this is a qoute from rec vw info thing
http://www.endosquid.com/audi/audinfo_vwFAQ.htmloads of info on mechanical and electrical problems
How often should I change my drive belt?
A: 8 Valve engines, around 60-75k miles, 16V's BEFORE you reach 50k miles. 8V
? engines will NOT be damaged if the thing breaks, 16V will be.
? The VR6 engines use an actual chain rather than a synthetic belt and do not
? have to be changed.
? The only exception to the 8V rule is the Heron head used on European
? A1 GTIs (not sold in the USA/Canada). It does interfere.
? Note that tensioning the belt correctly is tricky, if it's too tight you
? may prematurely wear out a bunch of bearings.
? If it's on too tight, you'll hear a characteristic whining/high pitched
? sound.
?