Tach! Yesterday, for the second time, shortly after the start, I had a pretty bad grinding noise from the engine compartment.. Engine start, ca. 150m driven, then it started. However, until I stood up again, bonnet, out of the car was quiet again and did not occur again. My wife already happened two weeks ago. From the noise I would have typed on eating climate compressor, or amok-running secondary air pump. But the climate cooled and the noise was gone after maybe 15 seconds. Does anyone have an idea about this?