ZL1 exhaust leak? Metallic sound at cold start - Page 2

NG329 · 08-24-2022, 10:44 AM

slightly off topic but I notice different sounds from the engine when swapping different oil brands and viscosities. ...also when the oil needs to be changed as well due to it being broken down.

Wuiquen · 08-27-2022, 03:28 PM

I have the same issues. Mine actually never goes away. It is always present at lower RPMs in all gears no matter how long you have driven the car for. It sounds like there are loose screws or nuts in the cats or exhaust manifold. I stopped caring about it and figured it was normal as i got the same response you are getting that it is a normal noise. I am close to swapping to LT headers and exhaust to the cat back so if it goes away, i will know for sure it was the OEM cats. My secondary cats, x pipe, and muffler were replaced under warranty and it didnt affect this. This is why I think it is on the front part of the system.

AMOR · 08-27-2022, 08:22 PM

Quote:

Originally Posted by Wuiquen

I have the same issues. Mine actually never goes away. It is always present at lower RPMs in all gears no matter how long you have driven the car for. It sounds like there are loose screws or nuts in the cats or exhaust manifold. I stopped caring about it and figured it was normal as i got the same response you are getting that it is a normal noise. I am close to swapping to LT headers and exhaust to the cat back so if it goes away, i will know for sure it was the OEM cats. My secondary cats, x pipe, and muffler were replaced under warranty and it didnt affect this. This is why I think it is on the front part of the system.

Thanks for the feedback! It is nice to know that it’s the front part of the system (or the engine itself?). Once you replace the LT headers and if the sound will be gone - please let us know here in this thread.

P.S. Sound does not go away entirely for me either, it is very audible at cold start, then when engine heats up and RPM’s drop - it becomes practically unnoticeable. But when you start applying throttle to get moving while releasing the clutch, sound is very pronounced at lower RPM’s.

Mac7504 · 08-29-2022, 02:34 AM

Yes it's common in these cars... I personally didn't notice mine "tick" until 600 miles in, and only after reading this forum. Mine, however goes away shortly after cold start. Some have said you can get rid of it by performing a tsb for npp rattle, it requires shaving the one of the dog ears off the actuator iirc.
Mine sounds like it's coming from the middle of the car and at first it bothered me because I want a perfect car, but it legit goes away after a min or less.

Get the car on a lift, start it and see what it leads to?
I don't think it's far upstream from 2nd cats. I really feel like you have the npp rattle. Just my take man.

Edit: if it bothers you that much, take it to the dealer or switch out to a catback system.

AMOR · 10-16-2022, 11:02 AM

Man, this ticking sound is really bothering me. It's so loud that can be heard clearly with doors/windows closed, every time I start the car. I am wondering if swapping oil back to higher viscosity 0w40 will help address this issue? Since I track my car, I'm running factory recommended 15w50, but I do not swap it back, so it's essentially in there full time.

08-27-2022, 03:28 PM	#16
Wuiquen Drives: 2018 Hot Red ZL1 Join Date: Nov 2010 Location: Los Angeles, CA Posts: 3,599	I have the same issues. Mine actually never goes away. It is always present at lower RPMs in all gears no matter how long you have driven the car for. It sounds like there are loose screws or nuts in the cats or exhaust manifold. I stopped caring about it and figured it was normal as i got the same response you are getting that it is a normal noise. I am close to swapping to LT headers and exhaust to the cat back so if it goes away, i will know for sure it was the OEM cats. My secondary cats, x pipe, and muffler were replaced under warranty and it didnt affect this. This is why I think it is on the front part of the system. __________________

08-24-2022, 10:44 AM	#15
NG329 Drives: Chevrolet Camaro ZL1 1LE Join Date: Oct 2021 Location: NY Posts: 702	slightly off topic but I notice different sounds from the engine when swapping different oil brands and viscosities. ...also when the oil needs to be changed as well due to it being broken down.

08-29-2022, 02:34 AM	#18
Mac7504 Drives: 2003 Monte Carlo SS SLP, 2022 ZL1 Join Date: Aug 2021 Location: Los Angeles, CA Posts: 486	Yes it's common in these cars... I personally didn't notice mine "tick" until 600 miles in, and only after reading this forum. Mine, however goes away shortly after cold start. Some have said you can get rid of it by performing a tsb for npp rattle, it requires shaving the one of the dog ears off the actuator iirc. Mine sounds like it's coming from the middle of the car and at first it bothered me because I want a perfect car, but it legit goes away after a min or less. Get the car on a lift, start it and see what it leads to? I don't think it's far upstream from 2nd cats. I really feel like you have the npp rattle. Just my take man. Edit: if it bothers you that much, take it to the dealer or switch out to a catback system.

10-16-2022, 11:02 AM	#19
AMOR Drives: Camaro Join Date: Apr 2021 Location: Miami Posts: 105	Man, this ticking sound is really bothering me. It's so loud that can be heard clearly with doors/windows closed, every time I start the car. I am wondering if swapping oil back to higher viscosity 0w40 will help address this issue? Since I track my car, I'm running factory recommended 15w50, but I do not swap it back, so it's essentially in there full time.

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