair leaks as necessary. Refer to the
Coolant section of the manual text for
WARNINGS and CAUTIONS associated
with removing the radiator cap.
5. Improper operation of internal
heater doors or heater controls.5. Inspect heater and repair as necessary.
(Refer to 24 - HEATING & AIR
CONDITIONING - DIAGNOSIS AND
TESTING) for procedures.
DRCOOLING 7 - 11
COOLING (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
TEMPERATURE GAUGE
READS HIGH OR THE
COOLANT WARNING LAMP
ILLUMINATES. COOLANT MAY
OR MAY NOT BE LOST OR
LEAKING FROM THE COOLING
SYSTEM1. Trailer is being towed, a steep
hill is being climbed, vehicle is
operated in slow moving traffic,
or engine is being idled with
very high ambient (outside)
temperatures and the air
conditioning is on. Higher
altitudes could aggravate these
conditions.1. This may be a temporary condition and
repair is not necessary. Turn off the air
conditioning and attempt to drive the
vehicle without any of the previous
conditions. Observe the temperature
gauge. The gauge should return to the
normal range. If the gauge does not return
to the normal range, determine the cause
for overheating and repair. Refer to
Possible Causes (2-18).
2. Is the temperature gauge
reading correctly?2. Check gauge. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER -
SCHEMATIC - ELECTRICAL). Repair as
necessary.
3. Is the temperature warning
illuminating unnecessarily?3. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - SCHEMATIC -
ELECTRICAL).
4. Coolant low in coolant
reserve/overflow tank and
radiator?4. Check for coolant leaks and repair as
necessary. (Refer to 7 - COOLING -
DIAGNOSIS AND TESTING).
5. Pressure cap not installed
tightly. If cap is loose, boiling
point of coolant will be lowered.
Also refer to the following Step
6.5. Tighten cap
6. Poor seals at the radiator
cap.6. (a) Check condition of cap and cap
seals. Refer to Radiator Cap. Replace cap
if necessary.
(b) Check condition of radiator filler neck.
If neck is bent or damaged, replace
radiator (5.9L) or degas bottle (3.7L, 4.7L).
7. Coolant level low in radiator
but not in coolant reserve/
overflow tank. This means the
radiator is not drawing coolant
from the coolant reserve/
overflow tank as the engine
cools (5.9L).7. (a) Check condition of radiator cap and
cap seals. Refer to Radiator Cap in this
Group. Replace cap if necessary.
(b) Check condition of radiator filler neck.
If neck is bent or damaged, replace
radiator.
(c) Check condition of the hose from the
radiator to the coolant tank. It should fit
tight at both ends without any kinks or
tears. Replace hose if necessary.
(d) Check coolant reserve/overflow tank
and tanks hoses for blockage. Repair as
necessary.
8. Incorrect coolant
concentration8. Check coolant. (Refer to LUBRICATION
& MAINTENANCE/FLUID TYPES -
DESCRIPTION).
9. Coolant not flowing through
system9. Check for coolant flow at radiator filler
neck with some coolant removed, engine
warm and thermostat open. Coolant
should be observed flowing through
radiator. If flow is not observed, determine
area of obstruction and repair as
necessary.
7 - 12 COOLINGDR
COOLING (Continued)

STANDARD PROCEDURE
STANDARD PROCEDURE - COOLANT LEVEL
CHECK
NOTE: Do not remove radiator cap for routine cool-
ant level inspections. The coolant level can be
checked at coolant recovery bottle or the coolant
degas bottle.
WARNING: DO NOT REMOVE OR LOOSEN THE
RADIATOR CAP WITH THE COOLING SYSTEM HOT
AND UNDER PRESSURE. SERIOUS BURNS FROM
COOLANT OR HIGH PRESSURE STEAM CAN
OCCUR.
The 5.9L, 5.9L Diesel, and 8.0L engine coolant
reserve / overflow system provides a quick method for
determining the coolant level without removing the
radiator pressure cap. With the engine at normal
operating temperature and idling, observe the level
of the coolant on the external level indicator on the
side of the coolant reserve / overflow bottle. The cool-
ant level should be between the MIN and MAX
marks. If the coolant is below the MIN mark, add a
50/50 mixture of antifreeze and water to the bottle
until the level reaches the MIN mark.Do Not Over-
fill the bottle by adding fluid above the MAX
line.This may cause coolant to spill onto the ground
during subsequent vehicle operation.
The 3.7L/4.7L/5.9L engine coolant degas system
provides a quick method for determining the coolant
level with out removing the radiator pressure cap.
With a cold engine, observe the level of coolant in the
degas bottle. The level should be in the COLD FILL
RANGE.DO NOT OVERFILLthe bottle by adding
fluid above the COLD FILL RANGE. This may cause
coolant to spill onto the ground during subsequent
vehicle operation.
STANDARD PROCEDURE - COOLING SYSTEM
CLEANING/REVERSE FLUSHING
CLEANING
Drain the cooling system and refill with water. Run
the engine with the radiator cap installed until the
upper radiator hose is hot. Stop the engine and drain
the water from system. If the water is dirty, fill the
system with water, run the engine and drain the sys-
tem. Repeat this procedure until the water drains
clean.
REVERSE FLUSHING
Reverse flushing of the cooling system is the forc-
ing of water through the cooling system. This is doneusing air pressure in the opposite direction of normal
coolant flow. It is usually only necessary with very
dirty systems with evidence of partial plugging.
REVERSE FLUSHING RADIATOR
Disconnect the radiator hoses from the radiator
inlet and outlet. Attach a section of the radiator hose
to the radiator bottom outlet fitting and insert the
flushing gun. Connect a water supply hose and air
supply hose to the flushing gun.
CAUTION: Internal radiator pressure must not
exceed 138 kPa (20 psi) as damage to radiator may
result.
Allow the radiator to fill with water. When the
radiator is filled, apply air in short blasts. Allow the
radiator to refill between blasts. Continue this
reverse flushing until clean water flows out through
the rear of the radiator cooling tube passages.
REVERSE FLUSHING ENGINE
Drain the cooling system. Remove the thermostat
housing and thermostat. Install the thermostat hous-
ing. Disconnect the radiator upper hose from the
radiator and attach the flushing gun to the hose. Dis-
connect the radiator lower hose from the water pump
and attach a lead-away hose to the water pump inlet
fitting.
CAUTION: On vehicles equipped with a heater water
control valve, be sure the heater control valve is
closed (heat off). This will prevent coolant flow with
scale and other deposits from entering the heater
core.
Connect the water supply hose and air supply hose
to flushing gun. Allow the engine to fill with water.
When the engine is filled, apply air in short blasts,
allowing the system to fill between air blasts. Con-
tinue until clean water flows through the lead away
hose.
Remove the lead away hose, flushing gun, water
supply hose and air supply hose. Remove the thermo-
stat housing and install the thermostat. Install the
thermostat housing with a replacement gasket. Refer
to Thermostat Replacement. Connect the radiator
hoses. Refill the cooling system with the correct anti-
freeze/water mixture. Refer to Refilling the Cooling
System.
CHEMICAL CLEANING
In some instances, use a radiator cleaner (Mopart
Radiator Kleen or equivalent) before flushing. This
will soften scale and other deposits and aid flushing
operation.
DRCOOLING 7 - 17
COOLING (Continued)

CAUTION: Follow manufacturers instructions when
using these products.
STANDARD PROCEDUREÐDRAINING COOLING
SYSTEM 3.7L/4.7L/5.7L ENGINE
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS (Fig. 6) OR LOOSEN THE
RADIATOR DRAINCOCK WITH SYSTEM HOT AND
UNDER PRESSURE. SERIOUS BURNS FROM
COOLANT CAN OCCUR.
(1) With the engine cold, raise the vehicle on a
hoist and locate the radiator draincock.
NOTE: Radiator draincock is located on the left/
lower side of radiator facing to rear of vehicle.
(2) Attach one end of a hose to the draincock. Put
the other end into a clean container. Remove the
radiator cap, open the draincock and drain the cool-
ing system.
(3) If draining the entire engine is required,
remove the cylinder block drain plugs.
STANDARD PROCEDURE - REFILLING
COOLING SYSTEM 3.7L/4.7L/5.7L ENGINE
DO NOT WASTE REUSABLE COOLANT.Ifthe
solution is clean, drain the coolant into a clean con-
tainer for reuse.(1) Install the cylinder block drain plugs (if
removed). Coat the threads with MopartThread
Sealant with Teflon.
(2) Close the radiator draincock.
CAUTION: Failure to purge air from the cooling sys-
tem can result in an overheating condition and
severe engine damage.
(3) Fill system using a 50/50 mixture antifreeze
and low mineral content water. Stop filling when the
level in the degas bottle has reached the top of the
COLD FILL RANGE.
(4) Start and operate the engine until the thermo-
stat opens (upper radiator hose is warm to the
touch).
(5) If necessary, add a 50/50 mixture of anti-freeze
and water to the degass bottle to maintain the proper
coolant level in the degas bottle.
(6) Install the radiator cap.
STANDARD PROCEDUREÐDRAINING COOLING
SYSTEM 5.9L/8.0L ENGINE
WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM COOLANT CAN OCCUR.
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
(1) Attach one end of a hose to the draincock. Put
the other end into a clean container.
(2)DO NOT REMOVE THE RADIATOR CAP
when draining the coolant from the reservoir/over-
flow tank. Open radiator draincock and when the
tank is empty, remove the radiator cap and continue
draining the cooling system.
(3) If draining the entire engine, remove the cylin-
der block drain plugs. Refer to (Fig. 7).
STANDARD PROCEDUREÐREFILLING
COOLING SYSTEM 5.9L/8.0L ENGINE
WARNING: DO NOT REMOVE CYLINDER BLOCK
DRAIN PLUGS OR LOOSEN RADIATOR DRAIN-
COCK WITH SYSTEM HOT AND UNDER PRESSURE.
SERIOUS BURNS FROM COOLANT CAN OCCUR.
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean container for reuse.
Clean cooling system prior to refilling. (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(1) Install cylinder block drain plugs. Coat the
threads with MopartThread Sealant with Teflon.
(2) Close radiator petcock.
Fig. 6 Drain Plug - 3.7L/4.7L Engine
1 - CYLINDER BLOCK DRAIN PLUG
2 - EXHAUST MANIFOLD AND HEAT SHIELD
7 - 18 COOLINGDR
COOLING (Continued)

(3) Fill cooling system with a 50/50 mixture of
water and antifreeze.
(4) Fill coolant reserve/overflow tank to MAX mark
on bottle.
(5) Start and operate engine until thermostat
opens (upper radiator hose warm to touch).
(6) If necessary, add a 50/50 water and antifreeze
mixture to the coolant reserve/overflow tank. This is
done to maintain coolant level between the MAX and
MIN marks. The level in the reserve/overflow tank
may drop below the MIN mark after three or four
warm-up and cool-down cycles.
STANDARD PROCEDUREÐDRAINING COOLING
SYSTEM 5.9L DIESEL ENGINE
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAIN PLUG WITH SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR.
DO NOT WASTE reusable coolant. If the solution
is clean, drain the coolant into a clean container for
reuse.
(1) Start the engine and place the heater control
temperature selector in the Full-On position.
(2) Turn the ignition off.
(3) Do not remove radiator cap when draining cool-
ant from reserve/overflow tank. Open radiator drain
plug and when tank is empty, remove radiator cap. If
the coolant reserve/overflow tank does not drain,
(Refer to 7 - COOLING - DIAGNOSIS AND TEST-
ING). The coolant need not be removed from tank
unless the system is being refilled with fresh mix-
ture.
(4) Remove radiator pressure cap.
STANDARD PROCEDUREÐREFILLING
COOLING SYSTEM 5.9L DIESEL ENGINE
Clean cooling system prior to refilling (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(1) Close radiator drain plug.
CAUTION: Due to the use of the one-way check
valve, the engine must not be operating when refill-
ing the cooling system.
NOTE: The diesel engine is equipped with two one-
way check valves (jiggle pins). The check valves
are used as a servicing feature and will vent air
when the system is being filled. Water pressure (or
flow) will hold the valves closed.
(2) Fill the cooling system with a 50/50 mixture of
water and antifreeze.
(3) Fill coolant reserve/overflow tank to the FULL
mark.
(4) Start and operate engine until thermostat
opens. Upper radiator hose should be warm to touch.
(5) If necessary, add 50/50 water and antifreeze
mixture to the coolant reserve/overflow tank to main-
tain coolant level. This level should be between the
ADD and FULL marks. The level in the reserve/over-
flow tank may drop below the ADD mark after three
or four warm-up and cool-down cycles.
STANDARD PROCEDURE - ADDING
ADDITIONAL COOLANT
The use of aluminum cylinder blocks, cylinder
heads and water pumps requires special corrosion
protection. Only MopartAntifreeze/Coolant, 5
Year/100,000 Mile Formula (glycol base coolant with
corrosion inhibitors called HOAT, for Hybrid Organic
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). If it loses color or becomes con-
taminated, drain, flush, and replace with fresh prop-
erly mixed coolant solution.
CAUTION: Do not use coolant additives that are
claimed to improve engine cooling.
For 5.9L engines, do not remove the radiator cap to
add coolant to the system. When adding coolant to
maintain the correct level, do so only at the reserve/
overflow bottle. Remove the radiator cap only for
testing or when refilling the system after service.
Removing the cap unnecessarily can cause loss of
coolant and allow air to enter the system, which pro-
duces corrosion.
Fig. 7 Cylinder Block Drain Plug - 5.9L Engines
1 - BLOCK DRAIN PLUG
DRCOOLING 7 - 19
COOLING (Continued)

WARNING: DO NOT REMOVE OR LOOSEN THE
RADIATOR CAP WITH THE COOLING SYSTEM HOT
AND UNDER PRESSURE. SERIOUS BURNS FROM
THE COOLANT OR HIGH PRESSURE STEAM CAN
OCCUR.
For 3.7L / 4.7L/5.9L engines, remove the radiator
cap from the coolant degas bottle to add coolant.
SPECIFICATIONS
TORQUE
DESCRIPTION N´m Ft. In.
Lbs. Lbs.
Automatic Belt Tensioner to
BlockÐBolts 41 30 Ð
Automatic Belt Tensioner
PulleyÐBolt 61 45 Ð
Block HeaterÐBolt 2 Ð 17
Generator/Compressor
Mounting BracketÐBolts
# 1 and 2 54 40 Ð
# 3 40 30 Ð
Fan Shroud to Radiator
MountingÐBolts6Ð55
Radiator to Support - Bolts 8.5 Ð 75
Fan Blade to Viscous Fan
DriveÐBolts24 18 Ð
Idler PulleyÐBolt 54 40 Ð
Thermostat HousingÐBolts
- All Except 5.9L13 Ð 112
Thermostat HousingÐBolts
- 5.9L23 16 Ð
Power Steering Oil Cooler
Ð Bolts6Ð55
Transmission Auxiliary Oil
CoolerÐBolts 6 Ð 55
Transmission Oil Cooler
Tube Nuts31.5 24 Ð
Coolant Bottle Ð Bolts 8.5 Ð 75
Transmission Oil Cooler to
Transmission - 5.9L/46RE -
Tube Nuts 31.5 24 Ð
Transmission Oil Cooler to
Transmission - 3.7L/4.7L/
45RFE - Tube Nuts20 18 Ð
Water PumpÐBolts 24 18 Ð
Water Pump Ð Bolts - 4.7L 58 43 Ð
SPECIFICATIONS -
SPECIFICATIONS
DESCRIPTION SPECIFICATION
3.7/4.7L Engine 15.4L (16.2 qts.)- to the
middle of the cold fill
range
5.7L Engine 15.4L (16.2 qts.)- to the
middle of the cold fill
range
5.9L Engine 15.5L (16.3 qts.)- to the
MIN mark after 3 warm
up, cool down cycles
8.0L Engine 24L (25.3 qts.)
5.9L Diesel Engine 28L (29.5 qts.)
SPECIAL TOOLS
COOLING
Pliers Constant Pressure Hose Clamp - 6094
3/8º Quick Connect Release Tool - 6935
SPANNER WRENCHÐ6958
7 - 20 COOLINGDR
COOLING (Continued)

NOTE: A used belt should be replaced if tensioner
indexing arrow has moved to the minimum tension
indicator. Tensioner travel stops at this point.
(1) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(2) Remove tensioner assembly from mounting
bracket (Fig. 2).
WARNING: BECAUSE OF HIGH SPRING PRES-
SURE, DO NOT ATTEMPT TO DISASSEMBLE AUTO-
MATIC TENSIONER. UNIT IS SERVICED AS AN
ASSEMBLY EXCEPT FOR PULLEY ON TENSIONER.
(3) Remove pulley bolt. Remove pulley from ten-
sioner.
INSTALLATION
(1) Install pulley and pulley bolt to tensioner.
Tighten bolt to 61 N´m (45 ft. lbs.) torque.
(2) An indexing slot is located on back of tensioner.
Align this slot to the head of the bolt on the front
cover. Install the mounting bolt. Tighten bolt to 41
N´m (30 ft. lbs.).
(3) Install accessory drive belt (Refer to 7 - COOL-
ING/ACCESSORY DRIVE/DRIVE BELTS - INSTAL-
LATION).
(4) Check belt indexing marks (Fig. 1).
BELT TENSIONERS - 5.9L
DESCRIPTION
Correct drive belt tension is required to ensure
optimum performance of the belt driven engine acces-
sories. If specified tension is not maintained, belt
slippage may cause; engine overheating, lack of
power steering assist, loss of air conditioning capac-
ity, reduced generator output rate, and greatly
reduced belt life.
It is not necessary to adjust belt tension on the
3.9L or 5.9L engines. These engines are equipped
with an automatic belt tensioner (Fig. 3). The ten-
sioner maintains correct belt tension at all times.
Due to use of this belt tensioner, do not attempt to
use a belt tension gauge on 3.9L or 5.9L engines.
OPERATION
The automatic belt tensioner maintains belt ten-
sion by using internal spring pressure, a pivoting
arm and pulley to press against the drive belt.
REMOVAL
WARNING: BECAUSE OF HIGH SPRING PRES-
SURE, DO NOT ATTEMPT TO DISASSEMBLE AUTO-
MATIC TENSIONER. UNIT IS SERVICED AS AN
ASSEMBLY (EXCEPT FOR PULLEY).
(1) Remove accessory drive belt. (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(2) Disconnect wiring and secondary cable from
ignition coil.
(3) Remove ignition coil from coil mounting
bracket (two bolts). Do not remove coil mounting
bracket from cylinder head.
(4) Remove tensioner assembly from mounting
bracket (one nut) (Fig. 4).
Fig. 2 AUTOMATIC BELT TENSIONER - 3.7L/4.7L
ENGINE
1 - TIMING CHAIN COVER
2 - BOLT TORQUE TO 41 N´m (30 FT LBS)
3 - AUTOMATIC BELT TENSIONER
Fig. 3 Automatic Belt Tensioner - 5.9L Engines
1 - AUTOMATIC TENSIONER
2 - COIL AND BRACKET
3 - SCREW AND WASHER
DRACCESSORY DRIVE 7 - 23
BELT TENSIONERS - 3.7L / 4.7L (Continued)

(5) Remove pulley bolt. Remove pulley from ten-
sioner.
INSTALLATION
(1) Install pulley and pulley bolt to tensioner.
Tighten bolt to 61 N´m (45 ft. lbs.) torque.
(2) Install tensioner assembly to mounting
bracket. An indexing tab is located on back of ten-
sioner. Align this tab to slot in mounting bracket.
Tighten nut to 67 N´m (50 ft. lbs.) torque.
(3) Connect all wiring to ignition coil.
CAUTION: To prevent damage to coil case, coil
mounting bolts must be torqued.
(4) Install coil to coil bracket. If nuts and bolts are
used to secure coil to coil bracket, tighten to 11 N´m
(100 in. lbs.) torque. If coil mounting bracket has
been tapped for coil mounting bolts, tighten bolts to 5
N´m (50 in. lbs.) torque.
(5) Install drive belt. (Refer to 7 - COOLING/AC-
CESSORY DRIVE/DRIVE BELTS - INSTALLA-
TION).
(6) Check belt indexing marks (Fig. 4).
BELT TENSIONERS - 5.9L
DIESEL
DESCRIPTION
Drive belts on all engines are equipped with a
spring loaded automatic belt tensioner (Fig. 5). 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.
Fig. 4 Tensioner Indexing Marks And Mounting Nut
1 - TENSIONER ASSEMBLY
2 - TENSIONER MOUNTING NUT
3 - INDEXING ARROW
4 - INDEXING MARK
Fig. 5 Belt
1 - GENERATOR
2 - WATER PUMP
3 - IDLER
4 - POWER STEERING PUMP
5 - AUTOMATIC TENSIONER
6 - A/C COMPRESSOR
7 - 24 ACCESSORY DRIVEDR
BELT TENSIONERS - 5.9L (Continued)

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. 6) and
remove tensioner.
INSTALLATION
(1) Install tensioner assembly to mounting
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 BELTS - 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. 7), 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. 7). 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.
Fig. 6 AUTOMATIC BELT TENSIONER DIESEL
ENGINE-TYPICAL
1 - GENERATOR
2 - WATER PUMP
3 - IDLER
4 - POWER STEERING PUMP
5 - AUTOMATIC TENSIONER
6 - A/C COMPRESSOR
Fig. 7 Belt Wear Patterns
1 - NORMAL CRACKS BELT OK
2 - NOT NORMAL CRACKS REPLACE BELT
DRACCESSORY DRIVE 7 - 25
BELT TENSIONERS - 5.9L DIESEL (Continued)