VALVE GP-RELIEF 3100390 - Caterpillar

All Caterpillar Truck EnginesThe 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 poor 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 250 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