March 2006: I think I have same noise. Car is Jetta 2000 TDI. Also I have heard it from another TDI in a parking lot. So far unable to catch a recording. It sounds like (almost) a squeaky fan belt, but lower pitched tone. Lasts only 1 or 2 seconds. Don't know if there is such a component, but the schedule on which it occurs makes me think there ia a servo motor moving some air valve that may have to do with preheated intake air, so this is resetting the valve after the engine has cooled off from warmed up state. Does anyone know if there even is such a function?? My noise occurs just after the engine fires up.
Able Gorble, March 2006