I have a 2003 Jetta 2.0. I just replaced the thermostat and i believe i have all the air out of the system. Engines is running at 190 have a ton of heat, but the bottom radiator hose is still cold is this right? Now I'm thinking maybe the water pump after reading on line how crappy they are. I took it down the road for a 15 minute ride and it stays right at 190 doesn't overheat and has plenty of heat. Any easy was of telling if it is the water pump?