
(13) Raise the vehicle. Install the lower auxiliary
transmission cooler lines to the retaining clips on the
fan module shroud, if equipped.
(14) Install outlet hose retainer clip to the shroud.
Install the radiator outlet hose to the retaining clip.
(15) Lower the vehicle.
ENGINE BLOCK HEATER
REMOVAL
(1) Drain coolant from radiator and cylinder block.
Refer to Cooling System Drain, Clean, Flush and
Refill of this section for procedure.
(2) Remove power cord plug from heater.
(3) Loosen screw in center of heater. Remove
heater assembly.
INSTALLATION
(1) Thoroughly clean 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) Fill cooling system with coolant to the proper
level, vent air, and inspect for leaks. Pressurize sys-
tem with Radiator Pressure Tool before looking for
leaks.
(5) Install power cord plug to heater.
ACCESSORY DRIVE BELTSÐ2.4L
REMOVAL/INSTALLATION-ADJUST
GENERATOR AND AIR CONDITIONING
(1) Loosen lower generator pivot bolt and upper
locking nut, then loosen adjusting bolt (Fig. 32) to
remove belt tension.
CAUTION: Belt damage may occur if the following
procedure is not performed.
(2) Tighten lock nut to 21 N´m (180 in. lbs.) and
torque generator pivot bolt to 54 N´m (40 ft. lbs.). To
assure proper alignment of generator assembly.
Adjust belt tension by tightening the adjusting bolt
until proper belt tension is obtained. Refer to tension
specification in Belt Tension Chart.
(3) Torque lock nut to 54 N´m (40 ft. lbs.).
POWER STEERING PUMP
(1) From on top of the vehicle loosen locking nuts
D and F (Fig. 33).
(2) From under the vehicle loosen the pivot bolt E.
Loosen adjusting bolt G until belt can be removed.
(3) After installing a new belt, adjust belt tension
by tightening the adjusting bolt until the proper ten-sion obtained. Refer to tension specification in Belt
Tension Chart.
(4) Tighten locking nuts D and F to 54 N´m (40 ft.
lbs.).
(5) Tighten pivot bolt E to 54 N´m (40 ft. lbs.)
Fig. 32 Air Conditioning Compressor/Generator
BeltsÐ2.4L
Fig. 33 Power Steering Pump Adjustment
NSCOOLING SYSTEM 7 - 23
REMOVAL AND INSTALLATION (Continued)

ACCESSORY DRIVE BELTSÐ3.0L
GENERATOR/POWER STEERING PUMP BELT
REMOVAL/INSTALLATION
The Poly-V generator/power steering pump belt is
provided with a dynamic tensioner (Fig. 34) to main-
tain proper belt tension. To remove or install this
belt, apply force in a clockwise direction to the ten-
sioner pulley bolt (Fig. 34).
AIR CONDITIONING BELT
REMOVAL
To remove the air conditioning compressor drive
belt, first loosen the idler pulley lock nut, then turn
the adjusting screw to lower the idler pulley (Fig.
35).
INSTALLATION/ADJUSTMENT
To adjust the air conditioning drive belt,
loosen the idler pulley lock nut (Fig. 35) and adjust
belt tension by tightening adjusting screw. Refer toProper Belt Tension and Belt Tension Chart in this
Section for procedure. Tighten pulley lock nut to 54
N´m (40 ft. lbs.) after adjustment.
ACCESSORY DRIVE BELTÐ3.3/3.8L
REMOVE/INSTALL
GENERATOR, POWER STEERING PUMP, AIR CONDITIONING
COMPRESSOR AND WATER PUMP DRIVE BELT
The Poly-V Drive belt is provided with a dynamic
tensioner (Fig. 36) to maintain proper belt tension.
To remove or install this belt.
(1) Raise vehicle on hoist.
(2) Remove right front splash shield.
(3) Release tension by rotating the tensioner
clockwise (Fig. 36).
(4) Reverse above procedure to install.
CLEANING AND INSPECTION
WATER PUMP
Replace the water pump if it has any of the follow-
ing defects.
(1) Damage or cracks on the pump body.
(2) Coolant leaks; if the seal is leaking, this will be
evident by traces of thick deposits of greenish-brown
dried glycol running down the pump body and com-
ponents below. A thin black stain below pump weep
hole is considered normal operation.
(3) Impeller rubs inside of chain case cover
3.3/3.8L or cylinder block 2.4L engines.
(4) Excessively loose or rough turning bearing.
Fig. 34 Release Belt TensionerÐ3.0L
Fig. 35 Air Conditioning Drive BeltÐ3.0L Engine
Fig. 36 Accessory Drive BeltÐ3.3/3.8L Engines
7 - 24 COOLING SYSTEMNS
REMOVAL AND INSTALLATION (Continued)

ties to keep the engine satisfactorily cooled (Fig. 5)
and (Fig. 6).
CAUTION: Plastic tanks, while stronger then brass
are subject to damage by impact, such as wrenches
etc., or by excessive torque on hose clamps.
If the plastic tank is damaged, replace the radia-
tor.
DESCRIPTION AND OPERATION
WATER PUMP
2.0L GASOLINE
The water has a diecast aluminum body and hous-
ing with a stamped steel impeller. The water pumpbolts directly to the block (Fig. 7). Cylinder block to
water pump sealing is provided by a rubber O-ring.
The water pump is driven by the timing belt. Refer
to Group 9, Engine section for component removal to
access the water pump.
NOTE: The water pump on all models can be
replaced without discharging the air conditioning
system.
2.5L VM DIESEL
The Diesel engine water pump has an aluminum
body and housing with a stamped steel impeller. The
pump uses an O-ring gasket between body and hous-
ing. The water pump is driven by the accessory drive
belt, and the pump housing is bolted to the cylinder
block (Fig. 9).
NOTE: The water pump on all models can be
replaced without discharging the air conditioning
system.
Fig. 4 Low Coolant Level Sensor
Fig. 5 Cooling Module Ð2.0LGasoline
Fig. 6 Cooling Module ÐVM Diesel
NS/GSCOOLING SYSTEM 7 - 3
GENERAL INFORMATION (Continued)

THERMOSTAT OPERATION
2.5 VM DIESEL
The engine cooling thermostats are 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 (Fig. 10). The
thermostat has a hole to bleed off air in the cooling
system during engine warm up. The thermostat
begins to open at 80É C62É (176É F64É).
PRESSURE/VENT CAP
WARNING: Engine coolant can reach temperatures
of 200É fahrenheit or greater. If the cooling system
is opened with coolant at a high temperature, hot
coolant can be forced out of the system under high
pressures, causing personal injury. Allow system to
cool down prior to removing the pressure cap.
The pressure/vent cap is secured to the coolant
tank neck by a means of a cam lock system. This cap
releases excess pressure at some point within a
range of 90-117 kPa (13- 17 psi) for gasoline engines,
and 110±124 kPa (16±18 psi) for diesel engines. The
actual pressure relief point (in pounds) is labeled on
top of the cap (Fig. 11).
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 (Fig. 11) contains a
spring-loaded pressure relief valve. This valve opens
when system pressure reaches approximately 103
kPa (15 psi).
When the engine is cooling down, vacuum is
formed within the cooling system. To prevent collapse
of the radiator and coolant hoses from this vacuum, a
vacuum valve is used within the cap. This valve pre-
vents excessive pressure differences from occurring
between the closed cooling system and the atmo-
sphere. If the vacuum valve is stuck shut, the radia-
tor and/or cooling system hoses will collapse on cool-
down.
Fig. 7 Water PumpÐ2.0L Gasoline Engine
Fig. 8 Water PumpÐ2.0L Gasoline Engine
Fig. 9 Water PumpÐ2.5L VM Diesel
Fig. 10 Thermostat and Housing Ð 2.5L VM Diesel
7 - 4 COOLING SYSTEMNS/GS
DESCRIPTION AND OPERATION (Continued)

Initial belt adjustment is done with a adjustable
tensioner pulley. After the initial adjustment is per-
formed, an automatic belt tensioner is used to main-
tain correct belt tension at all times. Do not attempt
to check belt tension with a belt tension gauge on
vehicles equipped with an automatic belt tensioner.
Refer to Automatic Belt Tensioner in this group.
AUTOMATIC BELT TENSIONER
Drive belt tension is controlled by a spring loaded
automatic belt tensioner located below and to the
front of the engine oil filter (Fig. 12). This tensioner
is connected to a pivot bracket and a pulley (Fig. 12).
The pivot bracket rotates on a pivot pin attached to
the engine. Special machined washers with rubber
o-rings (Fig. 12) are used at each side of the pivot
bracket to help keep dirt and water away from the
pivot pin.
If a defective belt tensioner is suspected, a check of
this pivot bracket and pivot pin should be made. Cor-
rosion may have formed at the pin and may cause
the pivot bracket to stick. Belt slippage will result.
WARNING: BECAUSE OF HIGH SPRING PRES-
SURE, DO NOT ATTEMPT TO DISASSEMBLE THE
AUTOMATIC BELT TENSIONER. UNIT IS SERVICED
AS AN ASSEMBLY.
THERMOSTAT
DIAGNOSIS
Diesel engines, due to their inherent efficiency are
slower to warm up than gasoline powered engines,
and will operate at lower temperatures when the
vehicle is unloaded. Because of this, lower tempera-
ture gauge readings for diesel versus gasoline
engines may, at times be normal.
Typically, complaints of low engine coolant temper-
ature are observed as low heater output when com-
bined with cool or cold outside temperatures.
To help promote faster engine warm-up, an electric
engine block heater must be used with cool or cold
outside temperatures. This will help keep the engine
coolant warm when the vehicle is parked. Use the
block heater if the outside temperature is below 4ÉC
(40ÉF).Do not use the block heater if the out-
side temperature is above 4ÉC (40ÉF).
TESTING
NOTE: The DRB scan tool shoud be used to moni-
tor engine coolant temperature on the diesel
engine. Refer to the 1998 GS Powertrain Diagnostic
Manual for thermostat diagnosis procedure.
Fig. 12 Automatic Belt Tensioner Assembly
7 - 6 COOLING SYSTEMNS/GS
DESCRIPTION AND OPERATION (Continued)

(3) Remove power steering pump bracket bolts and
set pump and bracket assembly aside. Power steering
lines do not need to be disconnected.
(4) Remove timing belt.
(5) Remove inner timing belt cover.
(6) Remove water pump attaching screws to engine
(Fig. 15).
INSTALLATION
(1) Install new O-ring gasket in water pump body
O-ring groove (Fig. 16). Use small dabs of Mopar Sil-
icone Rubber Adhesive Sealant around the water
pump body to secure O-ring in place during installa-
tion.
CAUTION: Make sure O-ring gasket 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.). 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 inner timing belt cover.
(5) Install timing belt.
(6) Fill cooling system. SeeFilling Cooling Sys-
tem.
(7) Install power steering pump and accessory
drive belts.
WATER PUMP Ð 2.5L VM DIESEL
REMOVAL
(1) Drain cooling system. Refer to Draining Cool-
ing System in this Group.
(2) Remove the right inner splash shield (Fig. 17).
(3) Loosen the water pump pulley attaching bolts
(Fig. 18) before the accessory drive belt is removed.
(4) Loosen water pump accessory drive belts (Fig.
19). Remove water pump pulley.(5) Remove water pump attaching bolts and
remove pump.
INSTALLATION
(1) Install a new water pump to housing O-ring
gasket. Install pump and tighten the attaching bolts
to 22.6 N´m (205 in. lbs.)
Fig. 15 Water Pump Ð 2.0L Gasoline
Fig. 16 Water Pump Body Ð 2.0L Gasoline
Fig. 17 Right Side Splash Shield
Fig. 18 Water Pump and Pulley Ð 2.5 L VM Diesel
7 - 8 COOLING SYSTEMNS/GS
REMOVAL AND INSTALLATION (Continued)

INSTALLATION
(1) Install fan module on radiator.
(2) Install radiator.
(3) Tighten receiver/dryer lower bolt.
(4) Install radiator attaching bolts.
(5) Install lower and upper radiator hoses.
(6) Connect fan module.
(7) Install air cleaner housing and intake hose.
(8) Install radiator closure panel crossmember.
(9) Install power steering reservoir attaching bolts.
(10) Refill cooling system. Refer to Refilling cooling
system in this section for procedure.
(11) Connect battery.
WATER PUMP BELT Ð 2.5L VM DIESEL
REMOVAL
(1) Remove generator/power steering belt. Refer to
procedure in this section.
(2) Raise vehicle on hoist.
(3) Remove right side splash shield (Fig. 22).
(4) Loosen belt tensioner bracket bolts (Fig. 23).(5) Loosen adjuster lock nut.
(6) Loosen adjusting bolt, and remove belt.
INSTALLATION
(1) Install water pump belt.
(2) Turn adjusting bolt clockwise to tighten belt.
(3) Tighten lock nut.
(4) Tighten belt tensioner bracket bolts
(5) Lower vehicle.
(6) Install generator/power steering belt. Refer to
procedure in this section.
GENERATOR/POWER STEERING BELT Ð 2.5L VM
DIESEL
REMOVAL
(1) Loosen generator pivot bolt (Fig. 24).
(2) Loosen adjusting bracket bolt.
(3) Loosen adjusting nut.
(4) Remove generator/power steering belt.
INSTALLATION
(1) Install generator/power steering belt.
(2) Tighten adjusting nut.
(3) Tighten adjusting bracket bolt.
(4) Tighten generator pivot bolt.
CLEANING AND INSPECTION
WATER PUMP
Replace the water pump if it has any of the follow-
ing defects.
(1) Damage or cracks on the pump body.
Fig. 21 Radiator Closure Panel Crossmember
Fig. 22 Right Side Splash Shield
Fig. 23 Water Pump Belt Removal Ð 2.5L VM Diesel
7 - 10 COOLING SYSTEMNS/GS
REMOVAL AND INSTALLATION (Continued)

(2) Coolant leaks; if the seal is leaking, this will be
evident by traces of thick deposits of greenish-brown
dried glycol running down the pump body and com-
ponents below. A thin black stain below pump weep
hole is considered normal operation.
(3) Impeller rubs inside of the cylinder block 2.0L
engine. Impeller rubs inside of the water pump hous-
ing 2.5L VM diesel engine.
(4) Excessively loose or rough turning bearing.
NOTE: It is normal for the water pump to weep a
small amount of coolant from the weep hole (black
stain on water pump body). Do not replace the
water pump if this condition exists. Replace the
water pump if a heavy deposit or a steady flow of
green/brown engine coolant is evident on water
pump body from the weep hole (shaft seal failure).
Be sure to perform a thorough analysis before
replacing water pump.
ADJUSTMENTS
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. For 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 the belt tension for aNeworUsedbelt as
prescribed in the Belt Tension Chart.
BELT TENSION CHART
Fig. 24 Generator/Power Steering Removal ± 2.5L
VM Diesel
ACCESSORY DRIVE
BELTGAUGE
2.0L GASOLINE ENGINE
GENERATOR AND AIR
CONDITIONINGNEW 667644 N (150
610 LBS).
USED 556 N (125 LBS.)
POWER STEERING NEW 578644 N (130
610 LBS).
USED 489 N (110 LBS).
2.5L VM DIESEL
WATER PUMP NEW N/A LBS.
USED N/A LBS.
GENERATOR /AIR
CONDITIONING/
POWER STEERINGNEW 667644 N (150
610 LBS).
USED 556 N (125 LBS).
NS/GSCOOLING SYSTEM 7 - 11
CLEANING AND INSPECTION (Continued)