well boys and girls had a real pain in the *** repair on a 2000 a6 2.7t 235000 miles. This thing would overheat and pump the resavouir dry. you could drive it all day just dont turn it off. changed waterpump second water pump thermostat, temp sensors and relays to second waterpump. your not going to believe the problem was in the resavoir. I changed the plastic junk and the problem was solved. i would have sworn it was the aftertun pump. i was wrong.