Different cars have different methods of purging air that is trapped in the cooling system. Every car manufacturer has guide on how to bleed a particular car. The manufacturer advice is to be followed.
However, through experience, there is a quick and easy way to do it especially when a non-technical person is in a situation where he or she cannot successfully locate bleed screws to perform the bleeding.
The person might not even have any tool to use. This method is as easy as ABCD... and it is actually a manufacturer recommended bleeding procedure of some cars.
Items needed for the cooling system bleeding
All that you need to purge air out of the cooling system is the new coolant. That's all! Having a funnel that can fit tightly to the expansion tank (where the cover normally fits into) may give added advantage.
Quick cooling system air purging procedure
Below are the steps to follow:
1. Allow the engine to cool.
2. While the engine is still off, remove the expansion tank cover or radiator cover of the cooling system.
3. Pour in fresh coolant until the cooling system is filled. If you have a funnel that fits tightly, use it to introduce the fluid. It helps to purge air out easily by raising the highest point of the cooling system. Another trick people use is raising the front end of the vehicle or by placing it on an incline.
4. Put transmission in park, activate the parking brake and start the engine (you might need someone else to do this for you).
5. Revv the engine to 3,000 revolutions per minute repeatedly but sometimes holding it steady at same rpm for few seconds.
6. When you are satisfied that all air has been purged out and before the coolant starts to boil or overflow, cover the radiator or expansion tank.
It is as easy as that. Air is purged out without a single tool! This might not work for every car on the planet but believe it, this works for many. Never let air in cooling system get you stranded anymore!
Caution: The level of coolant in an expansion tank should not be above the maximum level mark on the tank else there won't be room for coolant to expand and it will cause overheating.
Beware of a hot engine, hot coolant and moving engine parts like drive belts and pulleys when working on an engine.