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Exhaust leak sound while under load

hotrdlx

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pfmg Enthusiast

pfmg

Posted
Posted

Had it in the 2014 5.3, I just got rid of. Dealer spent lots of time trying to find it. It is not the flapper valve. My dealer thinks it's in the tranny, but mine stop after it warms up. The dealer said they need it to happen more, to try to find it. Crazy, one of final reasons I got rid of it.

jlilnc14 Enthusiast

jlilnc14

Posted
Posted

what does the noise sound like? My truck makes a noise like a semi-truck engine braking when I am lightly/med accelerating from 1250-1700 RPMs. If I accelerate harder, it turns to normal sounding acceleration noise.

  • 1 year later...
f8l vnm Senior Enthusiast

f8l vnm

Posted
Posted

My 16 does it as well. 

Normal stuff. Atleast that’s what gm will tell you 

badge171 Enthusiast

badge171

Posted
Posted

Exhaust manifold leak usually at manifold  to exhaust system joint, Start your truck , get your hand close to the joint, you will hear, and feel the leak if that's the source.

  • 2 months later...
iwannaseeatnight Enthusiast

iwannaseeatnight

Posted
Posted

My '17 denali 6.2 started this around 2 months ago, at around 4k miles, and has gotten progressively louder.  Held the phone down by my feet and recorded it.  Played it for the service dept. during my scheduled service last week and was told it was "normal", due to the exhaust valve for 4cyl mode.  If that was the case, why hasn't it done it from the beginning, and why is it getting louder?  But "there's nothing they can do".  I guess that's what professional grade sounds like!

mferry22 Enthusiast

mferry22

Posted
Posted

Im bringing my truck in tomorrow for this noise and also a very noisy drivers seat. I had an exhaust shop check my exhaust for leaks or anything loose, they didn't find anything. I also had the flapper valve removed so thats not it.

ChristopherDB Enthusiast

ChristopherDB

Posted
Posted
1 hour ago, mferry22 said:

Im bringing my truck in tomorrow for this noise and also a very noisy drivers seat. I had an exhaust shop check my exhaust for leaks or anything loose, they didn't find anything. I also had the flapper valve removed so thats not it.

Good luck. My truck has been at the dealer for 6 days now with no progress. They said they can't do anything about it. I called Chevy an hour ago to open up a case.

Jaychevy81 Enthusiast

Jaychevy81

Posted
Posted

If I had to guess it’s the V band clamp had the same issue on mine once I changed the exhaust tried 10 diff ways to position that clamp still leaked. I picked up some permatex exhaust sealer put a little around where the 2 mate up. Put the clamp on solved it.


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2016LTCC Enthusiast

2016LTCC

Posted
Posted
15 hours ago, Jaychevy81 said:

If I had to guess it’s the V band clamp had the same issue on mine once I changed the exhaust tried 10 diff ways to position that clamp still leaked. I picked up some permatex exhaust sealer put a little around where the 2 mate up. Put the clamp on solved it.


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Did you do this on you 2015? And where exactly is the V-band clamp located?

Jaychevy81 Enthusiast

Jaychevy81

Posted
Posted
Did you do this on you 2015? And where exactly is the V-band clamp located?

I did it on my 2018 but I think the 15 is the same it’s right under the passengers side floor. Noticed it more on cold starts.


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2016LTCC Enthusiast

2016LTCC

Posted
Posted
28 minutes ago, Jaychevy81 said:


I did it on my 2018 but I think the 15 is the same it’s right under the passengers side floor. Noticed it more on cold starts.


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Were you hearing the ticking sound on the drivers side footwell/firewall during acceleration and did this fix that?

crushNchowda Senior Enthusiast

crushNchowda

Posted
Posted

I have this too, have noticed it for some time. I have a gibson dual catback, it is 110% coming from the driver's side front manifold/cat area. I was doing a thorough cleaning of my truck over the holiday weekend & sprayed down the engine bay to get rid of all the pollen/dirt buildup see if I could notice anything. It DOES look like there may be an issue w/ the manifold/header gasket.....can't be 100% certain though....funny thing is for as long as I've been interested in cars GM's gaskets have had the reputation of being top notch (header gaskets anyhow) - I also noticed that my steering rack was heavily oxidized/rusted in like a 2-3" section only - closest to the manifold area, could be just coincidence & from heat, but seems suspicious

 

The thing is the passenger's side didn't look all that different to me, I will get some pics & post today, this was an issue I kinda let go (I did notify dealer they couldn't find the cause either but acknowledged the noise) - the only difference I could sort of see was it APPEARS that the driver's side cat area of the exhaust looked more sooty - however it's also tougher to get a look at the passenger's side due to the placement/light.

 

Lastly, I should also mention that the sound seemed to get louder after adding the catback, which seems counter intuitive because one would think the louder exhaust would drown out some of the exhaust leak noise (if that's what it is) - I do not think the catback could have caused/increased the noise/leak because it doesn't go up that far - the sound comes from a part of the exhaust well before the aftermarket exhaust starts. Now - it could be that the better exhaust flow reduces backpressure & causes the leak/sound to increase? My understanding is the stock exhaust flows OK minus the mufflers. It could also be that I shifted the exhaust around some when installing the catback & maybe loosened a fitting/connection up front where the leak originates from as well?
 

Seems to be getting louder - maybe I'll just throw a CAI on it & hope it drowns the noise out some lol!

 

Honestly - may just drop it off @ an exhaust shop, let them track down the culprit & be done w/ it. I noticed another poster mentioned increase in noise after installing catback, which leads me to believe that it may very well be a clamp/connection point.

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