Engine system DODGE RAM 2003 Service Workshop Manual

DIAGNOSIS AND TESTINGÐRADIATOR
COOLANT FLOW
Use the following procedure to determine if coolant
is flowing through the cooling system.
(1) Idle engine until operating temperature is
reached. If the upper radiator hose is warm to the
touch, the thermostat is opening and coolant is flow-
ing to the radiator.
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. USING A RAG TO
COVER THE RADIATOR PRESSURE CAP, OPEN
RADIATOR CAP SLOWLY TO THE FIRST STOP. THIS
WILL ALLOW ANY BUILT-UP PRESSURE TO VENT
TO THE RESERVE/OVERFLOW TANK. AFTER PRES-
SURE BUILD-UP HAS BEEN RELEASED, REMOVE
CAP FROM FILLER NECK.
(2) Drain a small amount of coolant from the radi-
ator until the ends of the radiator tubes are visible
through the filler neck. Idle the engine at normal
operating temperature. If coolant is flowing past the
exposed tubes, the coolant is circulating.
REMOVAL
(1) Disconnect battery negative cables.WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM THE COOL-
ANT CAN OCCUR.
(2) Drain the cooling system (Refer to 7 - COOL-
ING - STANDARD PROCEDURE).
WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP. ALWAYS WEAR SAFETY GLASSES WHEN
SERVICING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps. If replacement
is necessary, use only an original equipment clamp
with a matching number or letter and the correct
width.
(3) Remove the hose clamps and hoses from radia-
tor.
(4) Remove the coolant reserve/overflow tank hose
from the radiator filler neck.
(5) Remove the coolant reserve/overflow tank
(5.9L) or the coolant degas container(3.7L/4.7L) from
the fan shroud (pull straight up). The tank slips into
slots on the fan shroud.
(6) Unclip the power steering hoses from the fan
shroud.
(7) Disconnect the electrical connectors at the
windshield washer reservoir tank and remove the
tank.
(8) Remove the fan shroud mounting bolts and pull
up and out of the radiator tank clips (Fig. 33). Posi-
tion shroud rearward over the fan blades towards
engine.
(9) Disconnect the transmission cooler lines from
the transmission cooler, then plug the transmission
lines and cooler to prevent leakage.
(10) Disconnect the power steering lines from the
power steering cooler, then plug the power steering
lines and cooler to prevent leakage.
(11) Remove the two radiator upper mounting
bolts (Fig. 34).
(12) Lift the radiator straight up and out of the
engine compartment. Take care not to damage cool-
ing fins or tubes on the radiator and oil coolers when
removing.
Fig. 32 Radiator Ð Typical
1 - SCREW
2 - SCREW
3 - LOWER MOUNT
4 - RADIATOR
5 - DRAINCOCK
6 -LOWER MOUNT
DRENGINE 7 - 57
RADIATOR (Continued)

(12) Install coolant reserve/overflow container or
degas container to fan shroud and tighten the bolts
to 8.5 N´m (75 in. lbs.).
(13) Connect upper radiator hose and install
clamp.
(14) Install battery negative cable.
(15) Fill cooling system with coolant (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(16) Operate the engine until it reaches normal
operating temperature. Check cooling system fluid
levels.
RADIATOR - 5.9L DIESEL
DESCRIPTION
The radiator is a aluminum cross-flow design with
horizontal tubes through the radiator core and verti-
cal plastic side tanks (Fig. 35).
This radiator does not contain an internal trans-
mission oil cooler
OPERATION
The radiator supplies sufficient heat transfer using
the cooling fins interlaced between the horizontal
tubes in the radiator core to cool the engine.
DIAGNOSIS AND TESTINGÐRADIATOR
COOLANT FLOW
Use the following procedure to determine if coolant
is flowing through the cooling system.
(1) Idle engine until operating temperature is
reached. If the upper radiator hose is warm to the
touch, the thermostat is opening and coolant is flow-
ing to the radiator.
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. USING A RAG TO
COVER THE RADIATOR PRESSURE CAP, OPEN
RADIATOR CAP SLOWLY TO THE FIRST STOP. THIS
WILL ALLOW ANY BUILT-UP PRESSURE TO VENT
TO THE RESERVE/OVERFLOW TANK. AFTER PRES-
SURE BUILD-UP HAS BEEN RELEASED, REMOVE
CAP FROM FILLER NECK.
(2) Drain a small amount of coolant from the radi-
ator until the ends of the radiator tubes are visible
through the filler neck. Idle the engine at normal
operating temperature. If coolant is flowing past the
exposed tubes, the coolant is circulating.
REMOVAL
(1) Disconnect both battery negative cables.
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK DRAIN PLUGS OR LOOSEN THE RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND UNDER
PRESSURE. SERIOUS BURNS FROM COOLANT
CAN OCCUR.
(2) Drain the cooling system (Refer to 7 - COOL-
ING - STANDARD PROCEDURE).
WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.
WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER
6094). SNAP-ON CLAMP TOOL (NUMBER HPC-20)
MAY BE USED FOR LARGER CLAMPS. ALWAYS
WEAR SAFETY GLASSES WHEN SERVICING CON-
STANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps. If replacement
is necessary, use only an original equipment clamp
with a matching number or letter.
(3) Remove air box and turbocharger inlet tube.
(4) Remove coolant tank hose, washer bottle hose
and the positive battery cable from the fastening
clips located on top of the radiator.
(5) Remove hose clamps and hoses from radiator.
Fig. 35 Radiator Ð Typical
1 - SCREW
2 - SCREW
3 - LOWER MOUNT
4 - RADIATOR
5 - DRAINCOCK
6 -LOWER MOUNT
DRENGINE 7 - 59
RADIATOR (Continued)

(6) Remove the power steering cooler mounting
bolts and position the power steering cooler out of
the way.
(7) Disconnect the transmission cooler lines at the
transmission. The transmission cooler will remain on
the radiator and can be removed as an assembly.
(8) Remove the lower shroud assembly and the
electronic viscous fan wiring from the upper shroud
assembly.
(9) Remove the two radiator upper mounting bolts
(Fig. 36).
(10) Lift radiator straight up and out of engine
compartment. The bottom of the radiator is equipped
with two alignment dowels that fit into holes in the
lower radiator support panel. Rubber biscuits (insu-
lators) are installed to these dowels. Take care not to
damage cooling fins or tubes on the radiator and air
conditioning condenser when removing.
CLEANING
Clean radiator fins are necessary for good heat
transfer. The radiator and oil cooler fins should be
cleaned when an accumulation of debris has
occurred. With the engine cold, apply cold water and
compressed air to the back (engine side) of the radi-
ator to flush the radiator and/or oil coolers of debris.
INSPECTION
Inspect the radiator side tanks for cracks, broken
or missing fittings also inspect the joint where the
tanks seam up to the radiator core for signs of leak-
age and/or deteriorating seals.
Inspect radiator core for corroded, bent or missing
cooling fins. Inspect the core for bent or damaged
cooling tubes.
INSTALLATION
(1) Install rubber insulators to alignment dowels
at lower part of radiator.
(2) Lower the radiator into position while guiding
the two alignment dowels into lower radiator sup-
port. Different alignment holes are provided in the
lower radiator support for each engine application.
(3) Install two upper radiator mounting bolts.
Tighten bolts to 11 N´m (95 in. lbs.) torque.
(4) Connect both radiator hoses and install hose
clamps.
(5) Connect transmission cooler lines to radiator
tank. Inspect quick connect fittings for debris and
install until an audible ªclickº is heard. Pull apart to
verify connection.
(6) Position power steering cooler on the radiator
and tighten nuts to 8.5M´N (75 in. lbs.)
(7) Attach electronic viscous fan wiring to upper
shroud ands install lower shroud.
(8) Position coolant recover tank hose, washer bot-
tle hose and the positive battery cable into the clips
located on the top of the radiator.
(9) Install air box and turbocharger inlet hose.
Tighten clamps to 4 N´M (35 in. lbs.).
(10) Position heater controls tofull heatposition.
(11) Fill cooling system with coolant (Refer to 7 -
COOLING - STANDARD PROCEDURE).
(12) Operate engine until it reaches normal tem-
perature. Check cooling system and automatic trans-
mission (if equipped) fluid levels.
RADIATOR PRESSURE CAP
DESCRIPTION
All cooling systems are equipped with a pressure
cap (Fig. 37). For 5.9L engines, the pressure cap is
located on top of the radiator outlet tank. For the
3.7L/4.7L engines, the pressure cap is located on top
of the coolant degas container. The cap releases pres-
sure at some point within a range of 97-to-124 kPa
(14-to-18 psi). The pressure relief point (in pounds) is
engraved on top of the cap
The cooling system will operate at pressures
slightly above atmospheric pressure. This results in a
higher coolant boiling point allowing increased radi-
ator cooling capacity. The cap contains a spring-
Fig. 36 Fan Shroud MountingÐ5.9L Diesel Engine
1 - RADIATOR SUPPORT
2 - UPPER FAN SHROUD
3 - BOLTS (2)
4 - LOWER FAN SHROUD
5 - RADIATOR
7 - 60 ENGINEDR
RADIATOR - 5.9L DIESEL (Continued)

loaded pressure relief valve. This valve opens when
system pressure reaches the release range of 97-to-
124 kPa (14-to-18 psi).
A rubber gasket seals the radiator filler neck. This
is done to maintain vacuum during coolant cool-down
and to prevent leakage when system is under pres-
sure.
OPERATION
A vent valve in the center of the cap will remain
shut as long as the cooling system is pressurized. As
the coolant cools, it contracts and creates a vacuum
in the cooling system. This causes the vacuum valve
to open and coolant in the reserve/overflow container
to be drawn through the recovery hose connecting
the filler neck and reserve/overflow container. If the
vacuum valve is stuck shut, or the recovery hose is
kinked, radiator hoses will collapse on cool down.
For the 3.7L/4.7L engine, the vacuum valve will
open and relieve the vacuum pressure in the cooling
system.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTINGÐRADIATOR
CAP-TO-FILLER NECK SEAL
The pressure cap upper gasket (seal) pressure
relief can be tested by removing overflow hose from
the radiator filler neck tube. Attach the hose of the
pressure tester tool 7700 (or equivalent) to the tube.
It will be necessary to disconnect hose from its
adapter for the filler neck. Pump air into radiator.
The pressure cap upper gasket should relieve at 69
to 124kPa (10 to 18 psi) and hold pressure at a min-
imum of 55 kPa (8 psi).
WARNING: THE WARNING WORDS ÐDO NOT
OPEN HOTÐ ON RADIATOR PRESSURE CAP, ARE
A SAFETY PRECAUTION. WHEN HOT, PRESSURE
BUILDS UP IN COOLING SYSTEM. TO PREVENT
SCALDING OR INJURY, RADIATOR CAP SHOULD
NOT BE REMOVED WHILE SYSTEM IS HOT AND/OR
UNDER PRESSURE.
Do not remove the radiator cap at any timeexcept
for the following purposes:
(1) Check and adjust antifreeze freeze point.
(2) Refill the system with new antifreeze.
(3) Conducting service procedures.
(4) Checking for vacuum leaks.
WARNING: IF VEHICLE HAS BEEN RUN RECENTLY,
WAIT AT LEAST 15 MINUTES BEFORE REMOVING
RADIATOR CAP. WITH A RAG, SQUEEZE RADIATOR
UPPER HOSE TO CHECK IF SYSTEM IS UNDER
PRESSURE. PLACE A RAG OVER CAP AND WITH-
OUT PUSHING CAP DOWN, ROTATE IT COUNTER-
CLOCKWISE TO FIRST STOP. ALLOW FLUID TO
ESCAPE THROUGH THE COOLANT RESERVE/
OVERFLOW HOSE INTO RESERVE/OVERFLOW
TANK. SQUEEZE RADIATOR UPPER HOSE TO
DETERMINE WHEN PRESSURE HAS BEEN
RELEASED. WHEN COOLANT AND STEAM STOP
BEING PUSHED INTO TANK AND SYSTEM PRES-
SURE DROPS, REMOVE RADIATOR CAP COM-
PLETELY.
DIAGNOSIS AND TESTING - RADIATOR CAP
Remove the cap from the radiator. Be sure that the
sealing surfaces are clean. Moisten the rubber gasket
with water and install the cap on the pressure tester
7700 or an equivalent (Fig. 38).
Operate the tester pump to bring the pressure to
104 kPa (15 psi) on the gauge. If the pressure cap
fails to hold pressure of at least 97 kPa (14 psi)
replace the cap. Refer to the followingCAUTION.
Fig. 37 Radiator Pressure Cap - Typical
1 - FILLER NECK SEAL
2 - VACUUM VENT VALVE
3 - PRESSURE RATING
4 - PRESSURE VALVE
DRENGINE 7 - 61
RADIATOR PRESSURE CAP (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. 39) 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 - 5.9L
DESCRIPTION
The water pump is located on the engine front
cover, and has an integral pulley attached (Fig. 40).
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
A centrifugal water pump circulates coolant
through the water jackets, passages, intake manifold,
radiator core, cooling system hoses and heater core,
this coolant absorbs the heat generated when the
engine is running. The pump is driven by the engine
crankshaft via a 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.
Fig. 38 Pressure Testing Radiator Cap - Typical
1 - PRESSURE CAP
2 - TYPICAL COOLING SYSTEM PRESSURE TESTER
Fig. 39 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
7 - 62 ENGINEDR
RADIATOR PRESSURE CAP (Continued)

REMOVAL
The water pump on all models can be removed
without discharging the air conditioning system (if
equipped).
The water pump on all gas powered engines is
bolted directly to the engine timing chain case/cover.
On the 5.9L gas powered engine, a gasket is used
as a seal between the water pump and timing chain
case/cover.
If water pump is replaced because of bearing/shaft
damage or leaking shaft seal, the mechanical cooling
fan assembly should also be inspected. Inspect for
fatigue cracks, loose blades or loose rivets that could
have resulted from excessive vibration. Replace fan if
any of these conditions are found. Also check condi-
tion of the thermal viscous fan drive (Refer to 7 -
COOLING/ENGINE/FAN DRIVE VISCOUS
CLUTCH - DIAGNOSIS AND TESTING).
(1) Disconnect the negative cable.
(2) Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
Do not waste reusable coolant. If solution is clean,
drain coolant into a clean container for reuse.
(3) Remove the radiator fan (Refer to 7 - COOL-
ING/ENGINE/RADIATOR FAN - REMOVAL)
(4) Remove accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL) (Fig. 41).
(5) Remove the lower radiator hose and heater
hose from the water pump.
(6) Loosen the heater hose coolant return tube
mounting bolt (Fig. 42) and remove the tube from the
water pump. Discard the old tube O-ring.
(7) Remove the water pump mounting bolts (Fig.
43).(8) Loosen the clamp at the water pump end of
bypass hose (Fig. 42). Slip the bypass hose from the
Fig. 40 Water Pump Location Ð Typical
1 - WATER PUMP BYPASS HOSE
2 - FAN BLADE ASSEMBLY
3 - VISCOUS FAN DRIVE
4 - WATER PUMP AND PULLEY
Fig. 41 Belt Tensioner 5.9L V-8 Engine
1 - IDLER PULLEY
2 - TENSIONER
3 - FAN BLADE
Fig. 42 Coolant Return Tube 5.9L
1 - COOLANT RETURN TUBE
2 - WATER PUMP
3 - TUBE MOUNTING BOLT
4 - O-RING
DRENGINE 7 - 63
WATER PUMP - 5.9L (Continued)

water pump while removing pump from vehicle. Do
not remove the clamp from the bypass hose.
(9) Discard the old gasket.
CAUTION: Do not pry the water pump at timing
chain case/cover. The machined surfaces may be
damaged resulting in leaks.
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) Clean the gasket mating surfaces.
(2) Using a new gasket, install the water pump to
the engine as follows: Guide the water pump tube
into the bypass hose as the pump is being installed.
Install the water pump bolts (Fig. 43). Tighten the
water pump mounting bolts to 40 N´m (30 ft. lbs.)
torque.
(3) Position the bypass hose clamp to the bypass
hose.
(4) Spin the water pump to be sure that the pump
impeller does not rub against the timing chain case/
cover.
(5) Install a new o-ring to the heater hose coolant
return tube (Fig. 42). Coat the new o-ring with anti-
freeze before installation.(6) Install the coolant return tube and its mount-
ing bolt to the engine (Fig. 42). Be sure the slot in
the tube bracket is bottomed to mounting bolt. This
will properly position return tube.
(7) Connect the radiator lower hose to the water
pump.
(8) Connect the heater hose and hose clamp to the
coolant return tube.
(9) Install drive belt (Refer to 7 - COOLING/AC-
CESSORY DRIVE/DRIVE BELTS - INSTALLATION)
(Fig. 41).
(10) Install the fan (Refer to 7 - COOLING/EN-
GINE/RADIATOR FAN - INSTALLATION)
(11) Fill cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(12) Connect negative battery cable.
(13) Start and warm the engine. Check for leaks.
WATER PUMP - 3.7L/4.7L
DESCRIPTION
DESCRIPTIONÐWATER 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.
44).
DESCRIPTIONÐWATER 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
engine warm-up preventing the coolant from flowing
through the radiator. The thermostat uses a stub
shaft located at the rear of the thermostat (Fig. 45)
to control flow through the bypass gallery.
OPERATION
OPERATIONÐWATER PUMP
A centrifugal water pump circulates coolant
through the water jackets, passages, intake manifold,
Fig. 43 Water Pump Bolts - 5.9L V-8 Gas Engine -
Typical
1 - WATER PUMP MOUNTING BOLTS
7 - 64 ENGINEDR
WATER PUMP - 5.9L (Continued)

radiator core, cooling system hoses and heater core,
this coolant absorbs the heat generated when the
engine is running. The pump is driven by the engine
crankshaft via a drive belt.
OPERATIONÐWATER PUMP BYPASS
When the thermostat is in the closed position the
bypass gallery is not obstructed allowing 100% flow.
When the thermostat is in the open position the stub
shaft enters the bypass gallery obstructing bypass
coolant flow by 50%. This design allows the coolant
to reach operating temperature quickly when cold,
while adding extra cooling during normal tempera-
ture operation.
REMOVAL
The water pump on 3.7L/4.7L engines is bolted
directly to the engine timing chain case cover.
(1) Disconnect the negative battery cable.
(2) Drain cooling system (Refer to 7 - COOLING -
STANDARD PROCEDURE).
(3) Remove fan/viscous fan drive assembly from
water pump (Fig. 46) (Refer to 7 - COOLING/EN-
GINE/FAN DRIVE VISCOUS CLUTCH - REMOV-
AL). Do not attempt to remove fan/viscous fan drive
assembly from vehicle at this time.
WARNING: CONSTANT TENSION HOSE CLAMPS
ARE USED ON MOST COOLING SYSTEM HOSES.WHEN REMOVING OR INSTALLING, USE ONLY
TOOLS DESIGNED FOR SERVICING THIS TYPE OF
CLAMP. ALWAYS WEAR SAFETY GLASSES WHEN
SERVICING CONSTANT TENSION CLAMPS.
CAUTION: A number or letter is stamped into the
tongue of constant tension clamps. If replacement
is necessary, use only an original equipment clamp
with matching number or letter and width.
(4) If the water pump is being replaced, do not
unbolt the fan blade assembly from the thermal vis-
cous fan drive.
(5) Remove the radiator fan (Refer to 7 - COOL-
ING/ENGINE/RADIATOR FAN - REMOVAL).
(6) Remove accessory drive belt (Fig. 47) (Refer to
7 - COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(7) Remove the lower radiator hose clamp and
remove the lower hose at the water pump.
(8) Remove the water pump mounting bolts.
Fig. 44 Water Pump and Timing Chain Cover
1 - INTEGRAL WATER PUMP PULLEY
2 - TIMING CHAIN COVER
3 - THERMOSTAT HOUSING
4 - HEATER HOSE FITTINGS
5 - WATER PUMP
Fig. 45 Water/Coolant Bypass Flow and Thermostat
1 - FROM HEATER AND DEGAS CONTAINER
2 - FROM RADIATOR
3 - TO WATER PUMP
4 - ENGINE BYPASS
5 - THERMOSTAT
DRENGINE 7 - 65
WATER PUMP - 3.7L/4.7L (Continued)

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. 49) 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 byantifreeze in the coolant mixture. Additional lubrica-
tion is not necessary.
OPERATION
The diesel engine water pump draws coolant from
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. 50).
(5) Clean water pump sealing surface on cylinder
block.
CLEANING
Clean gasket mating surfaces as necessary.
Fig. 49 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
Fig. 50 Water Pump Removal/Installation
1 - O-RING SEAL (SQUARE)
2 - WATER PUMP
3 - BOLT (2)
DRENGINE 7 - 67
WATER PUMP - 3.7L/4.7L (Continued)

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. 51).
(2) Install water pump. Tighten mounting bolts to
24 N´m (18 ft. lbs.) torque.
(3) Install accessory drive belt. Refer to procedure
in this group.
(4) Install the bolt retaining the wiring harness
near top of water pump.
(5) Fill cooling system. Refer to Refilling Cooling
System in this section.
(6) Connect both battery cables.
(7) Start and warm the engine. Check for leaks.
WATER PUMP INLET TUBE -
5.9L
REMOVAL
REMOVAL - WATER PUMP BYPASS HOSE
WITH AIR CONDITIONING
If equipped with A/C, the generator and A/C com-
pressor along with their common mounting bracket
(Fig. 52) must be partially removed. Removing thegenerator or A/C compressor from their mounting
bracket is not necessary. Also, discharging the A/C
system is not necessary.Do notremove any refriger-
ant lines from A/C compressor.
WARNING: THE A/C SYSTEM IS UNDER PRESSURE
EVEN WITH THE ENGINE OFF. REFER TO REFRIG-
ERANT WARNINGS IN SECTION 24 - HEATING AND
AIR CONDITIONING.
(1) Disconnect the negative battery cable.
(2) Partially drain the cooling system (Refer to 7 -
COOLING - STANDARD PROCEDURE).Do not
waste reusable coolant. If the solution is clean, drain
the coolant into a clean container for reuse.
(3) Remove the upper radiator hose clamp at the
radiator. A special clamp tool must be used to remove
the constant tension clamps. Removethe hose at the
radiator.
(4) Unplug the wiring harness from the A/C com-
pressor.
(5) Remove the air cleaner assembly.
(6) Remove the accessory drive belt (Refer to 7 -
COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL).
(7) The drive belt idler pulley must be removed to
gain access to one of the A/C compressor/generator
bracket mounting bolts. Remove the idler pulley bolt
and remove idler pulley (Fig. 53).
(8) Remove the engine oil dipstick tube mounting
bolt at the side of the A/C-generator mounting
bracket.
(9) Disconnect the throttle body control cables.
Fig. 51 Pump O-ring Seal
1 - O-RING SEAL
2 - GROOVE
3 - WATER PUMP
Fig. 52 Generator - A/C Compressor Mounting
Bracket - Typical
7 - 68 ENGINEDR
WATER PUMP - 5.9L DIESEL (Continued)