2008 GMC Acadia Owner's Manual - Page 344

{CAUTION: You can be burned if you spill coolant on hot engine parts. Coolant contains ethylene glycol and it will burn if the engine parts are hot enough. Do not spill coolant on a hot engine. When the coolant in the coolant recovery tank is at the FULL COLD mark, start your vehicle. If the overheat warning continues, there is one more thing you can try. You can add the proper mixture directly to the radiator, but be sure the cooling system is cool before you do it. 1. To remove the panel that covers the radiator cap, detach fasteners and lift off panel. 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. 5-30