Chances are it is water pump. Water pumps start leaking quite often when
they are not replaced together with timing belt and the belt's tension is
not adjusted absolutely perfectly.

Check out this message, sounds exactly like your case:
http://forums.audiworld.com/a6/msgs/40607.phtml

Good luck



"Pronto Breakneck" <no_address@example.com> wrote in message
news:9nkfiv83l6gpiqi5muf44s8t6p2fft4l0j@4ax.com...
> I changed the timing belt in our 1997 A4 a few months ago, and the car
> seems to have developed a slow coolant leak. It's only losing about
> half a cup or so a month, but it's frustrating nonetheless.
>
> As I like to live dangerously, I didn't change the water pump while I
> was in there. I didn't open the cooling system at all, so I'm a
> little confused as to why this is cropping up. I suspect I loosened a
> hose when I moved the front end carrier forward, but I can't find the
> leak for the life of me.
>
> Does anyone have any insight or hints on where to look first?
>
> thanks!
>
>