A Diesel cold weather package is used. This package consists of an in-line diesel fuel heater and the engine block heater. (Figure 4-14).
The purpose of the heater is to heat the fuel so that the filter does not plug with paraffin wax crystals. This allows the use of more efficient #2 Diesel fuel at temperatures substantially below its cloud point.
The heater is electrically powered from the ignition circuit and is placed on the fuel filter inlet line a short distance up stream from the filter. Following are some of the qualities designed into this system:
The heater is in-line, and in fact, a component of fuel pipe assembly between fuel lift pump and filter. It does not have any additional seals or joints that increase the possibility of fuel leaks.
The heater is thermostatically controlled to work when waxing of the fuel is expected. Thermal feedback from the heating element to the bimetal actuator protects the element from burning out if for any reason fuel is not flowing through the fuel heater.
OPERATION
The device can be divided into two major functional components, the heater and the power control assemblies. (Figure 4-15).
The heater is 7/8 inches in diameter and approximately 51/2 inches long and consists of an electric resistance strip spiral wound and bonded around the fuel pipe. To minimize the heat loss to the environment, heating element is surrounded by an insulating fiber.
The power control assembly senses fuel temperature and responds by closing an electrical circuit to the heater. The sensing element is a bimetal switch. The internal bimetal switch turns on at 20 degrees F. and shuts off at 50 degrees F. Power consumption is 100 watts. The heat will only be on until the under hood temperature gets hot enough to warm the fuel.
The fuel tank filter sock has a bypass valve which opens when the filter is covered with wax allowing fuel to flow to the heater. Without this bypass valve fuel line heater would be ineffective because the fuel would be trapped in the tank. Since the bypass valve is located at the upper end of the sock, fuel will only be drawn into the waxed sock if the tank contains more than approximately 4 gallons of fuel. Therefore it is important to maintain a minimum level of 1/4 tank of fuel when temperatures are below 20°F.
