I have an over heating issue on my Touareg. I've changed the thermostat and checked the water pump for proper operation and everything is fine there. I can hear bubbling coming from the coolant fill tank and the hose leaving the coolant tank is getting super hot and have the suspicion the auxiliary water pump failed or the heater core is clogged. I have been trying to find a diagram or info about someone else having this issue. I can't figure out where the line from the coolant tank goes on the back side of the engine. Does anyone have info?