Hi everyone. New to the forums, but I own 2 so needed to find some like minded petrol heads. My problem is with my 55 plate A3 2.0tdi The expansion bottle seems to fill with air, and expand, pushing all the water/coolant out. Lighting up the coolant level warning light. Ive had the expansion bottle and the thermostat replaced. But it still happens after a long drive. But then I stop and relieve the pressure light goes off, all is well until I take another long drive. Temperature stays at constant 90, fan kicks in, mechanic who replaced the parts is also scratching his head. He did notice alot of K-seal in the coolant. Could this be clogging the pipes? Or the waterpump? Any help would be greatly appreciated. Cheers.