I started my truck today and heard a very loud whacking noise. It almost sounded like there was a ratchet on the drive belt and every time it went around it went "whack, whack, whack, whack). I heard the noise about 7 times and then on the last time it kind of sounded like something was set free.

It was 55 degrees out, so not too cold...

It's a 2013 RAM 2500 that just hit 43,500 miles.

I heard the exact same noise once last week as well. Once the noise stopped, everything was fine - I put 100 miles on it and never heard it again. It had been sitting for 2 or 3 days before I started it..... I let the plugs warm up and everything before starting it...

Thanks in advance - kind of new to Cummins - I just got the truck about 6 months ago. It has been great - the entire truck looks like brand new really...