Hi Guys Audi A4 B6 1.9 TDI 130, AVF, 2004 I've noticed coolant is leaking from the hole under the coolant tank, when ive been driving, it isnt loosing much at the moment, but when I open the bottle pressure comes out and the coolant rises. Ive have replaced the coolant tank with a new one, still leaking. I've also replaced the thermostat (genuine), temp sensor, because it wasnt sitting at 90, but is now. Earlier this week water pump failed, so got that replaced, even though it was replaced at 115k, 7 months ago. It is still leaking and the coolant has gone a bit dirty, ive had the sniff test done, and it didnt show any hydro carbons, and the colour didnt change and also pressure test on the coolant bottle and pressure was fine. Hope its not the head gasket, my friend said it could be the oil cooler. Any help or guidance would be appreciated.