If the gasket is dirty or damaged, a vacuum
may not be achieved, resulting is loss of coolant
and eventual overheating due to low coolant
level in radiator and engine.
ENGINE BLOCK HEATER
The engine block heater is available as an optional
accessory on all models. The heater is operated by
ordinary house current (110 Volt A.C.) through a
power cord located behind the radiator grille. This
provides easier engine starting and faster warm-up
when vehicle is operated in areas having extremely
low temperatures. The heater is mounted in a core
hole (in place of a core hole plug) in the engine block,
with the heating element immersed in coolant.
Fig. 7 Cooling ModuleÐ3.0L (Front A/C Only)
Fig. 8 Cooling ModuleÐ3.0/3.3/3.8L (With Rear A/C)
Fig. 9 Radiator Pressure Cap Filler Neck
NSCOOLING SYSTEM 7 - 5
GENERAL INFORMATION (Continued)
DESCRIPTION AND OPERATION
WATER PIPESÐ3.0L ENGINE
The 3.0L engine uses metal piping beyond the
lower radiator hose to route (suction) coolant to the
water pump, which is located in the V of the cylinder
banks (Fig. 10).
These pipes are provided with inlet nipples for
thermostat bypass and heater return coolant hoses,
and brackets for rigid engine attachment. The pipes
employ O-rings for sealing at their interconnection
and to the water pump (Fig. 10).
COOLANT PERFORMANCE
Performance is measurable. For heat transfer pure
water excels (Formula = 1 btu per minute for each
degree of temperature rise for each pound of water).
This formula is altered when necessary additives to
control boiling, freezing, and corrosion are added as
follows:
²Pure Water (1 btu) boils at 100ÉC (212ÉF) and
freezes at 0ÉC (32ÉF)
²100 percent Glycol (.7 btu) can cause a hot
engine and detonation and will lower the freeze point
to -22ÉC (-8ÉF).
²50/50 Glycol and Water (.82 btu) is the recom-
mended combination that provides a freeze point of
-37ÉC (-35ÉF). The radiator, water pump, engine
water jacket, radiator pressure cap, thermostat, tem-
perature gauge, sending unit and heater are all
designed for 50/50 glycol.CAUTION: Do not use well water, or suspect water
supply in cooling system. A 50/50 ethylene glycol
and distilled water mix is recommended.
Where required, a 56 percent glycol and 44 percent
water mixture will provide a freeze point of -59ÉC
(-50ÉF).
CAUTION: Richer mixtures cannot be measured
with field equipment. This can lead to problems
associated with 100 percent glycol.
RADIATOR HOSES AND CLAMPS
WARNING: IF VEHICLE HAS BEEN RUN
RECENTLY, WAIT 15 MINUTES BEFORE WORKING
ON VEHICLE. RELIEVE PRESSURE BY PLACING A
SHOP TOWEL OVER THE CAP AND WITHOUT
PUSHING DOWN ROTATE IT COUNTERCLOCKWISE
TO THE FIRST STOP. ALLOW FLUIDS AND STEAM
TO ESCAPE THROUGH THE OVERFLOW TUBE.
THIS WILL RELIEVE SYSTEM PRESSURE
The hoses are removed by using constant tension
clamp pliers to compress the hose clamp.
A hardened, cracked, swollen or restricted hose
should be replaced. Do not damage radiator inlet and
outlet when loosening hoses.
Radiator hoses should be routed without any kinks
and indexed as designed. The use of molded hoses is
recommended.
Spring type hose clamps are used in all applica-
tions. If replacement is necessary replace with the
original MOPARtequipment spring type clamp.
WATER PUMPÐ2.4L ENGINE
The water pump has a diecast aluminum body and
housing with a stamped steel impeller. The water
pump bolts directly to the block. Cylinder block to
water pump sealing is provided by a rubber O-ring.
The water pump is driven by the timing belt. Refer
to Timing Belt in Group 9, Engine for component
removal providing access to water pump.
WATER PUMPÐ3.0L ENGINE
The pump bolts directly to the engine block, using
a gasket for pump to block sealing (Fig. 11). The
pump is serviced as a unit.
The water pump is driven by the timing belt. See
Timing Belt in Group 9, Engine for component
removal providing access to water pump.
Fig. 10 Engine Inlet Coolant Pipes 3.0L Engine
7 - 6 COOLING SYSTEMNS
WATER PUMPÐ3.3/3.8L ENGINES
The pump has a die cast aluminum body and a
stamped steel impeller. It bolts directly to the chain
case cover, using an O-ring for sealing. It is driven by
the back surface of the Poly-V Drive Belt.
DIAGNOSIS AND TESTING
Fig. 11 Water PumpÐ3.0L Engine
ACCESSORY DRIVE BELT
CONDITION POSSIBLE CAUSES CORRECTIONS
INSUFFICIENT ACCESSORY
OUTPUT DUE TO BELT SLIPPAGE1. Belt too loose 1. Adjust belt tension (4 cyl. engine).
Replace belt (6 cyl. engine)
2. Belt excessively glazed or worn 2. Replace and tighten as specified
BELT SQUEAL WHEN
ACCELERATING ENGINE1. Belts too loose 1. Adjust belt tension (4 cyl. engine).
Replace belt (6 cyl. engine)
2. Belt glazed 2. Replace belts
BELT SQUEAK AT IDLE1. Belts too loose 1. Adjust belt tension (4 cyl. engine).
Replace belt (6 cyl. engine)
2. Dirt or paint imbedded in belt 2. Replace belt
3. Non-uniform belt 3. Replace belt
4. Misaligned pulleys 4. Align accessories
5. Non-uniform groove or eccentric
pulley5. Replace pulley
BELT ROLLED OVER IN GROOVE
OR BELT JUMPS OFF1. Broken cord in belt 1. Replace belt
2. Belt too loose, or too tight 2. Adjust belt tension (4 cyl. engine).
Replace belt (6 cyl. engine)
3. Misaligned pulleys 3. Align accessories
4. Non-uniform groove or eccentric
pulley4. Replace pulley
NSCOOLING SYSTEM 7 - 7
DESCRIPTION AND OPERATION (Continued)
CONDITION - AND CHECKS DIAGNOSIS
Inadequate Air Conditioning Performance - Cooling System Suspected
(1) Check for plugged air side of condenser and
radiator front and rear.(1) Wash out with low-velocity water.
(2) Assure fan runs whenever A/C head pressure
exceeds 1724 kPa (250 psi).(2) Repair as necessary.
(3) Check for missing air seals-recirculating air path.
(4) Assure correct cooling system parts.
Battery Dead - Suspect Fan Current Draw as Cause
(1) With a good, fully charged battery. (1) a - Assure fan control is operating properly.
(1) b - See charging system in Electrical, Group 8B.
Hot Smell - Suspect Cooling System
(1) Was temperature gauge high? (1) a - Yes, See9Gauge Reads High9
(1) b - No. See 2, 3, 4, and 5.
(2) Heat shields all in place? (2) a - Yes, See 3, 4, and 5.
(2) b - Repair or replace heat shields.
(3) Fan control operating properly? (3) a - Yes, See 4 and 5.
(3) b - No, See Radiator Fan Control this section.
(4) Heat exchanger air side plugged? (4) Clean as required.
(5) Engine missing or running rich? (5) Repair as required.
Poor Driveability - Suspect Failed Open Thermostat.
(1) Check diagnostics - is code 17 set? (Engine too
cold for too long)(1) If yes, change thermostat.
Poor Heater Performance - Suspect Failed Open Thermostat
(1) Does gauge read low? (1) See 3
(2) Check coolant level. (2) See 3
(3) Check diagnostics - is code 17 set? (Engine too
cold for too long)(3) If yes, change thermostat. If no, check heater
bypass valve, which should be closed except in Max
A/C or off mode; if not, see Heater and Air Conditioning
Group, 24.
Steaming, Observe Water Vapor Through Grill or Head Gap at Standstill at Idle - In Wet Weather
(1) This is normal. It is moisture, snow, or water on the
outside of the radiator that evaporates when the
thermostat opens to put hot coolant into the radiator.
This usually occurs in cold weather with no fan or air
flow to blow it away.(1) Normal condition - no service required.
NSCOOLING SYSTEM 7 - 13
DIAGNOSIS AND TESTING (Continued)
RADIATOR COOLANT FLOW TEST
To determine whether coolant is flowing through
the cooling system, use the following procedure:
(1) If engine is cold, idle engine until normal oper-
ating temperature is reached. Then feel the upper
radiator hose. If it is hot, coolant is circulating.
WARNING: DO NOT REMOVE RADIATOR PRES-
SURE CAP WITH THE SYSTEM HOT AND UNDER
PRESSURE BECAUSE SERIOUS BURNS FROM
COOLANT CAN OCCUR.
(2) Remove radiator pressure cap when engine is
cold, idle engine until thermostat opens, you should
observe coolant flow while looking down the filler
neck. Once flow is detected install radiator pressure
cap.
RADIATOR FAN CONTROL
Fan control is accomplished two ways. A pressure
transducer on the compressor discharge line sends a
signal to the Powertrain Control Module (PCM)
which will activate the fan. In addition to this con-
trol, the fan is turned on by the temperature of the
coolant which is sensed by the coolant temperature
sensor which sends the message to the PCM. The fan
will not run during cranking until the engine starts
no matter what the coolant temperature is.
CAUTION: The solid state fan relay is attached to
the left frame rail near the lower radiator support.
The relay bracket, and fastener are used to dissi-
pate heat from the relay. Ensure the relay is prop-
erly attached to prevent the following:
²Intermittent engine overheating.
²Relay ªthermalº shutdown, or relay damage.
ELECTRIC FAN MOTOR TEST
Refer to Powertrain Diagnostic Manual for proce-
dure.
TESTING COOLING SYSTEM FOR LEAKS
With engine not running, wipe the radiator filler
neck sealing seat clean. The radiator should be full.
Attach the Radiator Pressure Tool to the radiator,
as shown in (Fig. 12) and apply 104 kPa (15 psi)
pressure. If the pressure drops more than 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 the engine up to normal operating
temperature to open the thermostat and allow the
coolant to expand. Reattach the tester. If the needleon the dial fluctuates it indicates a combustion leak,
usually a head gasket leak.
RADIATOR FAN OPERATION
Radiator Fan Control A/C Pressure
Fan
Operation
Low
Fan
Speed
30%High
Fan
Speed
100%Low
Fan
Speed
30%High
Fan
Speed
100%
On: 104ÉC
(220ÉF)110ÉC
(230ÉF)
Fan
Speed
Duty-
Cycles
(Ramps-
up) from
31% to
99%1,724
Kpa
(250
psi)2,068
Kpa
(300
psi)Fan
Speed
Duty-
Cycles
(Ramps-
up) from
31% to
99%
Off: 101ÉC
(214ÉF)Fan
Speed
Duty-
Cycles
(Ramps-
down)
from
99% to
31%1,710
Kpa
(248
psi)Fan
Speed
Duty-
Cycles
(Ramps-
down)
from
99% to
31%
Fig. 12 Pressure Testing Cooling System
7 - 14 COOLING SYSTEMNS
DIAGNOSIS AND TESTING (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)
Continue filling system until full, this provides bet-
ter heater performance.Be careful not to spill
coolant on drive belts or the generator.
Fill coolant reserve system to at least the MAX
mark with 50/50 solution. It may be necessary to add
coolant to the reserve tank 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.
REMOVAL AND INSTALLATION
WATER PUMPÐ2.4L ENGINE
REMOVAL
(1) Disconnect negative cable from battery.
(2) Raise vehicle on a hoist. Remove right inner
splash shield.
(3) Remove accessory drive belts. Refer to Acces-
sory Drive Belt service in this section.
(4) Drain cooling system. Refer to Cooling System
Draining in this section.
(5) Support engine from the bottom and remove
right engine mount.
(6) Remove right engine mount bracket.
(7) Remove timing belt. Refer to Group 9, Engine
for procedure.
(8) Remove timing belt idler pulley.
(9) Hold camshaft sprocket with Special tool
C-4687 and adaptor C-4687-1 while removing bolt.
Remove both cam sprockets.
(10) Remove rear timing belt cover.
(11) Remove water pump attaching screws to
engine (Fig. 16).
INSTALLATION
(1) Install new O-ring gasket in water pump body
O-ring groove (Fig. 17).
CAUTION: Make sure O-ring is properly seated in
water pump groove before tightening screws. An
improperly located O-ring may cause damage to the
O-ring and cause a coolant leak.(2) Assemble pump body to block and tighten
screws to 12 N´m (105 in. lbs.) (Fig. 16). Pressurize
cooling system to 15 psi with pressure tester and
check water pump shaft seal and O-ring for leaks.
(3) Rotate pump by hand to check for freedom of
movement.
(4) Install rear timing belt cover.
(5) Install camshaft sprockets and torque bolts to
101 N´m (75 ft. lbs.).
(6) Install timing belt idler pulley and torque
mounting bolt to 61 N´m (45 ft. lbs.).
(7) Install timing belt. Refer to Group 9, Engine,
2.4L Timing Belt.
(8) Install right engine mount bracket and engine
mount. Refer to Group 9 for procedure.
(9) Fill cooling system. SeeCooling System Fill-
ing.
(10) Install accessory drive belts, Refer to Acces-
sory Drive Belts, in this section.
(11) Lower vehicle and connect battery cable.
WATER PUMP INLET TUBEÐ2.4L ENGINE
REMOVAL
(1) Drain cooling system. Refer to procedure out-
lined in this section.
(2) Remove upper radiator hose to access the hose
connections at the inlet tube.
(3) Remove lower radiator hose and heater hose
from the inlet tube (Fig. 18).
(4) Remove the 2 fasteners that hold the inlet
tube to the block.
(5) Rotate tube while removing the tube from the
engine block (Fig. 19).
INSTALLATION
(1) Inspect the O-ring for damage before installing
the tube into the cylinder block (Fig. 19).
(2) Lube O-ring with coolant and install into the
cylinder block opening.
(3) Install 2 fasteners and tighten to 12 N´m (105
in. lbs.).
(4) Connect lower radiator hose and heater hose
to inlet tube (Fig. 18).
Fig. 16 Water PumpÐ2.4L Engine
Fig. 17 Water Pump Body
NSCOOLING SYSTEM 7 - 17
SERVICE PROCEDURES (Continued)