OPERATION
OPERATION - COOLING SYSTEM
The engine cooling systems primary purpose is to
maintain engine temperature in a range that will
provide satisfactory engine performance and emission
levels under all expected driving conditions. It also
provides hot water (coolant) for heater performance
and cooling for automatic transmission oil. It does
this by transferring heat from engine metal to cool-
ant, moving this heated coolant to the radiator, and
then transferring this heat to the ambient air.
²When engine is cold: thermostat is closed, cool-
ing system has no flow through the radiator. The
coolant bypass flows through the engine only.
²When engine is warm: thermostat is open, cool-
ing system has bypass flow and coolant flow through
radiator.
Coolant flow circuits for the 2.4L and 3.3/3.8L
engines are shown in (Fig. 2).
OPERATION - HOSE CLAMPS
The spring type hose clamp applies constant ten-
sion on a hose connection. To remove a spring type
hose clamp, use Special Tool 6094 or equivalent, con-
stant tension clamp pliers (Fig. 3) to compress the
hose clamp.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - COOLING SYSTEM
LEAK TEST
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.
Fig. 2 Cooling System Flow
1 - HEATER - REAR (3.3/3.8L OPTIONAL EQUIPMENT) 6 - WATER PUMP
2 - HEATER - FRONT 7 - RADIATOR
3 - ENGINE 8 - COOLANT RECOVERY/RESERVE CONTAINER
4 - THERMOSTAT 9 - COOLANT FLOW - PRESSURE CAP VACUUM
5 - ENGINE OIL COOLER (3.3/3.8L OPTIONAL EQUIPMENT) 10 - COOLANT FLOW - PRESSURE CAP RELIEF
7 - 2 COOLINGRS
COOLING (Continued)
With engine not running, remove radiator pressure
cap and wipe the radiator filler neck sealing seat
clean. The radiator should be full.
Attach the Cooling System Tester 7700 or equiva-
lent to the radiator, as shown in (Fig. 4) and apply
104 kPa (15 psi) pressure. If the pressure drops more
than 13.8 kPa (2 psi) in 2 minutes, inspect all points
for external leaks.
All radiator and heater hoses should be shaken
while at 104 kPa (15 psi), since some leaks occur only
while driving due to engine movement.If there are no external leaks, after the gauge dial
shows a drop in pressure, detach the tester. Start
engine and run until the thermostat opens, allowing
the coolant to expand. Reattach the cooling system
tester. If the needle on the dial fluctuates it indicates
a combustion leak, usually a head gasket leak.
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, raise
the engine rpm a few times. If an abnormal amount
of coolant or steam emits from the tailpipe, 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.
DIAGNOSIS AND TESTING - COOLING SYSTEM
FLOW CHECK
To determine whether coolant is flowing through
the cooling system, use one of the following proce-
dures:
PREFERRED METHOD
WARNING: DO NOT REMOVE THE COOLING SYS-
TEM PRESSURE CAP OR ANY HOSE WITH THE
SYSTEM HOT AND UNDER PRESSURE BECAUSE
SERIOUS BURNS FROM COOLANT CAN OCCUR.
²Remove pressure cap when engine is cold.
Remove small amount of coolant. Idle engine until
thermostat opens. You should observe coolant flow
while looking down the filler neck. Once flow is
detected install the pressure cap. Replace removed
coolant into coolant recovery container.
ALTERNATIVE METHOD
²If engine is cold, idle engine until normal oper-
ating temperature is reached. Feel the upper radiator
hose. If it is hot, coolant is circulating.
Fig. 3 Hose Clamp Tool
1 - HOSE CLAMP TOOL 6094
2 - HOSE CLAMP
Fig. 4 Pressure Testing
RSCOOLING7-3
COOLING (Continued)
DIAGNOSIS AND TESTING - COOLING SYSTEM
AERATION
Low coolant level in a cross flow radiator will
equalize in both tanks with engine off. With engine
at running and at operating temperature, the high
pressure inlet tank runs full and the low pressure
outlet tank drops, resulting in cooling system aera-
tion. Aeration will draw air into the water pump
resulting in the following:
²High reading shown on the temperature gauge.
²Loss of coolant flow through the heater core.
²Corrosion in the cooling system.
²Water pump seal may run dry, increasing the
risk of premature seal failure.
²Combustion gas leaks into the coolant can also
cause the above problems.
DIAGNOSIS AND TESTING - COOLING SYSTEM
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 coolant
recovery bottle by thermal expansion of the coolant.
It then escapes to the atmosphere in the coolant
recovery bottle and is replaced with coolant on cool
down.
To effectively deaerate the system, multiple ther-
mal cycles of the system may be required.
NOTE: Deaeration does not occur at engine idleÐ
higher engine speeds are required. Normal driving
will deaerate cooling system.
STANDARD PROCEDURE
STANDARD PROCEDURE - COOLING SYSTEM
DRAINING
WARNING: DO NOT REMOVE OR LOOSEN THE
COOLANT PRESSURE CAP, CYLINDER BLOCK
DRAIN PLUGS, OR THE DRAINCOCK WHEN THE
SYSTEM IS HOT AND UNDER PRESSURE
BECAUSE SERIOUS BURNS FROM THE COOLANT
CAN OCCUR.
(1)Without removing radiator pressure cap
and with system not under pressure, using a
screwdriver, open the draincock. The draincock is
located on the lower left side of radiator.
(2) After the coolant recovery/reserve container is
empty, then remove coolant pressure cap (Fig. 5).
(3) Remove the cylinder block drain plug(s).
STANDARD PROCEDURE - COOLING SYSTEM
FILLING
Remove radiator pressure cap (Fig. 5) and fill sys-
tem, using a 50/50 mix of MopartAntifreeze/Coolant,
5 Year/100,000 Mile Formula and distilled water.
Continue filling system until full.Be careful not
to spill coolant on drive belts or the generator.
For cooling system capacity, (Refer to LUBRICATION
& MAINTENANCE/FLUID CAPACITIES - SPECIFI-
CATIONS).
Fill coolant recovery/reserve container (Fig. 5) to at
least the MAX mark with 50/50 solution. It may be
necessary to add coolant to the recovery/reserve con-
tainer after three or four warm up/cool down cycles
to maintain coolant level between the MAX and MIN
mark. This will allow trapped air to be removed from
the system.
STANDARD PROCEDURE - ADDING
ADDITIONAL COOLANT
The radiator cap should not be removed.
When additional coolant is needed to maintain this
level, it should be added to the coolant recovery/re-
serve container (Fig. 5). Use only 50/50 mix of ethyl-
ene glycol type antifreeze and distilled water. For the
recommeded antifreeze/coolant type (Refer to LUBRI-
CATION & MAINTENANCE/FLUID TYPES -
DESCRIPTION).
CAUTION: Do not use well water, or suspect water
supply in cooling system. A 50/50 ethylene glycol
and distilled water mix is recommended. For the
recommeded antifreeze/coolant type (Refer to
LUBRICATION & MAINTENANCE/FLUID TYPES -
DESCRIPTION).
STANDARD PROCEDURE - COOLANT LEVEL
CHECK
NOTE: 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 recovery/reserve container (Fig. 5). The
coolant level should be between the MIN and MAX
marks.
7 - 4 COOLINGRS
COOLING (Continued)
CONDITION POSSIBLE CAUSES CORRECTIONS
BELT ROLLED OVER IN GROOVE
OR BELT JUMPS OFF1. Broken cord in belt 1. Replace belt
2. Belt too loose, or too tight 2. (a) Replace belt (auto-tensioned
belts.)
(b) Adjust power steering belt
tension (4 cyl. engine)
3. Misaligned pulleys 3. Align accessories
4. Non-uniform groove or eccentric
pulley4. Replace pulley
CLEANING
Clean all foreign debris from belt pulley grooves.
The belt pulleys must be free of oil, grease, and cool-
ants before installing the drive belt.
INSPECTION
Belt replacement under any or all of the following
conditions is required:
²Excessive wear
²Frayed cords
²Severe glazing
Poly-V Belt system may develop minor cracks
across the ribbed side (due to reverse bending). These
minor cracks are considered normal and acceptable.
Parallel cracks are not (Fig. 1).
NOTE: Do not use any type of belt dressing or
restorer on Poly-V Belts.
DRIVE BELTS - 2.4L
STANDARD PROCEDURE - CHECKING POWER
STEERING BELT TENSION
WARNING: DO NOT CHECK BELT TENSION WITH
ENGINE RUNNING.
Accessory drive belt tension can be measured with
Special Tool 8371 ± Belt Tension Gauge Adapter, and
the DRBIIItusing the following procedures:
(1) Connect 8371 to the DRBIIItfollowing the
instructions provided with tool.
(2) Place end of microphone probe approximately
2.54 cm (1 in.) from belt at belt center span location
shown in (Fig. 2).
(3) Pluck the belt a minimum of 3 times. (Use your
finger or other suitable tool) The frequency of the
belt in hertz (Hz) will display on DRBIIItscreen.
(4) Adjust belt to obtain proper frequency (ten-
sion). Refer to ACCESSORY DRIVE BELT TENSION
CHART for belt tension specifications.
ACCESSORY DRIVE BELT TENSION CHART -
2.4L
Accessory Drive Belt Belt Tension
Air Conditioning
Compressor/GeneratorDynamic Tensioner
Power Steering PumpNew178 - 212
Hz
Used* 145 - 178
Hz
*A belt is considered used after 15 minutes of run-in
time.
Fig. 1 Drive Belt Inspection
1 - NORMAL CRACKS - BELT OK
2 - NOT NORMAL CRACKS - REPLACE BELT
7 - 8 ACCESSORY DRIVERS
DRIVE BELTS (Continued)
REMOVAL
GENERATOR AND AIR CONDITIONING BELT
(1) Raise vehicle on hoist.
(2) Remove the drive belt shield (Fig. 8).
WARNING: DO NOT ALLOW DRIVE BELT TEN-
SIONER TO SNAP BACK, AS DAMAGE TO TEN-
SIONER AND/OR PERSONAL INJURY COULD
RESULT.
(3) Position a wrench on the belt tensioner lug
(Fig. 3).
(4) Release belt tension by rotating the tensioner
clockwise (Fig. 3).
(5) Remove belt.
(1) Carefully return tensioner to its relaxed posi-
tion.
POWER STEERING PUMP
(1) From top of the vehicle, loosen locking nuts (1)
and (2) (Fig. 4).
(2) From under the vehicle, loosen the pivot bolt
(3). Loosen adjusting bolt (4) until belt can be
removed.
INSTALLATION
GENERATOR AND AIR CONDITIONING BELT
(1) Install belt onto all pulleys except for the
crankshaft (Fig. 5).(2) Rotate belt tensioner clockwise until belt can
be installed onto the crankshaft pulley (Fig. 3).
Slowly release belt tensioner.
Fig. 2 Power Steering Belt - Center Span Location
1 - POWER STEERING BELT CENTER SPAN LOCATION
Fig. 3 A/C & GENERATOR BELT TENSION RELEASE
1 - BELT TENSIONER
2 - WRENCH
Fig. 4 Power Steering Pump Belt
1 - REAR LOCKING NUT
2 - FRONT LOCKING NUT
3 - PIVOT BOLT
4 - ADJUSTING BOLT
RSACCESSORY DRIVE7-9
DRIVE BELTS - 2.4L (Continued)
BELT TENSIONER - 2.4L
REMOVAL
(1) Raise vehicle on hoist.
(2) Remove the drive belt shield.
(3) Remove the generator/A/C drive belt. (Refer to
7 - COOLING/ACCESSORY DRIVE/DRIVE BELTS -
REMOVAL)
(4) Remove the belt tensioner (Fig. 7).
INSTALLATION
(1) Install belt tensioner and bolt (Fig. 7). Tighten
bolt to 54 N´m (40 ft. lbs.).
(2) Install generator/A/C compressor drive belt.
(Refer to 7 - COOLING/ACCESSORY DRIVE/DRIVE
BELTS - INSTALLATION)
(3) Install splash shield.
(4) Lower the vehicle.
DRIVE BELTS - 3.3/3.8L
REMOVAL
(1) Raise vehicle on hoist.
(2) Remove the drive belt shield (Fig. 8).
WARNING: DO NOT ALLOW DRIVE BELT TEN-
SIONER TO SNAP BACK, AS DAMAGE TO TEN-
SIONER AND/OR PERSONAL INJURY COULD
RESULT.(3) Position a wrench on the belt tensioner lug
(Fig. 9).
(4) Release belt tension by rotating the tensioner
counterclockwise (Fig. 9).
(5) Remove the drive belt (Fig. 10).
(6) Carefully return tensioner to its relaxed posi-
tion.
Fig. 7 Belt Tensioner - 2.4L
1 - BELT TENSIONER
2 - GENERATOR BRACKET
3 - BOLT
Fig. 8 Accessory Drive Belt Shield
1 - ATTACHING SCREW
2 - ATTACHING SCREWS
3 - SPLASH SHIELD
Fig. 9 DRIVE BELT TENSION RELEASE
1 - BELT TENSIONER LUG
2 - WRENCH
RSACCESSORY DRIVE7-11
COOLANT
DESCRIPTION - ENGINE COOLANT
WARNING: ANTIFREEZE IS AN ETHYLENE GLYCOL
BASE COOLANT AND IS HARMFUL IF SWAL-
LOWED OR INHALED. IF SWALLOWED, DRINK
TWO GLASSES OF WATER AND INDUCE VOMIT-
ING. IF INHALED, MOVE TO FRESH AIR AREA.
SEEK MEDICAL ATTENTION IMMEDIATELY. DO NOT
STORE IN OPEN OR UNMARKED CONTAINERS.
WASH SKIN AND CLOTHING THOROUGHLY AFTER
COMING IN CONTACT WITH ETHYLENE GLYCOL.
KEEP OUT OF REACH OF CHILDREN. DISPOSE OF
GLYCOL BASE COOLANT PROPERLY, CONTACT
YOUR DEALER OR GOVERNMENT AGENCY FOR
LOCATION OF COLLECTION CENTER IN YOUR
AREA. DO NOT OPEN A COOLING SYSTEM WHEN
THE ENGINE IS AT OPERATING TEMPERATURE OR
HOT UNDER PRESSURE, PERSONAL INJURY CAN
RESULT. AVOID RADIATOR COOLING FAN WHEN
ENGINE COMPARTMENT RELATED SERVICE IS
PERFORMED, PERSONAL INJURY CAN RESULT.
CAUTION: Use of Propylene Glycol based coolants
is not recommended, as they provide less freeze
protection and less boiling protection.
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 and
engine block. Then coolant carries the heat to the
radiator where the tube/fin radiator can transfer the
heat to the air.
The use of aluminum cylinder blocks, cylinder
heads, and water pumps requires special corrosion
protection. MopartAntifreeze/Coolant, 5
Year/100,000 Mile Formula (MS-9769), or the equiva-
lent ethylene glycol base coolant with hybrid organic
corrosion inhibitors (called HOAT, for Hybrid Organic
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% Ethylene Glycol and 50% distilled
water to obtain a freeze point of -37ÉC (-35ÉF). If it
loses color or becomes contaminated, drain, flush,
and replace with fresh properly mixed coolant solu-
tion.
The green coolantMUST NOT BE MIXEDwith
the orange or magenta coolants. When replacing cool-
ant the complete system flush must be performed
before using the replacement coolant.CAUTION: MoparTAntifreeze/Coolant, 5
Year/100,000 Mile Formula (MS-9769) may not be
mixed with any other type of antifreeze. Doing so
will reduce the corrosion protection and may result
in premature water pump seal failure. If non-HOAT
coolant is introduced into the cooling system in an
emergency, it should be replaced with the specified
coolant as soon as possible.
DIAGNOSIS AND TESTING - COOLANT
CONCENTRATION TESTING
Coolant concentration should be checked when any
additional coolant was added to system or after a
coolant drain, flush and refill. The coolant mixture
offers optimum engine cooling and protection against
corrosion when mixed to a freeze point of -37ÉC
(-34ÉF) to -46ÉC (-50ÉF). The use of a hydrometer or a
refractometer can be used to test coolant concentra-
tion.
A hydrometer will test the amount of glycol in a
mixture by measuring the specific gravity of the mix-
ture. The higher the concentration of ethylene glycol,
the larger the number of balls that will float, and
higher the freeze protection (up to a maximum of
60% by volume glycol).
A refractometer (Special Tool 8286)(Refer to 7 -
COOLING - SPECIAL TOOLS) will test the amount
of glycol in a coolant mixture by measuring the
amount a beam of light bends as it passes through
the fluid.
Some coolant manufactures use other types of gly-
cols into their coolant formulations. Propylene glycol
is the most common new coolant. However, propylene
glycol based coolants do not provide the same freez-
ing protection and corrosion protection and is not rec-
ommended.
CAUTION: Do not mix types of coolantÐcorrosion
protection will be severely reduced.
STANDARD PROCEDURE - COOLANT SERVICE
For engine coolant recommended service schedule,
(Refer to LUBRICATION & MAINTENANCE/MAIN-
TENANCE SCHEDULES - DESCRIPTION).
RSENGINE7-19
DIAGNOSIS AND TESTING - ENGINE BLOCK
HEATER TESTING
If unit does not operate, trouble can be in either
the power cord or the heater element. Test power
cord for continuity with a 110-volt voltmeter or 110-
volt test light; test heater element continuity with an
ohmmeter or 12-volt test light.
REMOVAL
(1) Drain coolant from radiator and cylinder block.
(Refer to 7 - COOLING - STANDARD PROCEDURE)
(2) Disconnect the power cord plug from heater.
(3) Loosen screw in center of heater. Remove the
heater assembly.
INSTALLATION
(1) Clean block core hole and heater seat.
(2) Insert heater assembly with element loop posi-
tionedupward.
(3) With heater seated, tighten center screw
securely to assure a positive seal.
(4) Install power cord plug to heater.
(5) Fill cooling system with coolant to the proper
level. (Refer to 7 - COOLING - STANDARD PROCE-
DURE)
ENGINE COOLANT
TEMPERATURE SENSOR - 2.4L
DESCRIPTION
The engine coolant temperature sensor threads
into the top of the thermostat housing (Fig. 3). New
sensors have sealant applied to the threads.
REMOVAL
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
(1) Drain the cooling system below thermostat
level. (Refer to 7 - COOLING - STANDARD PROCE-
DURE)
(2) Disconnect coolant temperature sensor electri-
cal connector.
(3) Remove coolant temperature sensor (Fig. 3).
INSTALLATION
(1) Install coolant temperature sensor (Fig. 3).
Tighten sensor to 7 N´m (60 in. lbs.).
(2) Connect electrical connector to sensor.
(3) Fill cooling system. (Refer to 7 - COOLING -
STANDARD PROCEDURE)
ENGINE COOLANT
TEMPERATURE SENSOR -
3.3/3.8L
DESCRIPTION
The engine coolant temperature sensor threads
into a coolant passage on lower intake manifold near
the thermostat (Fig. 6). New sensors have sealant
applied to the threads.
REMOVAL
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING. COOLING SYSTEM
MUST BE PARTIALLY DRAINED BEFORE REMOV-
ING THE COOLANT TEMPERATURE SENSOR.
Fig. 3 Engine Coolant Temperature Sensor - 2.4L
1 - MAP SENSOR
2 - COOLANT TEMPERATURE SENSOR
RSENGINE7-21
ENGINE BLOCK HEATER (Continued)