Exhaust Rattle Noise returns after exhaust was replaced

CamaroGen6 · 04-14-2019, 08:36 AM

Has anyone else had the exhaust rattle noise return after having the exhaust replaced by Chevy? I first had this issue last year in August 2018 at under 12k miles. They tried the epoxy fix and after that didn't work the entire exhaust was replaced. I have the NPP exhaust.

I'm now at 21k miles and the rattling noise has returned. I first noticed it this cold, wet morning (45f). It seems to be more noticeable when the weather is cooler (also happened the first time). What's different this time, however, is that it's like 50% less noticable. It's not as loud as the first time; if I put it in tour mode you can barely hear it and in sport mode it gets completely masked out. Stealth mode is the only way an untrained ear can hear it..

I already have a service appointment set up for Monday morning on an unrelated issue and I will be adding this to it. But I would like to know if anyone else has experience the return of the rattle noise and what was Chevy's response after already replacing the exhaust.

Deesiel678 · 04-14-2019, 10:43 AM

Subscribed. This is disheartening.
My npp exhaust is due to be replaced some time this week when they get it in stock. I'm still on my original exhaust; I have approximately 12k mi. I'm also interested in hearing any experiences of having the second exhaust replaced and/or repaired (or whatever Chevy's response has been).

Experiencing the same issue less than 10k miles later makes me think I should just go with aftermarket.

Danelt2017 · 04-14-2019, 12:47 PM

I assume the noise is coming from the NPP valve system? Do you have a recording of the sound?

Deesiel678 · 04-16-2019, 07:50 AM

Quote:

Originally Posted by Danelt2017

I assume the noise is coming from the NPP valve system? Do you have a recording of the sound?

You can hear it in my track video. It's not really present during the first lap, but it gets progressively worse each lap. You can hear it most when I'm rolling in to the throttle around 4k RPM.

I recorded this around 2 weeks ago. Reviewing this video was the first time I noticed it. I didn't notice it while recording (I was focused on driving obviously). Since then, its gotten worse. I definitely notice it during my daily commute. In the video it seems valve related (I assume the valves open fully around 4k RPM but I'm not sure). Now, it seems like something is loose in the muffler. It rattles no matter if the valves are open or closed, at idle and on throttle.

I took it to the dealership about a week ago. They didn't even bother with applying the valve fix; they ordered a replacement the same day, on my first visit for this.

CamaroGen6 · 04-16-2019, 08:44 AM

So oddly enough, the rattling noise was only present on that cold morning when I made the original post. It has warmed up since then and I couldn't replicate the noise after that day. On my drive to the dealership yesterday I could no longer hear it, not even in stealth mode. I still informed the service advisor about it but the likelihood of the technicians doing anything about it when the issue is no longer present is slim (what the advisor told me). For the record I did go to a different dealership since they were the only ones who could provide me with a loaner car. If it comes back, however, I will take it to the dealership that originally replaced the exhaust since they are more familiar with me and the exhaust defect.

If anyone needs the service bulletin for it here it is:
https://static.nhtsa.gov/odi/tsbs/20...82403-5448.pdf

On my original post I mentioned that I was taking it to the shop for an unrelated issue. This was due to the check engine light coming on. They did look into that and turns out that a "exhaust cam solenoid" went out and will be replaced under warranty. Not sure if that had anything to do with the noise I was hearing or not.

302Blue · 04-16-2019, 10:14 AM

Kind of off-topic, but I eventually want to replace my exhaust with the NPP Borla S-Type or Atak system.

Does anyone know if these problems re-occur on the aftermarket NPP systems directly from Borla?

cellsafemode · 05-09-2019, 10:57 AM

interesting. I get this exact sound from my MRT exhaust now and it's axle back. I have no NPP valves. It sounds like maybe there is something that has a spot weld broken in the resonator. I still have stock resonator in my system, did you before they replaced the entire exhaust?

I'm convinced now that this is either in the resonator or adjacent to the exhaust on the body since we're both hearing the same exact thing.

I purchased a welder thinking a spot weld on the MRT tips broke and i was going to fix it this weekend but now I'm pretty sure it's going to be something internal to either the resonator or not part of the exhaust system at all.

edit: fyi, when i refer to "resonator" i'm referring to the stock x pipe "resonator" and not the secondary cats like some exhaust manufacturers are doing. (attached a picture of a stock system - not mine - pointing out where I believe the source of the sound is coming from now)

Looks like there are no aftermarket options for X pipes for the V6 that dont also require deleting the secondary cats - which is not federally legal and not something I can depend on getting away with where I live. So no option that isn't going to require custom fabrication. Fun. Guess i'll have to run my options by an exhaust shop and see what they can create for me since nothing exists that welds/clamps up to the location of the pipes after the secondary cats.

cellsafemode · 05-10-2019, 01:39 AM

If it isn't that x pipe / resonator, then it has to be exhaust shielding nearby.

Camaro owners have apparently been having this sound occur since the 2016 was released and it has nothing to do with npp or stock axle back exhaust components.

cellsafemode · 05-11-2019, 03:34 PM

So I found where this metal grinding vibration sound is coming from. It's definitely the heat shielding above the secondary cats and also between the primary and secondary cats. None of the bolts are loose, this is just harmonic frequency vibration between pieces of metal that have no business being as close together without being securely attached as they are.

100%

I managed to get rubber gasket material between all of the metal parts that i could reach. Unfortunately, it looks like to solve the issue you need to pad all of it that is in close proximity to the body or you risk still having the vibration occur.

F YOU chevy for putting thin aluminum against metal. It's like someone gets paid to think of ways to make camaro's vibrate. Whether it's the internal plastic body parts and switches that vibrate whenever you listen to music or apparently the heat shielding from even the stock exhaust vibration. I HATE YOU. So unbelievably pissed right now. Will probably have to take this to a trusted mechanic with a lift to have them drop the exhaust and pull all of the heat shielding and properly pad them.

edit: and surprise, this has been happening since the 5th gen as well.

Apxj · 05-11-2019, 09:55 PM

Quote:

Originally Posted by cellsafemode

interesting. I get this exact sound from my MRT exhaust now and it's axle back. I have no NPP valves. It sounds like maybe there is something that has a spot weld broken in the resonator. I still have stock resonator in my system, did you before they replaced the entire exhaust?

I'm convinced now that this is either in the resonator or adjacent to the exhaust on the body since we're both hearing the same exact thing.

I purchased a welder thinking a spot weld on the MRT tips broke and i was going to fix it this weekend but now I'm pretty sure it's going to be something internal to either the resonator or not part of the exhaust system at all.

edit: fyi, when i refer to "resonator" i'm referring to the stock x pipe "resonator" and not the secondary cats like some exhaust manufacturers are doing. (attached a picture of a stock system - not mine - pointing out where I believe the source of the sound is coming from now)

Looks like there are no aftermarket options for X pipes for the V6 that dont also require deleting the secondary cats - which is not federally legal and not something I can depend on getting away with where I live. So no option that isn't going to require custom fabrication. Fun. Guess i'll have to run my options by an exhaust shop and see what they can create for me since nothing exists that welds/clamps up to the location of the pipes after the secondary cats.

Try welding around the breather hole in the resonator mine cracked and it sounded like glass in my exhaust till it go welded again.

cellsafemode · 05-11-2019, 11:25 PM

It's the heat shields. I've been under the car and heard the metal on metal tin can vibration just like in the video. And the harmonics change when you manipulate the shields.

They are ridiculously thin aluminum sheets that are right against but not touching and the littlest vibration causes them to hit the body. I'm taking them off tomorrow and dynomatting them all.

If in 5 years they still sell the Camaro, I'm going to make sure the heat Shields get corrected on day one. There is no excuse for this garbage

cellsafemode · 05-13-2019, 12:39 AM

Well, dynomatted the aluminum exhaust shields above the secondary cats. Still vibrating something near there. Haven't done the rear Shields yet.

Tomorrow after work I'll get back under and do some better testing with the wife revving the car this time with me under it.

This vibration is worth a mythical curse on the person responsible. I'm 10min away from taking a hammer and going full Clarkson on the entire underside of this car.

cellsafemode · 05-13-2019, 10:14 AM

Put the car up before work and and tightened the bracket that attaches the cats (under them) to the transmission. It wasn't loose but i tightened it anyway.

Also tightened some of the bolts connecting the plastic body panels close to the nose of the car and some of the felt panels just because i was in the area. I originally dismissed them as a potential sound source since they didn't seem to be connecting metal on metal, but they could be covering metal on metal i suppose or maybe the right thickness and type of plastic can make that sound too when hitting metal. I only tightened the ones around me as i was getting out from under the car.

at least 90% of the vibration is now gone. It still makes it for a very short amount of time at a much narrower rpm band so I'll have it back up on the ramps after work but at least now I'm in the right area. Will know for sure after work with the wife hitting the gas with me under. Hopefully not being under load will still let me hit the right frequency.

cellsafemode · 05-13-2019, 08:37 PM

ok, so I got under it while the wife revved the engine and we are able to reproduce the vibration. Whether it was always all coming from this or not, I can guarantee that it's coming from the X-pipe resonator. Stick my screwdriver in the breather hole, and i can absorb the vibration. But there is no crack visible on the external shield. Something internal must have cracked.

So it looks like the only way to fix this is to cut the x-pipe off and replace it with a new one (not another cheap piece of crap from GM to break again). While I have a welder, I dont want to learn on my exhaust

Looks like it's off to a an exhaust shop to custom fab me up something.

04-14-2019, 08:36 AM	#1
CamaroGen6 Drives: 2020 Camaro 2SS Join Date: Feb 2018 Location: Dallas Posts: 54	Exhaust Rattle Noise returns after exhaust was replaced Has anyone else had the exhaust rattle noise return after having the exhaust replaced by Chevy? I first had this issue last year in August 2018 at under 12k miles. They tried the epoxy fix and after that didn't work the entire exhaust was replaced. I have the NPP exhaust. I'm now at 21k miles and the rattling noise has returned. I first noticed it this cold, wet morning (45f). It seems to be more noticeable when the weather is cooler (also happened the first time). What's different this time, however, is that it's like 50% less noticable. It's not as loud as the first time; if I put it in tour mode you can barely hear it and in sport mode it gets completely masked out. Stealth mode is the only way an untrained ear can hear it.. I already have a service appointment set up for Monday morning on an unrelated issue and I will be adding this to it. But I would like to know if anyone else has experience the return of the rattle noise and what was Chevy's response after already replacing the exhaust. __________________ 2020 Camaro 2SS

04-14-2019, 10:43 AM	#2
Deesiel678 Drives: 2018 1LS 1LE Join Date: Jan 2018 Location: Canton, GA Posts: 49	Subscribed. This is disheartening. My npp exhaust is due to be replaced some time this week when they get it in stock. I'm still on my original exhaust; I have approximately 12k mi. I'm also interested in hearing any experiences of having the second exhaust replaced and/or repaired (or whatever Chevy's response has been). Experiencing the same issue less than 10k miles later makes me think I should just go with aftermarket. __________________ 2018 V6 1LE Instagram: @ag1le_v6 YouTube

04-16-2019, 08:44 AM	#5
CamaroGen6 Drives: 2020 Camaro 2SS Join Date: Feb 2018 Location: Dallas Posts: 54	So oddly enough, the rattling noise was only present on that cold morning when I made the original post. It has warmed up since then and I couldn't replicate the noise after that day. On my drive to the dealership yesterday I could no longer hear it, not even in stealth mode. I still informed the service advisor about it but the likelihood of the technicians doing anything about it when the issue is no longer present is slim (what the advisor told me). For the record I did go to a different dealership since they were the only ones who could provide me with a loaner car. If it comes back, however, I will take it to the dealership that originally replaced the exhaust since they are more familiar with me and the exhaust defect. If anyone needs the service bulletin for it here it is: https://static.nhtsa.gov/odi/tsbs/20...82403-5448.pdf On my original post I mentioned that I was taking it to the shop for an unrelated issue. This was due to the check engine light coming on. They did look into that and turns out that a "exhaust cam solenoid" went out and will be replaced under warranty. Not sure if that had anything to do with the noise I was hearing or not. __________________ 2020 Camaro 2SS Last edited by CamaroGen6; 04-16-2019 at 09:00 AM.

05-09-2019, 10:57 AM	#7
cellsafemode Drives: 2016 Camaro 1LT Join Date: Jan 2016 Location: California Posts: 3,491	interesting. I get this exact sound from my MRT exhaust now and it's axle back. I have no NPP valves. It sounds like maybe there is something that has a spot weld broken in the resonator. I still have stock resonator in my system, did you before they replaced the entire exhaust? I'm convinced now that this is either in the resonator or adjacent to the exhaust on the body since we're both hearing the same exact thing. I purchased a welder thinking a spot weld on the MRT tips broke and i was going to fix it this weekend but now I'm pretty sure it's going to be something internal to either the resonator or not part of the exhaust system at all. edit: fyi, when i refer to "resonator" i'm referring to the stock x pipe "resonator" and not the secondary cats like some exhaust manufacturers are doing. (attached a picture of a stock system - not mine - pointing out where I believe the source of the sound is coming from now) Looks like there are no aftermarket options for X pipes for the V6 that dont also require deleting the secondary cats - which is not federally legal and not something I can depend on getting away with where I live. So no option that isn't going to require custom fabrication. Fun. Guess i'll have to run my options by an exhaust shop and see what they can create for me since nothing exists that welds/clamps up to the location of the pipes after the secondary cats. Attached Images Last edited by cellsafemode; 05-09-2019 at 12:03 PM.

05-11-2019, 03:34 PM	#9
cellsafemode Drives: 2016 Camaro 1LT Join Date: Jan 2016 Location: California Posts: 3,491	So I found where this metal grinding vibration sound is coming from. It's definitely the heat shielding above the secondary cats and also between the primary and secondary cats. None of the bolts are loose, this is just harmonic frequency vibration between pieces of metal that have no business being as close together without being securely attached as they are. 100% I managed to get rubber gasket material between all of the metal parts that i could reach. Unfortunately, it looks like to solve the issue you need to pad all of it that is in close proximity to the body or you risk still having the vibration occur. F YOU chevy for putting thin aluminum against metal. It's like someone gets paid to think of ways to make camaro's vibrate. Whether it's the internal plastic body parts and switches that vibrate whenever you listen to music or apparently the heat shielding from even the stock exhaust vibration. I HATE YOU. So unbelievably pissed right now. Will probably have to take this to a trusted mechanic with a lift to have them drop the exhaust and pull all of the heat shielding and properly pad them. edit: and surprise, this has been happening since the 5th gen as well. Last edited by cellsafemode; 05-11-2019 at 03:50 PM.

04-14-2019, 12:47 PM	#3
Danelt2017 Drives: 2017 Camaro 1LT V6 Manual Join Date: Feb 2019 Location: Ky Posts: 18	I assume the noise is coming from the NPP valve system? Do you have a recording of the sound?

04-16-2019, 10:14 AM	#6
302Blue Drives: 2017 Camaro V6 1LE Join Date: Jun 2017 Location: Delaware Posts: 110	Kind of off-topic, but I eventually want to replace my exhaust with the NPP Borla S-Type or Atak system. Does anyone know if these problems re-occur on the aftermarket NPP systems directly from Borla?

05-10-2019, 01:39 AM	#8
cellsafemode Drives: 2016 Camaro 1LT Join Date: Jan 2016 Location: California Posts: 3,491	If it isn't that x pipe / resonator, then it has to be exhaust shielding nearby. Camaro owners have apparently been having this sound occur since the 2016 was released and it has nothing to do with npp or stock axle back exhaust components.

05-11-2019, 11:25 PM	#11
cellsafemode Drives: 2016 Camaro 1LT Join Date: Jan 2016 Location: California Posts: 3,491	It's the heat shields. I've been under the car and heard the metal on metal tin can vibration just like in the video. And the harmonics change when you manipulate the shields. They are ridiculously thin aluminum sheets that are right against but not touching and the littlest vibration causes them to hit the body. I'm taking them off tomorrow and dynomatting them all. If in 5 years they still sell the Camaro, I'm going to make sure the heat Shields get corrected on day one. There is no excuse for this garbage

05-13-2019, 12:39 AM	#12
cellsafemode Drives: 2016 Camaro 1LT Join Date: Jan 2016 Location: California Posts: 3,491	Well, dynomatted the aluminum exhaust shields above the secondary cats. Still vibrating something near there. Haven't done the rear Shields yet. Tomorrow after work I'll get back under and do some better testing with the wife revving the car this time with me under it. This vibration is worth a mythical curse on the person responsible. I'm 10min away from taking a hammer and going full Clarkson on the entire underside of this car.

05-13-2019, 10:14 AM	#13
cellsafemode Drives: 2016 Camaro 1LT Join Date: Jan 2016 Location: California Posts: 3,491	Put the car up before work and and tightened the bracket that attaches the cats (under them) to the transmission. It wasn't loose but i tightened it anyway. Also tightened some of the bolts connecting the plastic body panels close to the nose of the car and some of the felt panels just because i was in the area. I originally dismissed them as a potential sound source since they didn't seem to be connecting metal on metal, but they could be covering metal on metal i suppose or maybe the right thickness and type of plastic can make that sound too when hitting metal. I only tightened the ones around me as i was getting out from under the car. at least 90% of the vibration is now gone. It still makes it for a very short amount of time at a much narrower rpm band so I'll have it back up on the ramps after work but at least now I'm in the right area. Will know for sure after work with the wife hitting the gas with me under. Hopefully not being under load will still let me hit the right frequency.

05-13-2019, 08:37 PM	#14
cellsafemode Drives: 2016 Camaro 1LT Join Date: Jan 2016 Location: California Posts: 3,491	ok, so I got under it while the wife revved the engine and we are able to reproduce the vibration. Whether it was always all coming from this or not, I can guarantee that it's coming from the X-pipe resonator. Stick my screwdriver in the breather hole, and i can absorb the vibration. But there is no crack visible on the external shield. Something internal must have cracked. So it looks like the only way to fix this is to cut the x-pipe off and replace it with a new one (not another cheap piece of crap from GM to break again). While I have a welder, I dont want to learn on my exhaust Looks like it's off to a an exhaust shop to custom fab me up something.

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