Winter Fronts

Winter fronts on Detroit™ Gen 5 Heavy Duty engines are seldom necessary due to the modern design of the engine cooling system. The coolant 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

The use of a winter front should be avoided as this has been shown to cause false fault codes and performance issues with the engine and aftertreatment system. Winter fronts can result in the following:

• Excessive fan run time due to higher Charge Air Cooler (CAC) outlet temperatures resulting from low air flow through the CAC.
• Increased fuel consumption.
• Failure of the DEF system heaters to turn on when needed due to incorrect temperature calculations. This results in fault codes, poor performance of the aftertreatment system, and power reduction.
• Failure of critical emission equipment that will result in vehicle speed inducement to a maximum of 5 mph.

There are two specific situations where a winter front may be temporarily needed:

• To improve cab heating while idling under extreme cold ambient temperature.
• When the ambient temperature remains below -30°C (-22°F) and the engine is unable to maintain running coolant temperature of 80°C (175°F) during normal over-the-road operation

If either of the above situations is encountered, a winter front may be temporarily used. A minimum of 25% of the grille must be open in sectioned stripes that run perpendicular to the charge air cooler tube flow direction. This assures even cooling across each tube and reduces header-to-tube stress and possible failure.