2003 Chevrolet Tahoe Owner's Manual - Page 389

Adding only plain water to your cooling system can be dangerous. Plain water, or some other liquid such as alcohol, can boil before the proper coolant mixture will. Your vehicle's coolant warning system is set for the proper coolant mixture. With plain water or the wrong mixture, your engine could get too hot but you wouldn't get the overheat warning. Your engine could catch fire and you or others could be burned. Use a 50/50 mixture of clean, drinkable water and DEX COOL@coolant. You can be burned if you spill coolant on hot engine parts. Coolant contains ethylene glycol are hot and it will burn if the engine parts enough. Don't spill coolant on a hotengine. 1. Park the vehicle on a level surface. You can remove the coolant surge tank pressure cap when the cooling system, including the coolant surge tank pressure cap and upper radiator hose, is no longer hot. L Notice: In cold weather, water can freeze and crack the engine, radiator, heater core and other parts. Use the recommended coolant and the proper coolant mixture. 2. Turn the pressure cap slowly counterclockwise (left) about one full turn. if you hear a hiss, wait for that to stop. A hiss means there is still some pressure left. 3. Then keep turning the pressure cap slowly, and remove it. 5-36