2018 Sierra 5.3L 'farting' out the tailpipe,sounds like wipers on a dry window

[Grinnen]

Hi

I've noticed that my Sierra has an issue (besides others that have been fixed). It's done it off an on for a while, the farting out of the tailpipe which sounds almost like a wiper blade going across a dry window.

Today it was very noticeable. Raining out, had cruise control on and was going about 80km/hr and it kept making the same sound, and it can be felt. My wife and I both agreed it sounded like a sound in the exhaust.

Any ideas?

[HeySkippyDog]

You got me to click because you used the word "farting".

Can you send us a video or audio file to hear? I am curious. Does it do it at idle?

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[Grinnen]

I've been trying to get it recorded but even though I can hear it my iPhone won't pick it up.

It's duration and happening is random, and if you know what a wiperblade on a dry window sounds like it sounds identical. Only happens when I'm driving.

[HeySkippyDog]

The flapper in the exhaust for reducing exhaust flow for V4 can make a little squeak. Farts can be squeakers.

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[Grinnen]

That would make sense, it seems to follow changing from/to V4/V8 mode.

 

[HeySkippyDog]

My 2014 made a very quick *EEEEK* when switching to V4. My 2017 sounds slightly less squeakish and more like a bathtub fart.

Watch on the dash screen to see if the sound correlates to switching to V4. Or, Shift to L5 and drive around, since L5 keeps it in V8. If you have no sounds in L5, it's just the flapper and nothing to worry about.

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[BigBlueLB756]

Get two hose clamps and one piece of scrap metal.  Rotate the head of the flapper valve all the way clock-wise and apply the metal and clamps to hold the valve in the open position.  Offending noise eliminated.

 

 

[dieselfan1]

Never trust a fart

[BigBlueLB756]

Especially if you've got cloth seats.

Don't ask.

[JimCost2014]

On ‎4‎/‎6‎/‎2019 at 11:40 AM, HeySkippyDog said:

You got me to click because you used the word "farting".

Can you send us a video or audio file to hear? I am curious. Does it do it at idle?

Sent from my SAMSUNG-SM-J727A using Tapatalk
 

Yea, right there with you,

 

There should be awards on here for best "name of post"!!! I vote for this one so far for 2019.

[JimCost2014]

On ‎4‎/‎6‎/‎2019 at 11:49 AM, HeySkippyDog said:

The flapper in the exhaust for reducing exhaust flow for V4 can make a little squeak. Farts can be squeakers.

Sent from my SAMSUNG-SM-J727A using Tapatalk
 

Squeakers include moisture, not ever good for you or your vehicle.....

[2018GMC]

I just farted 

[2018GMC]

I've noticed a squeak from my 2018 when cold. I do NOT have the flapper anymore, it has been cutout.

 

I was moving my truck in driveway. Let it warm up for 30 seconds until idle dropped down. Noticed when getting out of truck while it was idling, heard a squeek coming from under truck, possibly under cab or under front engine area.

[HeySkippyDog]

Squeakers include moisture, not ever good for you or your vehicle.....

It's the ones that have a burble like a performance car that are the worst.

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[ksiesel]

Is the flapper in the exhaust just pressure driven?  There is no motor or actuator on the flapper?