Hi, I have a strange and worrying situation...my 2001 Arosa Tdi has been into the garage twice now to investigate my water loss issue. There is a loss of coolant but no leaks - anywhere and the temp stays rock solid at 90. I have changed the expansion bottle and and cap - no effect. The garage added some dye to the coolant but they cant find any leaks... I have done an oil change and there is no mayo in the oil, its all clean. the only other symptom is an increase in fuel consupmtion - normally 350-370 per tank now its around 320. The garage thinks it could be HGF but without taking it all apart they cant say for sure... Does anyone have any other ideas? Change the temp sender/thermostat? How much should i budget for a HG change? Should i get the waterpump done as well as the cambelt? thanks!!