Hey everyone, I have an Audi A4 2.0T B7. I replaced my thermostat last night. I had ordered a wahler t stat off of europaparts.com. Anyway I get the t stat on, everything put together, start the car, seems fine, turn off car, and i have a leak where the lower coolant hose connects to the thermostat with that plastic quick pull/release coupling. Two things I have noticed. The diameter of intake of the t stat seems a hair smaller that the old t stat, also there is an o-ring inside the lower coolant hose. I managed to get the o ring out. Here is a picture for reference as an attachment. it is a 32x4mm size. Am I safe to assume that this o ring is the culprit? Or is the whaler thermostat not built correctly? This is a bit confusing. I am goin to get a new o-ring today and see if that does the trick. Your thoughts and help are greatly appreciated!

 

This is the thermostat I got.