Flushing the Coolant System Draining Coolant On a cool engine (less than 140*F) remove the radiator cap. Now at the bottom of the radiator, there is a drain valve on the radiator. The drain turns 1/2 turn then pulls outward slightly then continues to turn to drain. To drain the overflow bottom it just easier to remove the hose from the radiator neck and then pull the overflow bottle upwards from the fan shroud. Flushing Cooling System Flushing the cooling system you'll need t