Cooling System: Operation

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 source of hot coolant for 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.

• When the engine is cold, the thermostat is closed. The cooling system has no flow through the radiator. The coolant flows through the engine, water pump, and heater.
• When the engine is warm, the thermostat is full open. On the gas and diesel engines coolant flows through the engine, radiator, heater, and water pump.

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.