How to Bleed a Radiator on a 2003 BMW 325i

1. Park your car on level ground and allow its engine to cool for at least three to five hours.
2. Jack the car up and place it on axle stands.
3. Disconnect the negative cable from the battery.
4. Remove the cap from the top of the radiator.
5. Place the drain pan underneath the blue plastic drain plug, found at the bottom of the radiator. Remove the plug with a wrench or spanner.
6. Drain the fluid until it stops. If it contains any debris or metal flakes, you will need a professional to inspect your radiator.
7. Drain the coolant into a bottle, seal it, and dispose of it at an appropriate recycling facility.
8. Inspect the radiator cap for dry rot or wear and tear. Replace it with a new cap if necessary.
9. Flush cold water through the radiator.
10. Fill the radiator with water to help remove the remaining antifreeze.
11. Replace the radiator cap and turn on the engine for five minutes.
12. Turn off the engine and allow it to cool.
13. Repeat steps 3 to 6 until the water is clear.
14. Pour the flushing agent into your radiator. Repeat steps 11 and 12, and then drain the flushing agent.
15. Replace the plug once all of the coolant is emptied out of the radiator. Tighten to 2 to 3 Nm (18 to 27 inch pounds).
16. Remove the small plastic bleed screw to the right of the radiator cap. Using a large funnel in the expansion tank, slowly fill the car with new liquid--50 percent coolant, 50 percent distilled water. Restart the car engine for five minutes to open the thermostat.
17. Add more antifreeze or coolant until the radiator is full. Screw the cap back on the radiator.
18. Bleed the air out of the expansion tank on the side of the radiator. Otherwise you will have a separate, external expansion tank which is self-bleeding. With the bleed screw removed, fill the expansion tank until fluid begins coming out of the bleed screw.
19. Run the engine until it reaches its operating temperature. Turn off the engine and let it cool down. Top up the coolant in the expansion tank to the appropriate level, if necessary.