COOLING SYSTEM
The cooling system has a radiator, coolant, electric fan
motor, shroud, pressure cap, thermostat, coolant reserve
system, transmission oil cooler, a water pump to circulate
the coolant, hoses, and clamps to complete the circuit.
²When Engine is cold: thermostat is closed, cool-
ing system has no flow through the radiator. The
coolant bypass flows through the engine only.
²
When Engine is warm: thermostat is open, cooling
system has bypass flow and coolant flow through radia-
tor.
Its primary purpose is to maintain engine temper-
ature in a range that will provide satisfactory engine
performance and emission levels under all expected
driving conditions. It also provides hot water (cool-
ant) for heater performance and cooling for automatic
transmission oil. It does this by transferring heat
from engine metal to coolant, moving this heated
coolant to the radiator, and then transferring this
heat to the ambient air.
Coolant flow circuits for 2.4L and 3.3/3.8L engines
are shown in (Fig. 1), and 3.0L engine coolant rout-
ing is shown in (Fig. 2)
Fig. 1 Cooling System Operation 2.4L and 3.3/3.8L Engines
Fig. 2 Cooling System Operation 3.0L Engine
7 - 2 COOLING SYSTEMNS
GENERAL INFORMATION (Continued)
COOLANT RECOVERY SYSTEM (CRS)
This system works with the radiator pressure cap
to use thermal expansion and contraction of the cool-
ant to keep the coolant free of trapped air. Provides a
convenient and safe method for checking coolant
level and adjusting level at atmospheric pressure
without removing the radiator pressure cap. It also
provides some reserve coolant to cover deaeration
and evaporation or boiling losses. All vehicles are
equipped with this system and take various shapes
and forms. (Fig. 3) shows a typical system in the typ-
ical location.
See Coolant Level Service, and Deaeration, and
Pressure Cap sections for operation and service.
AUTOMATIC TRANSMISSION OIL COOLERÐ2.4L
Oil cooler is internal oil to coolant type, mounted
in the radiator left tank (Fig. 4). Rubber oil lines feed
the oil cooler and the automatic transmission. Use
only approved transmission oil cooler hose. Since
these are molded to fit space available, molded hoses
are recommended.
ENGINE THERMOSTAT
The engine cooling thermostats are a wax pellet
driven, reverse poppet choke type. They are designed
to provide the fastest warm up possible by prevent-
ing leakage through them and to guarantee a mini-
mum engine operating temperature of 88 to 93ÉC
(192 to 199ÉF). They also automatically reach wide
open so they do not restrict flow to the radiator as
temperature of the coolant rises in hot weather to
around 104ÉC (220ÉF). Above this temperature the
coolant temperature is controlled by the fan, the
radiator, and the ambient temperature, not the ther-
mostat.
WATER PUMPS
A quick test to tell whether the pump is working is
to see if the heater warms properly. A defective pump
can not circulate heated coolant through the long
heater hose.The water pump on all models can
be replaced without discharging the air condi-
tioning system.
COOLANT
The cooling system is designed around the coolant.
The coolant must accept heat from engine metal, in
the cylinder head area near the exhaust valves. Cool-
ant then carries this heat to the radiator, where the
tube/fin assemblies of these components can give it
up to the air.
The use of aluminum cylinder heads, intake mani-
folds, and water pumps requires special corrosion
protection. MopartAntifreeze or the equivalent is
recommended for best engine cooling without corro-
sion, when mixed only to a freeze point of -37ÉC
(-35ÉF) to -59ÉC (-50ÉF). If it loses color or becomes
contaminated, drain, flush, and replace with fresh
properly mixed solution.
CAUTION: Do not use well water, or suspect water
supply in cooling system. A 50/50 ethylene glycol
and distilled water mix is recommended.
RADIATOR
The radiators are cross-flow types (horizontal
tubes) with design features that provide greater
strength along with sufficient heat transfer capabili-
Fig. 3 Coolant Recovery System
Fig. 4 Automatic Transmission Oil Cooler
NSCOOLING SYSTEM 7 - 3
GENERAL INFORMATION (Continued)
WARNING: WITH TOOL IN PLACE, PRESSURE
WILL BUILD UP FAST. EXCESSIVE PRESSURE
BUILT UP, BY CONTINUOUS ENGINE OPERATION,
MUST BE RELEASED TO A SAFE PRESSURE
POINT. NEVER PERMIT PRESSURE TO EXCEED 138
kPa (20 psi).
If the needle on the dial does not fluctuate, race
the engine a few times. If an abnormal amount of
coolant or steam emits from the tail pipe, it may
indicate a coolant leak caused by a faulty head gas-
ket, cracked engine block, or cracked cylinder head.
There may be internal leaks that can be deter-
mined by removing the oil dipstick. If water globules
appear intermixed with the oil it will indicate an
internal leak in the engine. If there is an internal
leak, the engine must be disassembled for repair.
RADIATOR CAP TO FILLER NECK SEAL PRESSURE
RELIEF CHECK
The pressure cap upper gasket (seal) pressure
relief can be checked by removing the overflow hose
at the radiator filler neck nipple (Fig. 13). Attach the
Radiator Pressure Tool to the filler neck nipple and
pump air into the radiator. Pressure cap upper gas-
ket should relieve at 69-124 kPa (10-18 psi) and hold
pressure at 55 kPa (8 psi) minimum.
WARNING: THE WARNING WORDS ªDO NOT
OPEN HOTº ON THE RADIATOR PRESSURE CAP IS
A SAFETY PRECAUTION. WHEN HOT, PRESSURE
BUILDS UP IN COOLING SYSTEM. TO PREVENT
SCALDING OR INJURY, THE RADIATOR CAP
SHOULD NOT BE REMOVED WHILE THE SYSTEM
IS HOT OR UNDER PRESSURE.
There is no need to remove the radiator cap at any
timeexceptfor the following purposes:
(1) Check and adjust coolant freeze point. By add-
ing or subtracting coolant through CRS bottle.
(2) Refill system with new coolant.
(3) Conducting service procedures.
(4) Checking for vacuum leaks.WARNING: IF VEHICLE HAS BEEN RUN
RECENTLY, WAIT 15 MINUTES BEFORE REMOVING
CAP. THEN PLACE A SHOP TOWEL OVER THE CAP
AND WITHOUT PUSHING DOWN ROTATE COUN-
TERCLOCKWISE TO THE FIRST STOP. ALLOW FLU-
IDS TO ESCAPE THROUGH THE OVERFLOW TUBE
AND WHEN THE SYSTEM STOPS PUSHING COOL-
ANT AND STEAM INTO THE CRS TANK AND PRES-
SURE DROPS PUSH DOWN AND REMOVE THE CAP
COMPLETELY. SQUEEZING THE RADIATOR INLET
HOSE WITH A SHOP TOWEL (TO CHECK PRES-
SURE) BEFORE AND AFTER TURNING TO THE
FIRST STOP IS RECOMMENDED.
PRESSURE TESTING RADIATOR CAP
Dip the pressure cap in water, clean any deposits
off the vent valve or its seat and apply cap to end of
Radiator Pressure Tool. Working the plunger, 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 cap. SeeCAUTION.
If the pressure cap tests properly while positioned
on Radiator Pressure Tool (Fig. 14), but will not hold
pressure or vacuum when positioned on the radiator.
Inspect the radiator filler neck and cap top gasket for
irregularities that may prevent the cap from sealing
properly.
CAUTION: Radiator Pressure Tool is very sensitive
to small air leaks that will not cause cooling system
problems. A pressure cap that does not have a his-
tory of coolant loss should not be replaced just
because it leaks slowly when tested with this tool.
Add water to the tool. Turn tool upside down and
recheck pressure cap to confirm that cap is bad.
LOW COOLANT LEVEL AERATION
Low coolant level in a cross flow radiator will
equalize in both tanks with engine off. With engine
Fig. 13 Radiator Pressure Cap Filler Neck
Fig. 14 Pressure Testing Radiator Cap
NSCOOLING SYSTEM 7 - 15
DIAGNOSIS AND TESTING (Continued)
at running operating temperature the high pressure
inlet tank runs full and the low pressure outlet tank
drops:
²Transmission oil will become hotter.
²High reading shown on the temperature gauge.
²Air in the coolant can cause loss of flow through
the heater.
²Exhaust gas leaks into the coolant also can
cause the same problems.
DEAERATION
Air can only be removed from the system by gath-
ering under the pressure cap. On the next heat up it
will be pushed past the pressure cap into the CRS
tank by thermal expansion of the coolant. It then
escapes to the atmosphere in the CRS tank and is
replaced with solid coolant on cool down.
TEMPERATURE GAUGE INDICATION
At idle with Air Conditioning off the temperature
gauge will rise slowly to about 5/8 gauge travel, the
fan will come on and the gauge will quickly drop to
about 1/2 gauge travel. This is normal.
SERVICE PROCEDURES
COOLANT LEVEL CHECKÐROUTINE
Do not remove radiator cap for routine cool-
ant level inspections.
The coolant reserve system provides a quick visual
method for determining the coolant level without
removing the radiator cap.With the engine cold
and not running,simply observe the level of the
coolant in the reserve tank (Fig. 3). The coolant level
should be between the minimum and maximum
marks.
COOLANTÐADDING ADDITIONAL
The radiator cap should not be removed.
When additional coolant is needed to maintain this
level, it should be added to the coolant reserve tank.
Use only 50/50 mix of ethylene glycol type antifreeze
and water.
CAUTION: Do not use well water, or suspect water
supply in cooling system. A 50/50 ethylene glycol
and distilled water mix is recommended.
COOLANT LEVEL SERVICE
The cooling system is closed and designed to main-
tain coolant level to the top of the radiator.
When servicing requires a coolant level check in
the radiator, the engine must beoffandnotunder
pressure. Drain several ounces of coolant from the
radiator draincock while observing the CoolantRecovery System (CRS) Tank. Coolant level in the
CRS tank should drop slightly. Then remove the radi-
ator cap. The radiator should be full to the top. If
not, and the coolant level in the CRS tank is at the
MIN mark there is an air leak in the CRS system.
Check hose or hose connections to the CRS tank,
radiator filler neck or the pressure cap seal to the
radiator filler neck for leaks.
COOLING SYSTEMÐDRAINING
Without removing radiator pressure cap and
with system not under pressure,shut engine off
and open draincock. The coolant reserve tank should
empty first, then remove radiator pressure cap. (if
not, see Testing Cooling System for leaks). To vent
2.4L engine remove the coolant temperature sensor
located above water outlet housing (Fig. 15). The 3.0/
3.3/3.8L engines have an air bleed vent on the ther-
mostat.
Removal of a sensor is required because the ther-
mostat does not have an air vent. Sensor removal
allows an air bleed for coolant to drain from the
engine block.
COOLING SYSTEMÐREFILLING
First clean system to remove old coolant, see Cool-
ing System Cleaning.
Fill the system, using the correct antifreeze as
described in the Coolant Section. Fill the system to
50 percent of its capacity with 100 percent glycol.
Then complete filling system with water. The 2.4L
engine requires venting by removal of the coolant
sensor on top of the water outlet connector (Fig. 15).
When coolant reaches this hole:
²Install coolant sensor and tighten to 7 N´m (60
in. lbs.) for 2.4L Engines.
Fig. 15 Coolant Temperature SensorÐ2.4L Engine
Drain/Fill
7 - 16 COOLING SYSTEMNS
DIAGNOSIS AND TESTING (Continued)
INSTALLATION
(1) Clean all gasket and O-ring surfaces on pump
and water pipe inlet tube.
(2) Install new O-ring on water inlet pipe (Fig.
22). Wet the O-ring (with water) to ease assembly.
CAUTION: Keep the O-ring free of oil or grease.
(3) Install new gasket on water pump and install
pump inlet opening over water pipe, press assembly
to cause water pipe insertion into pump housing.
(4) Install pump to block mounting bolts and
tighten to 27 N´m (20 ft. lbs.).
(5) See Timing Belt in Engine, Group 9 and
install timing belt. Reassemble engine.
(6) Fill cooling system. See Refilling Cooling Sys-
tem.
WATER PUMPÐ3.3/3.8L ENGINES
REMOVAL
(1) Drain Cooling System. Refer to Draining Cool-
ing System in this group.
(2) Remove Poly-V Drive Belt.
(3) Remove right front lower fender shield.
(4) Remove pump pulley bolts and remove pulley.
(5) Remove pump mounting screws (Fig. 23).
Remove water pump.
(6) Remove and discard O-ring seal.
(7) Clean O-ring groove and O-ring surfaces on
pump and chain case cover. Take care not to scratch
or gouge sealing surface.
INSTALLATION
(1) Install new O-ring into groove (Fig. 24).
(2) Install pump to chain case cover. Torque
screws to 12 N´m (105 in. lbs.)
(3) Rotate pump by hand to check for freedom of
movement.(4) Position pulley on pump. Install screws and
torque to 30 N´m (250 in. lbs.).
(5) Install drive belt. See Accessory Drive Belts in
this group.
(6) Install right front lower fender shield.
(7) Refill Cooling System. See Refilling Cooling
System.
THERMOSTATÐ2.4L ENGINE
REMOVAL
(1) Drain cooling system down below the thermo-
stat level. Refer to Draining Cooling System in this
group.
(2) Remove thermostat housing bolts and housing
(Fig. 25).
(3) Remove thermostat, discard gasket and clean
both gasket sealing surfaces.
Fig. 23 Water Pump Ð3.3/3.8L Engines
Fig. 24 Water Pump Body
Fig. 25 Thermostat, Housing, and Outlet
ConnectorÐ2.4L Engine
NSCOOLING SYSTEM 7 - 19
REMOVAL AND INSTALLATION (Continued)
INSTALLATION
(1) Place a new gasket (dipped in water) on the
thermostat housing surface, center thermostat into
opening in the intake manifold water box.
(2) Place housing and gasket over the thermostat,
making sure thermostat is in the recess provided
(Fig. 28).
(3) Bolt housing to intake manifold, tighten bolts
to 28 N´m (250 in. lbs.).
(4) Refill the cooling system to the proper level.
Refer to Cooling System Refilling outlined in this sec-
tion for procedure.
RADIATOR
REMOVAL
(1) Disconnect negative cable from battery.
WARNING: DO NOT REMOVE THE CYLINDER
BLOCK PLUG OR THE RADIATOR DRAINCOCK
WITH THE SYSTEM HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM COOLANT CAN
OCCUR.
(2) Drain cooling system. Refer to Draining Cool-
ing System of this section.
(3) Remove air intake resonator.
(4) Remove coolant reserve system tank to filler
neck tube hose.
(5) Disconnect fans from the connector located on
the left side of the fan module.
(6) Remove the Coolant Recovery System (CRS)
tank retaining screw from the upper radiator closure
panel crossmember.
(7) Disconnect the upper radiator mounting
screws from the crossmember. Disconnect the engine
block heater wire if equipped.
(8) Remove the upper radiator closure panel
crossmember. Refer to Group 23 Body for procedure.
(9) Remove air cleaner assembly.
(10) Disconnect automatic transmission oil cooler
lines at radiator and plug.
(11) Disconnect inlet and outlet hoses from the
radiator. Remove the lower hose clip from the fan
module.
(12) Remove A/C condenser fasteners and sepa-
rate the condenser from the radiator (Fig. 29). Verify
the condenser is supported in position.
(13) Remove A/C filter/dryer mounting bracket, 2
bolts to the fan module, and 2 nuts to the filter/dryer.
(14) Radiator can now be lifted free from engine
compartment.Care should be taken not to dam-
age radiator cooling fins or water tubes during
removal.INSTALLATION
(1)Be sure the air seals are in position before
radiator is installed.Slide radiator down into posi-
tion behind closure panel. Seat the radiator with the
rubber isolators into the mounting holes provided,
with a 10 lbs. force.
(2) Install A/C filter/dryer and mounting bracket
onto fan module.
(3) Install Air Conditioning Condenser onto the
radiator (Fig. 29).
(4) Unplug and connect automatic transmission
oil cooler lines to radiator.
(5) Install inlet and outlet radiator hoses (includ-
ing coolant reserve hose) and connect the fan motor
electrical connection.
(6) Install air cleaner assembly.
(7) Install the upper radiator closure panel cross-
member. Refer to Group 23 Body for procedure.
(8) Install the upper radiator mounting screws.
Tighten radiator mounting bolts to 12 N´m (105 in.
lbs.). Connect the engine block heater wire if
equipped.
(9) Install the Coolant Recovery System (CRS)
tank retaining screw to the upper radiator closure
panel crossmember.
(10) Install air intake resonator.
(11) Fill cooling system. Refer to Cooling System
Filling in this section.
(12) Connect negative cable to battery.
RADIATOR DRAINCOCK
REMOVAL
CAUTION: Use of pliers on draincock is not rec-
ommended. Damage may occur to part. Draincock
should not be removed unless leakage observed.
(1) Turn the draincock stem counterclockwise to
unscrew the stem. When the stem is unscrewed to
Fig. 29 Air Conditioning Condenser Mounting
Fasteners
NSCOOLING SYSTEM 7 - 21
REMOVAL AND INSTALLATION (Continued)
and the remove the splash shield to gain access to
the drive belts.
BELT TENSION GAUGE METHOD
Use belt tensioning Special Tool Kit C-4162 for:
CAUTION: The Burroughs gauge for the Poly-V
belt is not to be used on the V-belt. These gauges
are not interchangeable.
²For conventional V-belts affix the Burroughs
gauge (Special Tool C-4162) to the belt. Adjust the
belt tension for New or Used belt as prescribed in the
Belt Tension Chart.
²For a Poly-V belt affix the Poly-V Burroughs
gauge to the belt and then apply specified tension to
the belt as prescribed in the Belt Tension Chart
Adjust belt tension for aNeworUsedbelt as pre-
scribed in the Belt Tension Chart.
BELT TENSION CHARTSPECIFICATIONS
COOLING SYSTEM CAPACITY
TORQUE CHART
DESCRIPTION TORQUE
Thermostat Housing
BoltsÐ2.4L & 3.3/3.8L......28N´m(250 in. lbs.)
BoltsÐ3.0L...............12N´m(105 in. lbs.)
Water Pump Mounting
BoltsÐ2.4L & 3.3/3.8L......12N´m(250 in. lbs.)
BoltsÐ3.0L...............27N´m(240 in. lbs.)
Water Pump Inlet Tube
BoltsÐ2.4L...............12N´m(250 in. lbs.)
BoltsÐ3.0L................11N´m(94in.lbs.)
Water Pump Pulley
BoltsÐ3.3/3.8L............28N´m(250 in. lbs.)
Transaxle Oil Cooler Hose
ClampsÐAll Engines.........2N´m(18in.lbs.)
Radiator Mounting Upper Bracket
NutÐAll Engines..........12N´m(105 in. lbs.)
SPECIAL TOOLS
COOLING
ACCESSORY DRIVE
BELTGAUGE
2.4L ENGINE
A/C COMPRESSOR /
GENERATORNEW 190 LB.
USED 115 LB.
POWER STEERING NEW 140 LB.
USED 90 LB.
3.0L ENGINE
A/C COMPRESSOR NEW 150 LB.
USED 80 LB.
GENERATOR / POWER
STEERINGDYNAMIC TENSIONER
3.3/3.8L ENGINES
A/C COMPRESSOR DYNAMIC TENSIONER
GENERATOR / WATER
PUMP / POWER
STEERINGDYNAMIC TENSIONER
Engine Standard Duty Trailer Tow or
Heavy Duty
Front
HeaterRear
HeaterFront
HeaterRear
Heater
2.4L 10.6
liters*
(11.23
qts.)*N/A N/A N/A
3.0L 12.3
liters*
(13.0
qts.)*N/A N/A 15.0
liters*
(15.9
qts.)*
3.3/3.8L 12.5
liters*15.26
liters*12.5
liters*15.26
liters*
(13.23
qts.)*(16.13
qts.)*(13.23
qts.)*(16.13
qts)*
*Includes Heater and Coolant Recovery Tank Filled to
Max Level.
Belt Tension Gauge C-4162
7 - 26 COOLING SYSTEMNS
ADJUSTMENTS (Continued)
COOLING SYSTEM
CONTENTS
page page
GENERAL INFORMATION
COOLANT PRESSURE BOTTLE............ 1
COOLING SYSTEM Ð 2.0L GASOLINE...... 1
COOLING SYSTEM Ð 2.5L VM DIESEL..... 1
LOW COOLANT LEVEL SENSOR........... 1
RADIATOR............................ 2
DESCRIPTION AND OPERATION
AUTOMATIC BELT TENSIONER............ 6
BELT TENSION......................... 5
COOLANT PERFORMANCE............... 5
PRESSURE/VENT CAP................... 4
THERMOSTAT OPERATION............... 4
THERMOSTAT......................... 6
WATER PUMP......................... 3
SERVICE PROCEDURES
ADDING ADDITIONAL COOLANT........... 7
DRAINING COOLING SYSTEM............. 7
REFILLING COOLING SYSTEM............ 7
REMOVAL AND INSTALLATION
ENGINE THERMOSTATÐ 2.0L GASOLINE . . . 9GENERATOR/POWER STEERING BELT Ð 2.5L
VM DIESEL......................... 10
RADIATOR Ð 2.5L VM DIESEL........... 9
THERMOSTAT Ð 2.5L VM DIESEL......... 9
WATER PUMP BELT Ð 2.5L VM DIESEL . . . 10
WATER PUMP Ð 2.0L GASOLINE......... 7
WATER PUMP Ð 2.5L VM DIESEL........ 8
CLEANING AND INSPECTION
WATER PUMP........................ 10
ADJUSTMENTS
BELT TENSION CHART................. 11
BELT TENSION GAUGE METHOD......... 11
SPECIFICATIONS
COOLING SYSTEM CAPACITY............ 12
TORQUE CHART...................... 12
SPECIAL TOOLS
COOLING............................ 12
GENERAL INFORMATION
COOLING SYSTEM Ð 2.0L GASOLINE
The 2.0L gasoline engine cooling system consists of
an engine cooling module, thermostat, coolant, a
water pump to circulate the coolant. The engine cool-
ing module may consist of a radiator, electric fan
motors, fan, shroud, coolant reserve system, hoses,
clamps, air condition condenser.
²When the Engine is cold: The thermostat is
closed; the cooling system has no flow through the
radiator. The coolant flows through the engine,
heater system and bypass.
²When the Engine is warm: Thermostat is open;
the cooling system has flow through radiator, engine,
heater system and bypass.
COOLING SYSTEM Ð 2.5L VM DIESEL
The cooling system has a radiator, coolant, electric
fan motors, shroud, pressure cap, thermostat, coolant
pressure bottle, hoses, a water pump to circulate the
coolant, to complete the circuit. Coolant flow for the
VM diesel engine is shown in (Fig. 1).
COOLANT PRESSURE BOTTLE
2.5L VM DIESEL
This system works with the pressure cap to use
thermal expansion and contraction of the coolant to
keep the coolant free of trapped air. It provides some
reserve coolant to cover minor leaks and evaporation
or boiling losses. The coolant pressure bottle location
for 2.5L diesel is above the cylinder head cover (Fig.
2).
LOW COOLANT LEVEL SENSOR
The low coolant level sensor checks for low coolant
level in the coolant tank. A signal will be sent from
this sensor to the Body Control Module (BCM). When
the BCM determines low coolant level for 30 contin-
uous seconds, the instrument panel mounted low
coolant level warning lamp will be illuminated. The
sensor is located on the front side of the coolant tank
(Fig. 4). For information, refer to Group 8E, Instru-
ment Panel and Gauges.
If this lamp is illuminated, it indicates the need to
fill the coolant tank and check for leaks.
NS/GSCOOLING SYSTEM 7 - 1