Are you hearing a metal rattle around 1200-1500 rpm when you let off the gas completely?Confirming my 2018 Rubi suffered from a bad heater core. With less than 300 miles and 12 days at the dealership I finally got it back. Like others have said, it was obvious by the strong smell of coolant in the cab. It sucks to have the whole dash removed on a new vehicle. My concern now is things rattling loose or hearing noises that may be due to the repair.