It was 19 degrees this morning... The Cummins fires right up no problem, but for the first time after it cranked I started to hear this strange sound that I guess I'd describe as a "whirring" sound... Not high pitch, but no low enough to be a groan... It was tied to the belt system I guess, because the sound went directly with the rpm's as I went through the gears... I could feel a slight vibration in the steering wheel and brake pedal as well... I thought it was just cold related but it lasted the entire 15 minutes that it took to get to work... Something in the fan clutch, frozen moisture in the power steering or brake line...? I don't know, never heard this before...