How to Bleed the Radiator for an E39


1. Park the car in a well-lit area on a flat surface. Bleed the system when the engine is cold. From inside the car, turn the ignition key to the 'On' position. Use the climate controls to set the interior heat to 90-degrees and turn the fan to the lowest setting.
2. Open the hood. Remove the cap on the radiator expansion tank. Unscrew and remove the bleeder screws on the thermostat cover and expansion tank with a screwdriver.
3. Pour coolant (50/50 BMW coolant and distilled water) into the expansion tank until the tank is full and coolant flows bleeder hole on the thermostat cover. Continue pouring coolant into the expansion tank until the coolant that is coming out of the bleeder hole does not have any air bubbles. Install the bleeder screw and tighten it until the bleeder is closed.
4. Fill the expansion tank again to the very top. Continue filling it until the coolant that is coming out of the expansion tank bleeder screw has does not have air bubbles. Make sure that the expansion tank is full to the top during this process. Install and tighten the bleeder screw. Check that the expansion tank is full. If it is not, fill it to the top and then install the cap.
5. Drive the BMW until it is up to temperature, which will around ten to 15 minutes. Rev the engine to higher RPMs as well once it is warmed up.
6. Park the car and turn off the engine. Let the engine cool down completely, which will take several hours. Check the level of coolant in the expansion tank. If the tank is empty repeat the bleeding process. If the tank is low, fill it to the top level indicated on the expansion tank. Check the coolant level after the next few times the car is driven to make sure it is still full.