Principles of Operation

Powertrain Secondary Cooling System

Principles of Operation

Coolant flows primarily from the degas bottle to the coolant pump. From the coolant pump, coolant is sent through the radiator. From the radiator coolant is sent to the 4 components cooled by the system. Coolant flow to the transmission cooler and EGR cooler is controlled by the thermostat on the RH side of the radiator. Coolant flow to the Charge Air Cooler (CAC) and the fuel cooler is controlled by the thermostat on the LH side of the radiator. The coolant then returns to the degas bottle. The coolant pump is operated by engine rotation through a pulley which is driven by the accessory drive belt to circulate the coolant. The coolant thermostat is a control valve actuated by coolant temperature. When the thermostat is closed, coolant flow bypasses the radiator circuit. When the thermostat is opened, coolant is allowed to flow through the radiator circuit in order to transfer heat to the outside air.

The degas bottle holds surplus coolant and removes air from the cooling system. It also allows for coolant expansion and system pressurization, replenishes coolant to the cooling system and serves as the location for service fill.