Recently bought myself a 05 Astra 1.9 CDTI with 85k on the clock and have noticed a weird noise when it's ticking over. It's hard to describe the noise, but best description is "choo...choo...choo...choo" and is in time with the cambelt/engine. Guessing it's something to do with the cambelt, but doesn't sound like a rubbing kind of noise.
Also, hasn't had the cambelt changed yet, so guessing it will need doing very soon...if not now!
Hope someone can help or have had the same problem with theirs....might even be the norm for all I know!