2004 Dodge Ram 3500 Pickup Owner Manual Diesel - Page 216

216 STARTING AND OPERATING Engine Speed Control CAUTION! Prevent overspeeding the engine going down hill. When descending steep grades, use a combination of gears and service brakes to control vehicle/engine speed. Overspeed can cause severe engine damage. Operating Precautions Avoid Overheating The Engine The temperature of the coolant (a mixture of 50% ethylene-glycol and 50% water) must not exceed the normal range of the temperature gauge (240°F/116°C) with a 16 psi (110 kPa) radiator cap. Usually the coolant temperature indicated during operation will be to the left of center in the normal range of the gauge. Avoid Low Coolant Temperature Operation Continual operation at low coolant temperature below the normal range on the gauge (140°F/60°C) can be harmful to the engine. Low coolant temperature can cause incomplete combustion which allows carbon and varnish to form on piston rings and injector nozzles. Also, the unburned fuel can enter the crankcase, diluting the lubricating oil and causing rapid wear to the engine. Cooling System Tips - Automatic Transmission To reduce potential for engine and transmission overheating in high ambient temperature conditions, take the following actions: • City Driving - when stopped, put transmission in neutral and increase engine idle speed. NOTE: The engine speed will automatically increase to 1000 RPM at elevated coolant temperature to improve engine cooling.