New 2015 Silverado Odd noise

[zicc]

I just leased a new 2015 Silverado LT and am noticing an odd noise. It mainly happens from a stop when I go to take off and doesn't happen all the time. When I hit the gas, there is a rattle like noise. Almost sounds like the anti lock noise when the anti locks kick in. It also happens at low speeds when making a bend. I am going to take it back to the dealer, but it doesn't happen all the time and the noise is very faint, so I am hoping that it will do this when the tech takes it for a test drive. Any thoughts on what this could be?

 

BTW, here is a picture of the new truck. I love it so far.

 

 

[Slo281]

Man that truck is sick. Very nice. Hope it's nothing major

[zicc]

Thanks. I love the color. I asked my dealer about the color and why it is not an option on the Chevy website and he said that the color could not be ordered. Chevy put this color on a few trucks to see how it sold and if it gets a good response, they may offer the color on 2016 models. That made it even more valuble to me.

 

Man that truck is sick. Very nice. Hope it's nothing major

[UrbanRage]

The exhaust flapper dammit thingy might be causing the rattle. I know others have used a hose clamp to hold it open.

[wurgs]

Or add a catback and eliminate the flapper.

[md11forever]

Very nice ride. If they had that color on the Sierra I would have bought it in a heartbeat.

[topshelfproducts]

Cut out resonator to a straight pipe, and cut flapper muffler and put this flowmaster in.

 

 

[zicc]

That did cross my mind about the flapper. I'm not sure how I can hose clamp it open.Is it located right outside the exhaust manifold?

 

I noticed this morning when the truck was cold that it wasn't doing it, but after it warmed up, it started making the noise. I listened today to to try find out where the noise is coming from. If I was coasting around 30, when I would go to give it gas, it would make that rattle noise. It also seems to make the noise when making a bend. I don't hear it at higher speeds which would make sense it being the exhaust flapper. That flapper is only closed when the truck is warming up, correct? It's like the older chevy carburated trucks.

 

I don't want to replace the exhaust since it is a lease. I probably would't anyhow.

 

The exhaust flapper dammit thingy might be causing the rattle. I know others have used a hose clamp to hold it open.

[CounterMeasure]

The flapper is right behind the muffler, etched with "Adaptive Valve" and the part number in the metal I believe. Its "adaptive" because its spring loaded to be closed, but exhaust pressure overcomes the spring tension to open it. You can actually bolt it open, which is an acceptable method per the TSB on the little valve to determine if the valve's movement is the source of a noise. You twist the external knob 90 degrees, and then run a 1/4in bolt behind it, letting the bolt head and washer and nut hold it open. Instead of a bolt, a small hose clamp can be used on the external knob to hold it open.

[zicc]

Thank you. So this could be possibly be making that vibration noise at lower speeds?

[Dropsix]

I had a loose bolt in my front bumper. When i gave the bumper a hit with my palm I could hear a loud rattle. Also when driving on dirt roads it was rattling non-stop with the windows down.

 

Finally stuck my hand up there and noticed a bolt and nut were really loose. Tightened them up and no more noise.

[zicc]

Here is a good description I found on the noise that I am hearing. I am going to try to tie down the flapper valve to see if that fixes the issue.

 

When I press down on my accelerator I hear a rattling noise coming from somewhere under my truck, either the tranny or engine area, could be somewhere else on the driveline though. It sounds like a marble in a coffee can being shaken very quickly. It seems to only happen when the engine is catching up. I mean that as in if I let off the accelerator on the freeway then press it back down, it rattles until the engine goes back under strain. You know how there is kinda a soft spot until you actually start getting power to the wheels again, that's when.

[spiGini]

I have the same problem. Truck is at the dealer now for the 3rd day. Have to go in tomorrow to do a test ride with the technician to see if the sound they hear is the one I am talking about (even tho it is the only damn sound made). I told them I played with the adaptive valve while under the truck and it sounded like that was the issue but they are still sitting on the truck.

[zicc]

I found the valve and turned it a 1/4 turn and put a hose clamp around it to hold it in the open position. It seemed like the noise went away, but it was still there occasionally, so I can't say that that really made a difference. I took the hose clamp off and took it for another right and the noise was not there as often. I'm at a loss on this one. My wife took the truck to work today. I'll see what notices. Here is a picture of the valve, one without the clamp and the other with the clamp on.

 

I did notice that the noise only seemed to show up when in V4 mode, so it has to do something with that valve or that is just the engine making that noise when it is in V4 mode.