Page 217 of 1938

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)
Page 218 of 1938

ties to keep the engine satisfactorily cooled (Fig. 5),
(Fig. 6), (Fig. 7) and (Fig. 8).
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.
RADIATOR PRESSURE CAP
The radiator is equipped with a pressure cap that
releases excessive cooling system pressure; maintain-
ing a range of 97-124 kPa (14-18 psi).
The cooling system will operate at higher than
atmospheric pressure. The higher pressure raises thecoolant boiling point thus, allowing increased radia-
tor cooling capacity.
There is also a vent valve in the center of the cap.
This valve also opens when coolant is cooling and
contracting allowing coolant to return to radiator
from coolant reserve system tank by vacuum through
connecting hose.If valve is stuck shut, or the
coolant recovery hose is pinched, the radiator
hoses will be collapsed on cool down. Clean the
vent valve (Fig. 9) and inspect coolant recovery
hose routing, to ensure proper sealing when
boiling point is reached.
The gasket in the cap seals the filler neck, so that
vacuum can be maintained, allowing coolant to be
drawn back into the radiator from the reserve tank.
Fig. 5 Cooling ModuleÐ2.4L
Fig. 6 Cooling ModuleÐTrailer Tow (With Rear A/C)
7 - 4 COOLING SYSTEMNS
GENERAL INFORMATION (Continued)
Page 219 of 1938
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)
Page 220 of 1938

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
Page 221 of 1938

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)
Page 222 of 1938
COOLING SYSTEM DIAGNOSIS
7 - 8 COOLING SYSTEMNS
DIAGNOSIS AND TESTING (Continued)
Page 223 of 1938
NSCOOLING SYSTEM 7 - 9
DIAGNOSIS AND TESTING (Continued)
Page 224 of 1938
7 - 10 COOLING SYSTEMNS
DIAGNOSIS AND TESTING (Continued)