Originally Posted by jpsum
i don't know much about BMW as my 330 is my first. But on all other car I have owned, I always change the water pump and themostat when it's time to change the timing belt. Save a shit load on labor.
BMW's are notorious for their weak cooling systems. I've had to completely overhaul the cooling system on every BMW I've owned (1 E36 & 2 E39 540's) anywhere between 60k miles and 100k miles. Not sure why the E90 will be any different, but time will tell! As has already been stated, your BMW doesn't use a timing belt.