Exhaust Metallic Rattle - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

spike87 · 10-14-2014, 12:41 PM

Hi all,

I bought my new Camaro a few months back. It's a 2014 2LT. Everything has been running great except for a strange noise coming from the exhaust. From what I can hear it only happens on the left hand side (no rattle from the exhaust pipes on the right hand side of the car).

Nothing has been modified on the car. This noise only seems to occur from a cold start. It lasts around 30 seconds until I hear a loud clicking noise which sounds like some sort of valve opening/closing. I've also noticed that when I accelerate, the rattle noise starts again.

Here's a short video of the noise:

Any ideas what this could be? It's under warranty so I will be making a trip to the service centre as soon as possible, but I'm just after some ideas of what could be causing this.

Thanks for your help!

RunRS9114 · 10-14-2014, 12:47 PM

I'd like to know what this might be as well. My 2014 2LT has the exact same issue. I took it to the dealership, but they couldn't find anything wrong with it at the time. I resorted to pulling the fuse to keep the flaps open and the sound doesn't occur anymore. I keep meaning to put the fuse back in and get it checked out, but keep putting it off.

Let me know what you find out!

Chevrolet Customer Svc · 10-14-2014, 05:56 PM

Quote:

Originally Posted by spike87

Hi all,

I bought my new Camaro a few months back. It's a 2014 2LT. Everything has been running great except for a strange noise coming from the exhaust. From what I can hear it only happens on the left hand side (no rattle from the exhaust pipes on the right hand side of the car).

Nothing has been modified on the car. This noise only seems to occur from a cold start. It lasts around 30 seconds until I hear a loud clicking noise which sounds like some sort of valve opening/closing. I've also noticed that when I accelerate, the rattle noise starts again.

Here's a short video of the noise:

Any ideas what this could be? It's under warranty so I will be making a trip to the service centre as soon as possible, but I'm just after some ideas of what could be causing this.

Thanks for your help!

spike87,

Sorry that your Camaro has an exhaust noise. I understand the displeasure when dealing with a matter like this. Although you're seeking opinions from others, I'd be happy to communicate your concerns with the Customer Experience Managers (CEM) at your GM dealer of choice. Please know that you're welcome to message us privately if you would like to discuss this further, or if you simply want this matter documented.

Kindly,

William R.
Chevrolet Customer Care

KaBoom1701 · 10-14-2014, 06:30 PM

I just installed the NNP exhaust...

It sounds like your flap that inside the exhaust pipe (outside)ones.

Take another video and this time shot straight in. You'll see the flap open or closed.

Could be that if your OEM NPP setting is to keep the flaps closed during start your not making enough vacuum pressure during cold starts to keep them closed.

I know the OEM system comes with a vacuum tank installed under the passenger side wheel well. I assume this is to store extra vacuum pressure during low pressure situations like cold start ups. This would help keep the flaps closed. If you have a vacuum leak in the system somewhere that could be the issue.

fussboss · 10-14-2014, 08:36 PM

Mine does the exact same thing. Also at times while accelerating it will give a similar rattle. I took it to the dealership and got the same response. I have since put on a CAI and have not taken it back yet because I am sure they will point to that and say sorry. BUT if you, or anybody, can figure it out I will have something to go on. The post above by KaBoom1701 looks good and maybe a start.

KaBoom1701 · 10-14-2014, 10:46 PM

I belive the ZL1 NNP are programed to stay open during start up

Close around 1500-2200 rpm's....then open up around 3000-4000 rpm's again.

This might explain where they don't have this issue.

The V6 might be programed different....stay closed during start up? That's why I want to see a video of a factory NPP system staring down the exhaust as stated above.

spike87 · 10-15-2014, 09:13 AM

It is definitely the valve that is causing the loud clicking noise but I'm not sure if it's the same thing that's causing the rattle on acceleration and on cold starts. Here's a video shot straight down the exhaust. The valve seems to close then reopen a couple of seconds later:

http://youtu.be/LsxoFWVCfA0

KaBoom1701 · 10-15-2014, 09:53 AM

Quote:

Originally Posted by spike87

It is definitely the valve that is causing the loud clicking noise but I'm not sure if it's the same thing that's causing the rattle on acceleration and on cold starts. Here's a video shot straight down the exhaust. The valve seems to close then reopen a couple of seconds later:

http://youtu.be/LsxoFWVCfA0

Ok, here's my theory....

Under cold starts and hard acceleration the valves need extra vacuum pressure to stay closed. For some reason you system is not making enough vacuum pressure to overcome the exhaust pressure put on the NPP valves and is forcing them open during cold start and hard acceleration situations.

Have you verified you have these components in the picture below and all vacuum tubes are securely in place?

dmginc · 10-15-2014, 10:23 AM

based on the 2 videos (i assume the one looking into the exhaust was a warm start) i would say it is the butterfly valve opening and closing rapidly from lack of vacuum.

spike87 · 10-15-2014, 12:25 PM

Quote:

Originally Posted by dmginc

based on the 2 videos (i assume the one looking into the exhaust was a warm start) i would say it is the butterfly valve opening and closing rapidly from lack of vacuum.

You're right, the one looking into the exhaust was a warm start. It takes hours for the thing to cool down here in Dubai! I will try and get another video looking into the exhaust on a cold start.

The car is going in to the dealer for them to check it next week so I will report back with any news.

Thanks very much for all your replies.

KaBoom1701 · 10-15-2014, 12:31 PM

Quote:

Originally Posted by spike87

You're right, the one looking into the exhaust was a warm start. It takes hours for the thing to cool down here in Dubai! I will try and get another video looking into the exhaust on a cold start.

The car is going in to the dealer for them to check it next week so I will report back with any news.

Thanks very much for all your replies.

Good luck and keep us informed.

I'm curious now. lol

Chris14RS · 10-16-2014, 09:26 AM

Exhausts with moving parts inside will rattle.

spike87 · 10-28-2014, 06:22 AM

The car went in this morning to have the exhaust checked. Luckily there was no vacuum leak. I was told that part of the exhaust was touching one of the pipes and that was causing the rattle. Strange how it only happened on cold starts and acceleration though!

The outcome is that some sort of spacer has been placed between the 2 metal components that were touching. I have been driving it all day trying to replicate the noise and can't hear it. Looks like the problem is solved!

10-14-2014, 12:47 PM	#2
RunRS9114 Drives: 2017 Hyper Blue 2SS, A8, NPP Join Date: Dec 2013 Location: Chicagoland Posts: 73	I'd like to know what this might be as well. My 2014 2LT has the exact same issue. I took it to the dealership, but they couldn't find anything wrong with it at the time. I resorted to pulling the fuse to keep the flaps open and the sound doesn't occur anymore. I keep meaning to put the fuse back in and get it checked out, but keep putting it off. Let me know what you find out! __________________ Robbie "Would you not like to be, sitting on top of the world with your legs hanging free?"

10-14-2014, 06:30 PM	#4
KaBoom1701 KaBoom1701 Drives: 13' ZL1 Red M6 Join Date: Dec 2012 Location: I.E. SoCal (Yucaipa) Posts: 8,630	I just installed the NNP exhaust... It sounds like your flap that inside the exhaust pipe (outside)ones. Take another video and this time shot straight in. You'll see the flap open or closed. Could be that if your OEM NPP setting is to keep the flaps closed during start your not making enough vacuum pressure during cold starts to keep them closed. I know the OEM system comes with a vacuum tank installed under the passenger side wheel well. I assume this is to store extra vacuum pressure during low pressure situations like cold start ups. This would help keep the flaps closed. If you have a vacuum leak in the system somewhere that could be the issue. __________________ Mods: Roto-Fab Intake, WW Res. kit & Big Gulp Air Scoop, Elite Catch Can, ATI Super Damper & 18% OD Pulley, LF Idler pulley bracket, Metco CC breather, ID850 Injectors, Stainless Power Headers w/ ceramic coating, TR71X Spark Plugs, JMS Fuel Pump Booster, Bo White TB, Tuned by Ted @ Jannetty Racing, Ron Davis HX, D3 Reservoir, Pfadt 1" Springs, Moreno Camber Plates, ZL1 Addons Splitter guard washers, Tow Hook kit & rock guards, Hurst Shifter Billet Plus 6 Speed Short Shifter, ZL1 DRL lighting harness, ZL1 Recaro Seats.

10-14-2014, 10:46 PM	#6
KaBoom1701 KaBoom1701 Drives: 13' ZL1 Red M6 Join Date: Dec 2012 Location: I.E. SoCal (Yucaipa) Posts: 8,630	I belive the ZL1 NNP are programed to stay open during start up Close around 1500-2200 rpm's....then open up around 3000-4000 rpm's again. This might explain where they don't have this issue. The V6 might be programed different....stay closed during start up? That's why I want to see a video of a factory NPP system staring down the exhaust as stated above. __________________ Mods: Roto-Fab Intake, WW Res. kit & Big Gulp Air Scoop, Elite Catch Can, ATI Super Damper & 18% OD Pulley, LF Idler pulley bracket, Metco CC breather, ID850 Injectors, Stainless Power Headers w/ ceramic coating, TR71X Spark Plugs, JMS Fuel Pump Booster, Bo White TB, Tuned by Ted @ Jannetty Racing, Ron Davis HX, D3 Reservoir, Pfadt 1" Springs, Moreno Camber Plates, ZL1 Addons Splitter guard washers, Tow Hook kit & rock guards, Hurst Shifter Billet Plus 6 Speed Short Shifter, ZL1 DRL lighting harness, ZL1 Recaro Seats.

10-15-2014, 10:23 AM	#9
dmginc Drives: In Circles Join Date: Mar 2011 Location: South Carolina Posts: 3,433 View My Garage	based on the 2 videos (i assume the one looking into the exhaust was a warm start) i would say it is the butterfly valve opening and closing rapidly from lack of vacuum. __________________ CAI Cold Air Intake, BMR Strut Tower Brace, BMR 1.2" Lowering Springs Gen5DIY Fog Lights, Big Worm Third Brake Light/Side Marker Tint (Charcoal) GTS Tail Light Covers, Purple Under Hood Lighting Magnaflow Resonated X-Pipe w/ Muffler Delete Black Plasti Dipped Wheels, Z/28 Spoiler

10-16-2014, 09:26 AM	#12
Chris14RS Drives: RRM RS v6 Join Date: Mar 2014 Location: United States Posts: 204	Exhausts with moving parts inside will rattle. __________________ Magnaflow X - pipe MRT V2.0 CAI Intake BARTON SS Airlift Suspension V2 Niche Targa 20x10.5

10-14-2014, 08:36 PM	#5
fussboss Drives: 2014 2LT RS Join Date: Sep 2013 Location: San Diego Posts: 282	Mine does the exact same thing. Also at times while accelerating it will give a similar rattle. I took it to the dealership and got the same response. I have since put on a CAI and have not taken it back yet because I am sure they will point to that and say sorry. BUT if you, or anybody, can figure it out I will have something to go on. The post above by KaBoom1701 looks good and maybe a start.

10-15-2014, 09:13 AM	#7
spike87 Drives: Camaro 2LT RS Join Date: Oct 2014 Location: Dubai, UAE Posts: 7	It is definitely the valve that is causing the loud clicking noise but I'm not sure if it's the same thing that's causing the rattle on acceleration and on cold starts. Here's a video shot straight down the exhaust. The valve seems to close then reopen a couple of seconds later: http://youtu.be/LsxoFWVCfA0

10-28-2014, 06:22 AM	#13
spike87 Drives: Camaro 2LT RS Join Date: Oct 2014 Location: Dubai, UAE Posts: 7	The car went in this morning to have the exhaust checked. Luckily there was no vacuum leak. I was told that part of the exhaust was touching one of the pipes and that was causing the rattle. Strange how it only happened on cold starts and acceleration though! The outcome is that some sort of spacer has been placed between the 2 metal components that were touching. I have been driving it all day trying to replicate the noise and can't hear it. Looks like the problem is solved!