General Information

ACCESSORY DRIVE BELT/TENSION
The accessory drive components are operated by a single, crankshaft driven, serpentine drive belt. An automatic belt tensioner is used to maintain correct belt tension at all times.
Correct accessory drive belt tension is required to be sure of optimum performance of belt driven engine accessories. If specified tension is not maintained, belt slippage may cause; engine overheating, lack of power steering assist, loss of air conditioning capacity, reduced generator output rate and greatly reduced belt life.
It is not necessary to adjust belt tension on any engine. All engines are equipped with an automatic belt tensioner. The tensioner maintains correct belt tension at all times. Due to use of this belt tensioner, do not attempt to use a belt tension gauge on any engine.

COOLING SYSTEM
The cooling system regulates engine operating temperature. It allows the engine to reach normal operating temperature as quickly as possible. It also maintains normal operating temperature and prevents overheating.
The cooling system also provides a means of heating the passenger compartment and cooling the automatic transmission fluid (if equipped). The cooling system is pressurized and uses a centrifugal water pump to circulate coolant throughout the system.
An optional factory installed maximum duty cooling package is available on most models. This package will provide additional cooling capacity for vehicles used under extreme conditions such as trailer towing in high ambient temperatures.

COOLING SYSTEM COMPONENTS
The cooling system consists of:
^ A down-flow radiator
^ Thermal viscous fan drive
^ Fan shroud
^ Radiator pressure cap
^ Thermostat
^ Coolant reserve/overflow system
^ Transmission oil cooler (automatic transmission)
^ Coolant
^ Water pump (to circulate coolant)
^ Hoses and hose clamps

COOLING SYSTEM CIRCULATION

Cooling Systems Circulation-Typical:

Coolant flow circuits for the 3.9L (V-6), 5.2L (V-8) and 5.9L (V-8) engines with water cooled intake manifolds are shown.

COOLANT RECOVERT SYSTEM

Coolant Reserve/Overflow Tank-Typical:

The coolant reserve/overflow system works in conjunction with the radiator pressure cap. It utilizes thermal expansion and contraction of coolant to keep coolant free of trapped air. It provides a volume for expansion and contraction of coolant. It also provides a convenient and safe method for checking coolant level and adjusting level at atmospheric pressure. This is done without removing the radiator pressure cap. The system also provides some reserve coolant to the radiator to cover minor leaks and evaporation or boiling losses.
As the engine cools, a vacuum is formed in the cooling system of both the radiator and engine. Coolant will then be drawn from the coolant tank and returned to a proper level in the radiator.
Should the reserve/overflow tank become coated with corrosion or emulsified oil, it can be cleaned with detergent and water. Rinse tank thoroughly before refilling cooling system.

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 preventing leakage through them and to guarantee a minimum engine operating temperature of 88 to 93°C (192 to 199°F). 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 104°C (220°F). Above this temperature the coolant temperature is controlled by the fan, the radiator, and the ambient temperature, not the thermostat.

WATER PUMP
A quick test to determine if pump is working is to check if heater warms properly. A defective water pump will not be able to circulate heated coolant through the long heater hose to the heater core.
The water pump on all models can be removed without discharging the air conditioning system (if equipped).

WATER PUMP BYPASS HOSE

Water Pump Bypass Hose-Typical:

A water pump bypass hose is used between the intake manifold and water pump on all engines.

COOLANT
The cooling system is designed around the coolant. Coolant flows through the engine water jacket absorbing heat produced during engine operation. The coolant carries the heat to radiator and heater core. Here it is transferred to the ambient air passing through the radiator and heater core fins. The coolant also removes heat from the automatic transmission fluid in vehicles equipped with an automatic transmission.

WARNING: ANTIFREEZE IS AN ETHYLENE GLYCOL BASE COOLANT AND IS HARMFUL IF SWALLOWED OR INHALED. IF SWALLOWED, DRINK TWO GLASSES OF WATER AND INDUCE VOMITING. 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 RUNNING TEMPERATURE, PERSONAL INJURY CAN RESULT. AVOID RADIATOR COOLING FAN WHEN ENGINE COMPARTMENT RELATED SERVICE IS PERFORMED, PERSONAL INJURY CAN RESULT.

CAUTION: Do not use straight antifreeze as engine coolant, inadequate engine running temperatures can result. Do not operate vehicle without proper concentration of recommended ethylene glycol coolant, high running temperatures and cooling system corrosion can result.

The cooling system factory fill is a mixture of 50% Ethylene Glycol based antifreeze and 50% water. Using a suitable hydrometer, measure antifreeze concentration in the radiator when the engine is cool. If the cooling system has recently been serviced, allow coolant to circulate for at least 20 minutes before taking hydrometer reading. Properly mixed coolant will protect the cooling system to -37°C (-35°F). If the freeze protection is above -28°C (-20°F), drain enough coolant from the cooling system to allow room to add antifreeze to achieve adequate protection.
Chrysler Corporation recommends Mopar Antifreeze/Coolant or a high quality, ethylene glycol base antifreeze/coolant, with a silicate inhibitor

RADIATOR PRESSURE CAP
The radiator is equipped with a pressure cap that releases built up pressure, maintaining a range of 97-138 kPa (14-20 psi).
The cooling system will operate at higher than atmospheric pressure. The higher pressure raises the coolant boiling point, thus allowing increased radiator cooling capacity.

RADIATOR
The radiator is a down-flow type (vertical tubes). The radiator supplies sufficient heat transfer to cool the engine and automatic transmission (if equipped).

BLOCK HEATER
The engine block heater is available as an optional accessory for 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 engine coolant.