Expension Tank and Aux sensor go with BMW only! Behr is oem but make their oem parts in China... had both in position and although they looked identical, their colors differed slightly. the sensor is about $20 at bmw so no point in cutting corner there... water pump oem is saleri ... will last you another 200k no problem...
also you don't need to drain from the block, not really necessary because 90% of the coolant will come out from the bottom hose.
One thing is make sure you have the bottom drain plug oring as the old will leak once you put it back. and as stated... do the pulleys and hoses as well.
The cooling system is one of those hit or miss items... some guys experience failure at 160k and some drive to 250 on original components... best is to change it at around 200k if you plan on keeping it for another 50k+
Last edited by pawelgawel; 01-19-2013 at 05:12 PM.