The dealer says the timing belt is weather cracked.
Should I have the timing belt replaced? on 1999 Audi A8
The timing belt is due by age. If it is the original timing belt, it is over 72 months old which is the time interval for the belt, before they crack. A timing belt has a rubber that cracks, much like tires. After about 72 months ( 6 years ) the rubber will crack or get 'age cracks'.
Not sure about the states, but in europe Audi recommends that you change the timing belt every 120,000 kilometers.