Brian Gemmill

So my noise cleared up as well after several hundred miles... changed my oil again and noise is back again! Crazy. Im a mechanic, i work on this stuff for a living but as a consumer - it drives me crazy owning a noise i cant explain.

Hello! I own a 2021 3500hd 6.6 gas cab&chassis with what sounds like the same noise. A random light knock noise from the bell housing/rear engine block area only in park or neutral, hot idle started right after my first oil change at 2400 miles. I currently have 2600 miles and noise hasn't changed much in that short time. User "Leem" explained my concern better than I can. My local dealer is stumped. Has anyone else had any further developments?