Hi guys. I replaced the thermostat on my 1.8t a4 today. Now im not getting any hot air through the blowers and the coolant doesn't seem to be circulating. I have drained and bled the system 3 times as per the guides on here ie sliding the heater intake back to the bleed hole until water comes out etc. but still the same issue. I have removed the new thermostat again with the housing and when i put it in boiling hot water it doesn't seem to be letting water through the inlet, it just sits in the tube. Would a faulty thermostat cause me not to get coolant circulating to the heater. When i release the coolant resevoir cap it spews a load off coolant out as if its boiling up. Im worried that it may be the water pump. I intend to refit the old one and test it again but wondered if anyone had any thoughts? Thanks folks, Dan.