I have a MK.3 8v Gti Golf.

Basically, My coolant seems to completely dissappear a couple of weeks after filling it right up. Last time I filled it up I did it with normal water and not a mix of anti freeze just to temp. top it up, but I doubt this has had an effect.

Has anyone else heard of this problem or could give me an insight as to what the problem might be. My worst worry is that its the head gasket but the engine is running smooth and I havent seen any white smoke. Also there are no puddles under the car so where is the water going??

Any suggestions will be greatlyappreciated. Cheers.