Replacing the engine coolant after a repair -- or as a part of the normal maintenance schedule -- in your 2000 Chevy Impala is slightly different than most other cars. The radiator and some of the coolant passages sit higher in the engine compartment than the coolant reservoir. As a result, air can become trapped in the engine block, causing severe overheating if the air isn't removed before driving the car. The average home mechanic can complete the coolant replacement procedure in about an hour.
Allow the engine to cool completely, and unscrew the pressure cap from the coolant reservoir located on the passenger side of the engine compartment. Position the floor jack under the front sub-frame, and raise the car up a few inches so you can work under the bumper area of the car. Place jack stands under the sides of the sub-frame, and lower the Impala onto them.
Remove the splash shield located under the radiator core support by twisting the thumb screws holding it in place counterclockwise until it comes off. Place a drain pan under the pet-cock valve located on the driver side lower corner of the radiator. Twist the thumbscrew on the pet-cock, and allow the coolant to drain into the drain pan.
Close the pet-cock when the radiator is drained, and slide the drain pan from under the car. Reinstall the splash shield. Raise the Impala off the jack stands, and remove the stands. Lower the Chevy to the ground, and roll the jack out from under the car.
Remove the air bleed screw from the coolant bypass tube located on the back of the water pump housing near the passenger side front of the engine. Pour a 50/50 mix of antifreeze and water into the coolant reservoir. As the coolant fills the reservoir, the engine and radiator air will be pushed out of the bleed screw opening. Continue to add coolant in this manner until coolant comes out of the bleed screw opening.
Reinstall the bleed screw, and start the engine. Allow the engine to run until the thermostat opens and the upper radiator hose, located on the driver side of the engine, becomes hot. The level will drop in the reservoir when this happens. Add coolant until the coolant level is at the hot/full mark on the side of the reservoir. Reinstall the pressure cap on the reservoir, and test drive the car.
