2009 Ford F250 Owner's Manual - Page 382

Maintenance and Specifications • Refer to the chart on the coolant container to ensure the coolant concentration in your vehicle will provide adequate protection at the temperatures in which you drive. Vehicles driven year-round in non-extreme climates should use a 50/50 mixture of engine coolant and distilled water for optimum cooling system and engine protection. What you should know about fail-safe cooling (if equipped) If the engine coolant supply is depleted, this feature allows the vehicle to be driven temporarily before incremental component damage is incurred. The "fail-safe" distance depends on ambient temperatures, vehicle load and terrain. How fail-safe cooling works If the engine begins to overheat: • The engine coolant temperature gauge will move to the red (hot) area. • The message center will indicate the engine is overheating. • The indicator will illuminate. If the engine reaches a preset over-temperature condition, the engine will automatically switch to alternating cylinder operation. Each disabled cylinder acts as an air pump and cools the engine. When this occurs the vehicle will still operate. However: • The engine power will be limited. • The air conditioning system will be disabled. Continued operation will increase the engine temperature and the engine will completely shut down, causing steering and braking effort to increase. Once the engine temperature cools, the engine can be re-started. Take your vehicle to a service facility as soon as possible to minimize engine damage. 382 2009 F-250/350/450/550 (f23) Owners Guide, 3rd Printing USA (fus)