Hello again, the KA meier woman is ticking something again. He got a new timing belt with water pump and so on 3 weeks ago. Since then, my wife hears a glimmering or any liquids swarming while driving, so your description. I drove yesterday and actually, standing by the gas, about 2000u/min it sounds centered behind the dashboard as if some water is glimmering/wrapping and with pressure flowing through pipes. Heating only glimmers faster. I don’t have the idea now but my guess is that the system might not have been properly ventilated when changing the water pump and there is air in the heat exchanger or in the whole system? What is this actually ventilating itself or ? Then the air would have to be already out……The cooling water level is about 2cm above max. Or is something defective ?? Sure I can go back to the workshop, however the currently completely booked and little rep. I like to do it myself. Greetings Mickey