Exhaust system rattle

[StephenW]

I have a 2015 Yukon XL Denali that has a rattle under the center of the vehicle. Replaced the muffler, checked all of the heat shields.

Comes in and out at certain RPM’s. Shop thinks it may be the mid-exhaust flex coupling (piece circled in red) but on the Denali’s it is welded into the exhaust system - need a $700 part. Anyone just do a chop and swap of it before? What is a part number that would work? Thanks.

 

[gooffeyguy]

Do you have AFM/DFM (switches from V8 to V4) enabled or disabled?

I know on some model years there is a valve in the exhaust that helps eliminate the noises caused by DFM, and the spring in this valve has been known to cause a rattle.

 

[StephenW]

AFM is enabled. The rattle is more tied to rpm/gear selector than v4/v8 mode. But is there somewhere I can read about this valve?

 

[gooffeyguy]

AFM is enabled. The rattle is more tied to rpm/gear selector than v4/v8 mode. But is there somewhere I can read about this valve?

Thread 'Does Anyone Know What This Valve is Called or What It Does?' https://www.tahoeyukonforum.com/thr...-this-valve-is-called-or-what-it-does.127909/

 

[StephenW]

Can that valve be replaced?

 

[iamdub]

Can that valve be replaced?

Or just cut out and a piece of regular pipe welded in its place. A new valve will fail just the same.

To test if it even is the valve, you can twist it to hold it open and clamp it. There's something called a "bolt mod" that's another way to just hold it in the open position. I've never done one personally, just read up on 'em.

Here's a little something: https://www.tahoeyukonforum.com/threads/bolt-mod.97948/page-2