DIFFUSER 4328134 - Caterpillar

Caterpillar Diesel Truck Engines can operate effectively in cold weather, however, engine operation in cold weather is dependent on the type of fuel used and how well the fuel moves through fuel related components. The purpose of this section is to explain some of the problems and steps that can be taken to minimize fuel problems during cold weather operation when the engine area is colder than 5°C (40°F).Fuel and the Effect from Cold Weather
The two types of diesel fuel available for your truck engine are typically grades No. 1 and No. 2. Although No. 2 diesel fuel is the most commonly used fuel, No. 1 diesel fuel or a blend of No. 1 and No. 2, is the fuel that is best suited for cold weather operation.During cold weather operation, it may be necessary for you to use No. 2 diesel fuel since quantities of No. 1 diesel fuel are limited and generally are only available during the winter months and in the colder climates.There are two major differences between No. 1 and No. 2 diesel fuel. No. 1 diesel fuel has a lower cloud point and a lower pour point.The cloud point is the temperature at which a cloud or haze of wax crystals will begin to form in the fuel and cause fuel filters to plug. The pour point is the temperature which diesel fuel will begin to thicken and be more resistant to flow through fuel pumps and lines.Be aware of these fuel values when purchasing your diesel fuel and anticipate the average outside (ambient) temperature for the area your engine will be operating. Engines fueled in one climate may not operate satisfactorily if moved to another because of problems that result from cold weather. The average No. 1 diesel fuel has a lower BTU (kJ) (heat content) rating per unit volume of fuel than the average No. 2 diesel fuel. When using No. 1 diesel fuel, you may notice a drop in power and fuel efficiency, but should not experience any other operating effects.Before troubleshooting for low power or poor performance in winter months, check the type of fuel being used.The use of starting aids, engine oil pan heaters, engine coolant heaters, fuel heaters and fuel line insulation also provide a means of minimizing starting and fuel problems in cold weather when No. 2 diesel fuel is used.Fuel Related Components in Cold Weather
3176 Fuel Cooling
Fuel cooled ECMThe 3176 electronic control module is fuel cooled. Fuel is routed from the tank, to a primary fuel filter, through the transfer pump, then through cored passages in the electronic control module housing, on to the secondary fuel filter, and finally to the injection pump.Inlet fuel temperature to the transfer pump must never exceed 149°F (65°C). Fuel temperatures in