Usage:
All Caterpillar Truck Engines
The following article will explain problems, and steps that can be taken to minimize the effects of cold weather on Caterpillar Truck Engines. Caterpillar Truck Engines can operate effectively in cold weather. If fuel line freezing is a persistent problem, use this article as a guideline to inspect your vehicle for problem areas. Contact your fuel supplier to obtain additional information for the climate your truck will operate in. Refer to Caterpillar Engine Data Sheet 60.1, Form LEKQ3363 for detailed information on fuels recommended for use in Caterpillar Truck Engines. For additional information on the effects of cold weather on your Caterpillar Truck Engine, see the Operation & Maintenance Guide, Form SEBU5898 "Cold Weather Recommendations".
FUEL
There are two grades of diesel fuel available in North America and Canada. The two grades are No. 1 and No. 2 with No. 2 being the most commonly used. No. 1 fuel is generally available only in winter months, and only in colder climates. There are two major differences between No. 1 and No. 2 diesel fuel. No. 1 fuel has a lower cloud point, and it has a lower pour point. The cloud point is the temperature point at which wax will begin to form in the fuel, and cause fuel filters to plug. The pour point is the temperature point at which diesel fuel will begin to thicken and be more resistant to flow through fuel pumps and lines. Customers and drivers should be aware of these fuel values when they purchase fuel and anticipate the average ambient temperature for the areas their trucks will be operating. If a truck is fueled in a warmer climate, then driven into a colder climate, fuel problems can occur if adequate precautions are not taken. In addition, No. 1 fuel has a lower BTU (heat content) rating per unit volume of fuel. Drivers who use No. 1 fuel may notice a drop in horsepower and fuel mileage, but should experience no other operating effects. Before troubleshooting for low horsepower or peer performance in winter months, check the type of fuel being used.
FUEL TANKS
Fuel tanks should contain some provision for draining water and sediment from the bottom of the tanks. Some fuel tanks use supply pipes that allow water and sediment to settle below the end of the fuel supply pipe. This water and sediment should be drained at least every six months. Some fuel tanks use supply lines that take fuel directly from the bottom of the tank. In these systems, regular maintenance of fuel filters and water separators is important.
The fuel return line from the engine should return fuel to the same tank from which it was taken. The fuel return line should deposit fuel within 25 mm (9.8 ") of the supply line. This allows the engine to get warm fuel from the tank. It also allows air to escape from the return fuel without being pulled back into the engine.
FUEL LINES
Fuel supply lines should be 9.53 mm (.375") to 12.70 mm (.500 ") in diameter. Use as few fittings and connections as possible. Avoid sharp angles in fuel lines. Moisture in the fuel will tend to collect and freeze at any point the fuel changes direction. Fuel should be drawn from the tank closest to the engine. Fuel lines should travel the most direct route to the engine compartment.
FUEL HEATERS
Use of a fuel heater can help eliminate some cold weather problems. A fuel heater should be installed so that the fuel is heated before it goes into the first or primary fuel filter. Select a fuel heater that is mechanically simple, yet adequate for the application. The fuel heater should also prevent overheating of the fuel. A loss of engine horsepower can occur if fuel supply temperature exceeds 52 °C (125°F). Heat type fuel heaters should have a bypass provision for warm weather operation. Further information on fuel heaters is available from your Caterpillar Dealer (refer to Caterpillar Engine Data Sheet 64.5, Form LEHQ0362).
FILTERS AND WATER SEPARATORS
The use of a primary fuel filter is recommended. The micron rating and location of a primary fuel filter is important in cold weather operation. The primary fuel filter and its fuel supply line are the most common components affected by cold fuel. The micron rating of the primary fuel filter should only be fine (low) enough to protect the fuel transfer pump. A very fine (low micron rating) primary filter, can be more easily plugged by wax in cold weather. A primary filter, with a micron rating as fine as a secondary filter (10-15) microns), can cause waxing problems in cold weather. An 8H7204 Filter is recommended as a cold weather primary fuel filter. The best location for the primary fuel filter is in the engine compartment, where it will benefit from the radiant heat of the engine. A filter mounted outside the frame rails, or any location exposed to wind, can be a persistent problem in cold weather.
Water separators can be used either separately or in combination with a primary fuel filter. Water separators are recommended on engines with scroll fuel systems and are mandatory on engines with sleeve metering fuel systems. Water separators must be drained regularly to prevent freezing. Therefore, they should be located in an easily accessible area to encourage frequent servicing.
MAINTAIN ENGINE COMPARTMENT TEMPERATURE
Radiator shutters and on/off fans are excellent devices for maintaining engine compartment temperatures. If the radiator shutter thermostat is located in the cylinder head or upper radiator hose, it should open the shutters at a temperature that is 5.6 °C (10°F) higher than the opening temperature of the engine thermostat. If the thermostat is located in the lower radiator hose, it should be set at the same temperature as the opening temperature of the engine thermostat.
On/off fan thermostats should open at a temperature that is 2.8 ° to 5.6°C(5° to 10°F) higher than the temperature setting of the shutters. The sequence of these events is important to maintain engine temperature and obtain optimum fuel economy.
ENGINE FUEL RETURN
It is a common belief that large amounts of warm engine return fuel in the fuel tanks can reduce cold weather problems. The benefit of the warm engine return fuel is affected by the temperature of the fuel and the amount of fuel in the tank with which it is mixed. It is important to remember that increasing the amount of return fuel increases the amount of fuel that must pass through the fuel filters. This increases the possibility of fuel filter waxing problems.