fred.lum

New member here. I have a 2005 C230 Kompressor and have been trying to identify a strange noise being emitted from the engine. It is an automatic and the noise only occurs when the car is in drive or reverse at low idle. The sound goes away when the car is in park. It seems to be coming from the upper right side of the engine near the intake. The car drives fine. Recently replaced the voltage regulator due to issues with the alternator. Other than that, car is original parts from factory. After discovering the sound, I drove the car back home 120 miles with no issues. Can anybody recognize what this sound may be? Thanks in advance.