Exhaust rattle

[Locom0tive]

 

Out of nowhere, exhaust rattle that sounds like loud marbles in a can happens today after sitting all night. Never happened before and nothing out of the ordinary regarding commute. Anyone have any ideas what it is? System checks out tight and mounts are good. Happens only at the rear. Don't know how to link video so upload is here (make sure to click on speaker at lower right of video to enable sound):

 

https://imgur.com/a/ZGdRTWP

 

[CamGTP]

Start bopping stuff with a rubber mallet while under the truck. Could be inside the muffler or maybe even the exhaust flapper valve making noise.

[catpartsman]

I’ll almost guarantee it your exhaust flapper. Mine made a rattle at times too and I just wired it open until the exhaust needs replaced. I even took mine in under warranty and the dealer told me it was the flapper valve and not to worry about it because it was “normal”.


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[nominion]

I had the same problem. It was the flapper. 

[Locom0tive]

Thank you all, I finally had time this weekend and this proved to be the problem.