In the status bar above where the posts go, there is a link for "search." This is how you search the archives...

Do a search for "water pump," "M103 water pump" and "M104 water pump" and you should get some results that will be helpful. (Your car has the M104 engine, but I know there are a lot of posts on the M103, since I had to do one of those last year, and there may be some similarities between the two procedures.)