Bad water pump?
Yesterday my '08 535 overheated (40k mi). First I noticed that there was no heat through air vents, then the radiator fan turned on very high, then the overheat.
I've read a bunch about replacing the thermostat and water pump together, but I'm just trying to diagnose whether the pump is bad and I need to spend the $400 on that part.
I initiated the water pump bleed procedure, and the pump turns on and circulates some coolant, but it sounds very weak to me.
Please take a listen/look at my video and let me know if you think if the pump is working properly.