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Exhaust Flapper Rattle - Again


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I'm on my third stock exhaust on my 16 5.3. First two were replaced for the V8/V4 squeak. The one now is the new design with the flapper in front of the muffler. Lasted 6 months now if rattles loudly at idle. Looks like exhaust system #4 will be on order soon.

 

 

 

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I had PEV / Flapper valve replaced at 800 miles on my 16, 5.3, RCSB..

Now with 6800 m, still quiet..

 

Had to prove to service manager,, my old buddy that it was the issue..

Was easy when set to M5 and no squeaking noise since did not transfer between V4 to V8 mode..

Dealership replaced entire exhaust system too...

 

Discovered "rust" on moving parts was cause of tin can squeak noise..

 

So Far,, So Good..

 

Cheers---Keith

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I had the Borla on for a while but took it off to sell to pay some bills. It was nice but It did get annoying when towing my camper. The first two factory exhausts had the flapper after the muffler and would squeak when going v4/v8. Gm redesigned it with the flapper in front of the muffler and the valve itself is different too. The new design doesn't squeak and was quiet till it recently started rattling when idling. The rattle goes away as soon as I put my hand on the valve in the video.

 

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We traded my wife's 14 in on a 17 about a month ago. On the 14 I had the flapper valve removed after we had owned a while and within a week of picking up her 17 I drove it one day and had the valve removed on it. We both think the exhaust tone is a little deeper and have had no other issues with it. To me it was just a big restriction in the stock exhaust.

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I have the GM Borla dual exit on my 2017 6.2l Denali. Luckily I don't have the rattle at idle or when going in out of V4. But I do get a high pitched tin can type of noise when I get on it from 2.5k RPM about 3.5k RPM. If I don't get on it hard I don't hear it. Seems to me like the flapper valve is acting like a reed in an instrument. It might be because I have headers in front of it. It is annoying when I want get on it that is what I have to hear.

 

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I have the GM Borla dual exit on my 2017 6.2l Denali. Luckily I don't have the rattle at idle or when going in out of V4. But I do get a high pitched tin can type of noise when I get on it from 2.5k RPM about 3.5k RPM. If I don't get on it hard I don't hear it. Seems to me like the flapper valve is acting like a reed in an instrument. It might be because I have headers in front of it. It is annoying when I want get on it that is what I have to hear.

 

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Get some chicken wire and wire the valve open. I did that on the Borla flapper when I had it on my truck

 

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Get some chicken wire and wire the valve open. I did that on the Borla flapper when I had it on my truck

 

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I tried wire it open once and got frustrated. I'll give another go and report back.

 

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I tried wire it open once and got frustrated. I'll give another go and report back.

 

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I used a plastic zip tie to hold it open all the way, then wrapped it in metal wire, then cut the zip tie off.

 

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I wrapped a big hose clamp across my factory flapper. Works great.

The new design flapper like I have is round not square like the old one so the hose clamp won't work. Think gm figured out the hose clamp trick on the redesign

 

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Mine is doing that squeak sound when it goes from v8 to v4 mode. I'm taking my truck back to dealer next week to have CD player fixed. My question is...is it worth me having dealer look at that to?

Yes. There is a TSB for it. You will get a new exhaust system, then cross your fingers it doesn't make noise

 

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