2009 GMC Acadia Owner's Manual - Page 308

5-22 Service and Appearance Care CAUTION (Continued) 2. Remove the radiator pressure cap when the cooling system, including the upper radiator hose, is no longer hot. Turn the pressure cap slowly counterclockwise about one full turn. If you hear a hiss, wait for that to stop. A hiss means there is still some pressure left in the system. How to Add Coolant to the Radiator { CAUTION An electric engine cooling fan under the hood can start up even when the engine is not running and can cause injury. Keep hands, clothing, and tools away from any underhood electric fan. pressure cap, is hot. Wait for the cooling system and surge tank pressure cap to cool if you ever have to turn the pressure cap. If coolant is needed, add the proper mixture directly to the radiator, but be sure the cooling system is cool before this is done. { CAUTION Steam and scalding liquids from a hot cooling system can blow out and burn you badly. They are under pressure, and if you turn the surge tank pressure cap - even a little - they can come out at high speed. Never turn the cap when the cooling system, including the surge tank (Continued) 1. Detach fasteners and lift off the panel that covers the radiator cap. 3. Keep turning the pressure cap slowly and remove it. 4. Fill the radiator to the base of the filler neck with the proper DEX-COOL coolant mixture. 5. When coolant begins to flow out of the filler neck, reinstall the pressure cap. Be sure to secure it tightly.