Coolant Leak!
 

Hi,

Have a coolant leak on a 2005 Cooper, with no obvious signs of leakage. Coolant tank needs topping up every few days.

Car has been with a mechanic, and initially diagnosed the thermostat housing as the issue which he then replaced. But a week later noticed the we were still losing coolant. So I returned it to the garage and he then diagnosed the head gasket as being faulty, but I'm not convinced. Doesn't seem to be burning coolant (no white smoke), and no white residue under oil cap.

Before I take it to another mechanic for a second opinion any ideas/things to check?

Thanks.