After repairs on a cooling system are performed it is critical to remove all the air from the cooling system. I have personally used and own the AirLift cooling system vacuum bleeder. Click HERE to purchase this great tool!
After any repair on your vehicle's cooling system you will need to remove the air from the system to prevent engine damage. Air pockets left in the system are the most common cause of an engine overheat. Damage to an engine can occur quickly when going above the specified temperature.
Different manufacturers have different bleeding methods. Some utilize a bleeder "screw" like on a BMW E46 3 Series. In this case the bleed screw is removed and the system is filled until coolant overflows from the bleed screw hole. This does a good job of removing most of the air however, air pockets can still remain. Some manufactures you have to wait for the thermostat to open and be ready to add coolant with the reservoir cap or radiator cap off when the system "burps."
BMW recommends the use of a cooling system bleeder to remove as much air as possible from the cooling system after repairs. This tool is even more critical on the BMW N20 and N26 engine 4 cylinder engine. As well as the N63 and N63T 8 cylinder engine.
This tool will draw a vacuum on the cooling system and helps reduce the chance of a vehicle over heat after repairs are made.
This tool does require the use of a compressor.
For and all in one pressure tester and vacuum bleeder this is a great option as well!