We have a 2012 Winnebago ERA 170X. On a 2011 MB 3500 Sprinter Chassis,milages was 4000 when we got it and now its 10,000. Have been bugged by this since day one.
At 2200 RPM we get a horrid loud rattling sound. Have looked under van and checked exhaust routing for clearance and heat shields--all are ok. I placed pink fiberglass insulation between shields and van floor ad sound absorbers. I added pipe insulation on the black and gray water valve pull rods and insulated the parking brake cables.
Still screams at me around 2200 rpm as i up shift through gers!!
I'm at wits end. going to try extending exhaust pipe straight out the back --I think