What are you doing in the timing case? Just curious
. How often should the timing chain be replaced, if ever?
If you keep the tensioner replaced every 40k, your chain may go 180k miles or more. I have heard of people selling ones with 140k on them and claiming they are fine. If you do not keep it fresh, your chain may last as little as 100k-120k miles as mine did.
Unfortunately little has come out of BMW regarding any of this, so those numbers are based on what I have seen on this board and others, as well as my own experience.