My 2002 Volkswagen GTI has been overheating. It almost hit 290 every time. But it only does that when im driving. Theres also steam coming from the bottom of the reserve. I notice my auxiliary pump is leaking pretty bad. I also noticed, when i used to turn the car off one of the fans would kick on. It stopped doing that. Could the auxiliary cause this? Im going to try to change the thermostat this weekend and see if thats the problem. Anybody know what might be causing this?