[segfault]

This procedure comes from SIB 120405, and indicates that the cooling system needs to be bled after replacing the electric cooling pump. This is probably something that should be done whenever you suspect that air has gotten into the cooling system. In my experience, air in the coolant can cause poor engine cooling, poor heater performance, and "waterfall" noises underneath the dash. Note also that the coolant in E90s is considered lifetime coolant that does not normally require replacement unless repairs are done to the cooling system.

Bleeding (venting) cooling system
Note: Always connect a battery charger while performing the bleeding process.
1. Fill system with coolant via the expansion tank (AGB). Top up coolant level to lower edge of expansion tank.
2. Close expansion tank.
3. Switch on ignition. (Note by segfault: they mean switch it on without starting the car--press the start button until the dashboard malfunction lights come on.)
4. Set heating to maximum (temperature); switch on blower (lowest stage).
5. Press accelerator pedal module to floor for at least 10 seconds. The engine must NOT be started.
6. Bleeding via EWP takes approximately 12 minutes. Then check the cooland level in expansion tank, top up to MAX marking if necessary.
7. Check cooling circuit and drain plugs for leaks.
8. If the procedure needs to be repeated several times, allow DME to completely de-energize (remove ignition key for app. 3 minutes) and then repeat procedure as from item 3.