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Exhaust Flapper Noise - Will it go away eventually?

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FYI, I don't know if it's because I've been putting more miles on the truck or because the weather is warming up, but the grumbling and rattling seems to have lessened to the point it's almost undetectable. I may just leave things the way they are unless it comes back when it's cold. Just like the transmission, it shifted like crap until I got about 1300 miles on the truck. Then it got better and better. Almost overnight. Weird.........

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  • 1 year later...

Hello ! I know this post is almost 9 months old, still I'm giving a shot.


I've  been experiencing quite the same issue with the flapper valve on my 17' Sierra 1500 for about few months now. When idling (from cold start), it make a rattling sound (which basically is the spring that rattles between the plates). By rotating it open (or close), it stops right away (see video : https://drive.google.com/file/d/1hnIOqZiJW_2hH9cbu5P9FsG36N74UVz9/view?usp=drivesdk  )


As you can see, the design (plates on each side of the spring) has slightly changed over the years (now more of a rounded shape, not square anymore), but it hasn't keep it from doing that annoying sound lol...




Dealership says they can't do anything about it (of course they don't want to replace the whole exhaust)... and I don't really want to do a full muffler delete or changing the whole exhaust system. So after reading this thread, I thought I would clamp the valve open (and call it a day). Only question I got : I know I need to do a 1/4 turn first to open it, but do I turn it clockwise or counter ? 


Thanks !


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18 hours ago, Elevation_2017 said:

Dealership says they can't do anything about it (of course they don't want to replace the whole exhaust)

Find another dealer.  You have a valid complaint under warranty.  There is an existing PIT telling them to replace the cold side of the exhaust.  If they don't want to do it they are just giving you the runaround.

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