My E550 had a sudden "kflopping' noise in the right side of the front of the car. It sounded like something was flopping into something, was very loud and lasted for several minutes. After pulling over and stopping the car it did not repeat.

Yesterday, about 3 weeks later, it did the same thing again. It seemed to do this if the AC was on or the defrost and increasing the fan speed.

I could not get it to do it again after stopping.

Any suggestions of what to ask or describe to the service??

 

wrong forum; this is W220

 

Please go over to the w212 page

However, air in coolant going through the heater core?