Cooling System: Description and Operation

Coolant Flow 3.9L








Coolant Flow 3.0L

The cooling system components include the:
^ block heater (optional)
^ cylinder head temperature sensor
^ fan blade, fan motor and fan shroud assembly
^ radiator
^ pressure relief cap
^ degas bottle
^ radiator draincock
^ water pump
^ oil cooler (optional)
^ water thermostat

The water thermostat:
^ controls the engine coolant temperature.
^ allows quicker engine warm-up.

The degas bottle:
^ provides a location for system fill.
^ contains coolant expansion and system pressurization.
^ provides air separation during operation.
^ replenishes the engine coolant to the system.
The fan blade draws air through the radiator to help cool the engine coolant.

The fan motor:
^ operates only when the engine is running.
^ will not operate when the engine is off.

The engine coolant flows:
^ from the lower radiator hose to the water pump.
^ from the water pump to the engine block and the cylinder heads.

A closed water thermostat returns the engine coolant to the water pump. An open water thermostat allows the engine coolant to flow to the radiator.

Unsatisfactory coolant materials:
^ Alcohol-type antifreeze does not provide adequate water pump lubrication.
- has lower boiling point
- reduced antifreeze protection

^ Alkaline brine solutions will cause serious engine cooling system damage.

The cylinder head temperature sensor provides a signal to the temperature gauge.
^ will invoke fail-safe cooling.

The optional block heater:
^ electrical heating element is installed in the block cooling jacket. uses a standard 110 V (220 V in Europe) electrical supply
^ keeps the engine coolant warm during cold weather.

The auxiliary water pump (3.9L only):
^ provides heater coolant flow boost.
^ has a secondary function of providing engine-off cooling.