Hi all. I've been trying to trouble shoot an overheating issue using this forum. My 2011 2L TDI is periodically spitting the coolant out. I have read the thread on the heater coil problem and have checked for blockages there. Still no heat on the dash. I've had a new thermostat put in and the pressure test came back fine as well as the tk test. Obviously could be a head gasket but I'm not convinced yet. What I am wondering is the auxiliary water pump that is in line with the heater coil. When should it be running? It's not running with the heat on inside the car and only ever seems to run occasionally when I switch the car off.