help!!! loosing coolant

[540i]

Hello everybody!

I'm new on this forum and i have a problem with the coolant. I don't know from where i'm loosin it. I looked under the car and it's dry, i've replaced the coolant tank but still i have to refill the tank once a day because the level drops below min. Does anybody know the solution to my problem, a friend of mine said that it might be the tank's cap, and it looses water vapors

thank you

The car is an audi a6 avant 2.5tdi 2003

 

[chopper602]

Have you checked the oil? Is there water in it? Have you noticed steam in the exhaust? Could be head gasket . . . .

 

[540i]

I have checked the oil, the exhaust is clear without any smoke. Well it seems that after I changed the coolant tank the whater level dropped becouse all the air has gone out and now the level remained constant after a few trips. I belive the problem is now solwed, thanks for help