Rattling noise sounds like heat shield.

[KShi]

Hi everyone,

 

I'm new to this forum, I have a 2019 GMC Sierra SLT.  I'm having trouble figuring out where the metal clinging noise is coming from under my truck. The sound only happens when the truck is warm and driving at a constant speed. It will not rattle when I'm accelerating or decelerating etc.  I'm having trouble getting it to rattle parked in the driveway and this is why it's difficult to figure out.  I checked all the heat shields and they seem to be pretty secure with the dealership saying the same thing. I've also looked around to see if I have any clinging marks anywhere to no avail. I've gone over the mileage for the bumper to bumper warranty and the dealership wants to charge me to figure it out.  Has anyone had this same issue or similar experiences and figured out the problem?

[Therickyp]

My truck did the same thing when i first got it and it was the shield around the spare tire. Its easy to bend.  

[eppieguy]

There also have been some reports of the internal muffler rattling, mine is doing it, just waiting for another reason to,go to the dealer to get it replaced. 

[AJMBLAZER]

Check your exhaust flapper(s).  
 

My wife’s Yukon was doing something similar. Was the flapper valve in front of the muffler. 
 

Removed it. No more noise. 

[KShi]

@eppieguy yes, tapping on my muffler it seems to be coming from the inside of it.  Have you had this checked out yet?  Do you know if its covered under warranty? 2019 GMC sierra with 48k miles.  Not sure what warranty this would be classified under but maybe bumper to bumper, which I wouldn't qualify because my miles.  

[eppieguy]

No, I have not had it checked out but I saw a post from another member and it was warrantied for him. I am waiting until I need something else fixed before I bother with it, my warranty expires in December and I have 30k on it so if nothing else crops up between now and then I'll take it in December. It's really not bothering me so right now I don't really care and if I can find a GM performance exhaust before then I won't even take it back. 

[KShi]

Thanks everyone, It was the baffles inside the muffler as I suspected from tapping on the muffler.  Going to do an aftermarket exhaust (bolt on) as they quoted me $1,350 to have the muffler replaced which is crazy.  I am over miles on bumper to bumper and my Ally major guard extended warranty apparently doesn't cover the costs.  Hope this helps someone. 

[AJMBLAZER]

Any good exhaust shop would put the 3 inch muffler of your choice under your truck for a couple hundred bucks tops.

[David T Harrington]

Just had the same rattle issue. 2019 GMC Sierra 1500 SLT Crew Cab Short Bed with 16,500 miles.

 

Only happens when it's hot. Sounds like a heat shield is loose. Especially noticeable with the rear slide window open.

 

It's an internal baffle in the muffler that has come loose. Part number for my repair was 84657793 which is the muffler, pipe and brackets. The part list price is over $800.00.

 

Mine got worse over time, mine would do it really bad at medium speed, about 45 mph.

 

To prove it while stationery, get it good and warm and tap the muffler with a rubber mallet.

 

Mine was covered under factory 36 month / 36,000 mile warranty. 

[RDP3271]

My 2020 Silverado RST is doing the same.  Sounds like a small chain rattling, but only starts after engine gets hot (maybe after 15 or 20 miles).  When I leave my house I can tell exactly where it will start. 

 

Edited August 31, 2024 by RDP3271
spelling

[Sharon Chevy scams]

On 3/28/2021 at 10:26 AM, eppieguy said:

There also have been some reports of the internal muffler rattling, mine is doing it, just waiting for another reason to,go to the dealer to get it replaced. 

I just got a call from the dealership. 21 Silverado just hit 30k and I have now put 2200 miles on it. The baffles inside the muffler are broken and makes a noise over bumps and while hitting brakes. They are saying $1200 to replace the muffler and fix properly. 2200 miles and my bumper to bumper platinum doesn’t cover! Sharon Chevy in Clay NY are scumbags!! I buy multiple vehicles from them out of convenience and always end up with regret! Terrible customer service, attitudes, and all around ****ing dirtbags! 

[Silverado4x4]

21 hours ago, Sharon Chevy scams said:

I just got a call from the dealership. 21 Silverado just hit 30k and I have now put 2200 miles on it. The baffles inside the muffler are broken and makes a noise over bumps and while hitting brakes. They are saying $1200 to replace the muffler and fix properly. 2200 miles and my bumper to bumper platinum doesn’t cover! Sharon Chevy in Clay NY are scumbags!! I buy multiple vehicles from them out of convenience and always end up with regret! Terrible customer service, attitudes, and all around ****ing dirtbags! 

Maybe you need to read your contract on warranty platinum coverage before you call your dealer scumbags cause you didn't get your way on your 1st post. It's a wear item. 

GM Platinum coverage does not cover the following: 

 

• Batteries and cables: Batteries, battery cables, and battery harnesses
• Lenses, lights, and bulbs: Lenses, sealed beams, and light bulbs
• Key fobs and tire pressure sensors: Key fobs and tire pressure sensors
• Brake rotors and drums: Brake rotors and drums
• Exhaust components: All exhaust components, unless specifically listed as covered
• Trim items: Trim items
• Tires and wheels: Tires and wheels/rims
• Maintenance services: Routine maintenance services
• Modifications: Modifications to the frame, suspension, engine, transmission, or drive axle
• Odometer: If the odometer stops working or is altered after the contract is purchased
• Salvaged or rebuilt vehicles: If the vehicle has been salvaged, rebuilt, or is a gray market vehicle

[MC40]

2020, with 6.8 Liter i spent $1000 having the entire truck Rust proofed. All the Straps holding the SS Muffler shield on all rotted off. WTF 45,000 miles truck sounds like a bag full of empty cans.

[Bert23]

So I was having a similar issue on my 2020 trail boss. It only happened between 25-30 mph oddly enough. Finally got under the truck and started banging around. Isolated the noise to the stock skid plate. Figured a rock was on it somehow. Dropped the plate and found a 13mm nut!  Lord knows where that came from. But the rattling is gone!