2005 Buick LeSabre Owner's Manual - Page 271

How to Add Coolant to the Radiator 1. You can remove the radiator pressure cap when the cooling system, including the radiator pressure cap and upper radiator hose, is no longer hot. Turn the pressure cap slowly counterclockwise until it first stops. Do not press down while turning the pressure cap. If you hear a hiss, wait for that to stop. A hiss means there is still some pressure left. 2. Then keep turning the pressure cap, but now push down as you turn it. Remove the pressure cap. 3. Remove the 3800 Series II V6 engine cover shield to access the bleed valve. 3.1. Clean the area around the engine oil fill tube and cap before removing. Twist the oil fill tube, with cap attached, counterclockwise and remove it. 3.2. If you have the supercharged engine, remove the nut in the center of the cover shield. 3.3. Lift the engine cover shield at the front, slide the catch tab out of the engine bracket and remove the cover shield. 3.4. Put the oil fill tube, with cap attached, in the valve cover oil fill hole until you are ready to replace the cover shield. 5-31