How to Burp the Air Out of an Engine Cooling System

When you drain the coolant system, it introduces air into the radiator and the lines. Filling the system with antifreeze does not purge all of the air, leaving residual bubbles that can wreak havoc on your engine. Air pockets in the cooling system can cause inefficient cooling that may result in overheating and long-term damage to sensitive engine components. Purge the air from the system any time you drain coolant.

Instructions

1. Raise the hood. Make sure the engine has cooled completely. Remove the cap from the radiator.

2. Start the engine and let it run until it reaches the typical operating temperature. The normal operating temperature will vary from vehicle to vehicle.

3. Turn on the heater inside the car. Top off the coolant level in the radiator as needed, letting the heat run for two minutes. Turn off the heat and the engine.

4. Let the engine cool completely. Add coolant to the radiator, if needed to fill the radiator. Replace the radiator cap and close the hood.

References

• "Popular Mechanics Complete Car Care Manual"; Popular Mechanics ed.; 2008