Cooling System

A radiator/thermo-modulated fan cooling system is used on Detroit™ Gen 5 Heavy Duty engines. This system uses a water pump to circulate coolant within the engine. The thermostat controls the flow of coolant. The thermostat is mounted on the inlet side of the cooling system and regulates coolant flow from the radiator into the engine. The thermostat regulates coolant flow to control the temperature of the coolant within the coolant circuit. The following benefits are a result from regulating the coolant at the inlet temperature side of the engine:

• Reduced thermal cycling of the engine

• Operating temperature is reached faster

• Improved vehicle heating because of better temperature regulation

Always use coolants that meet Detroit™ specifications . Failure to maintain the cooling system at required concentrations or using coolants that do not meet Detroit™ specifications will result in premature wear or engine failure . For a listing of required cooling system service intervals, Preventive Maintenance Tables. The "How to Procedures" section of this manual contains additional information on "How to Select Coolants".