Hello, I have changed a Brava 1.9TD and briefly my cooling water. Did everything exactly according to the manual and unaired cleanly. Works perfectly except for the heating. When I stand in the traffic jam after approx.10.15 min. only cold air, as soon as I start again comes normal warm air. When I turn off the engine one hears a whistle on the lid of the balancing tank. When I open this, the water rises almost to the very top (so far above the MAX marking) . There is a bubbling to hear. Who has a tip? Thank you very much