So, it all started when I got a CEL for the Coolant Temp Sensor. So I changed it with a new green version. The light went away, but apparently I did something stupid with the sensor clip as it was not tightened properly. So when I took it out for a drive, the coolant started leaking.. vapor.. smoke etc.. Had to take everything apart and make sure the sensor was put in right. I then filled up the expansion tank with more coolant/distilled water until the max line and took it for a ride again.. The temp gauge was hitting high and once again the coolant in the expansion tank had dissapeared. I check for leaks, but couldn't find any.. no vapor, no smoke.. just the engine heating up and the coolant gone! Could it be that it needs more coolant?

I should mention that I also put in a RAM intake when I put the temp. sensor. I VAG'd the engine blocks 02/03 for the injectors/MAF etc and they all look fine, within the range.

Has anyone got any idea what's going on? I'll probably go get some more coolant tomorrow.