question: There's a faint chattering noise when accelerating on th

Sean Neilan · December 10, 2016

My '15 does it randomly but it goes away if I turn off the climate fan. Def changes tempo with throttle and all that. I'm wondering if it's only audible when the vent doors are in certain positions.

Dnt · December 10, 2016

I have the chatter on my 2016 Denali 6.2 8spd 3.23 rear end but only under very specific conditions as follows.

1. Engine has to be in V4 mode

2. Speed has to be between 55 and 60MPH

3. RPM has to be between 1200 and 1300RPM

4. Have to be traveling on a flat road and the V4 has kicked in then the road has a slight rise as i give it just a very little throttle (NOT ENOUGH TO CHANGE TO V8 mode) the engine seems to bog just a little trying to stay in V4 mode then sometimes you can get the chatter. I have found that it takes a good bit of practice to make it do this.

5. Gas octane does not change it one bit I am currently running 87 octane as a test to see if that made it worse and it does not. I usually run 93 octane.

UTUBE link here. Note: I have the GM Borla exhaust installed so it is hard to hear but just turn it up and you can hear the metallic chatter. It sounds like the valvetrain or a lifter to me! It is just so rare and hard to get it to do it that I know the dealer will never find it. I guess it is up to us to do some research and try to get some good video and data. My guess is that it is the valvetrain and has something to do with the AFM system?................pretty sure that we will start seeing a lot of valvetrain failures as the miles are racked up on these late model engines. no way it will last making that kind of metallic racket! It would be real nice to catch it early (GM ARE YOU LISTENING) so that we do not have to go through all that crap and expense.

https://www.youtube.com/watch?v=UIxJ_5mrmCQ

Pacfanweb · December 11, 2016

We don't have 89 octane here in Oregon/Washington. We have 87 and 93. No mid-grade.

hmm, I haven't put in premium fuel just because of that. I'm glad you're experiencing it as well and not just me. Thanks for the insight.

So mix premium and regular. That's all mid-grade is anyway.

Probably not the issue anyway.

Not sure I'm hearing the chatter in these videos. I guess that means if I don't recognize it, mine must not have it?

Edited December 11, 2016 by Pacfanweb

congden · December 28, 2016

I have the chatter on my 2016 Denali 6.2 8spd 3.23 rear end but only under very specific conditions as follows.

1. Engine has to be in V4 mode

2. Speed has to be between 55 and 60MPH

3. RPM has to be between 1200 and 1300RPM

4. Have to be traveling on a flat road and the V4 has kicked in then the road has a slight rise as i give it just a very little throttle (NOT ENOUGH TO CHANGE TO V8 mode) the engine seems to bog just a little trying to stay in V4 mode then sometimes you can get the chatter. I have found that it takes a good bit of practice to make it do this.

5. Gas octane does not change it one bit I am currently running 87 octane as a test to see if that made it worse and it does not. I usually run 93 octane.

UTUBE link here. Note: I have the GM Borla exhaust installed so it is hard to hear but just turn it up and you can hear the metallic chatter. It sounds like the valvetrain or a lifter to me! It is just so rare and hard to get it to do it that I know the dealer will never find it. I guess it is up to us to do some research and try to get some good video and data. My guess is that it is the valvetrain and has something to do with the AFM system?................pretty sure that we will start seeing a lot of valvetrain failures as the miles are racked up on these late model engines. no way it will last making that kind of metallic racket! It would be real nice to catch it early (GM ARE YOU LISTENING) so that we do not have to go through all that crap and expense.

https://www.youtube.com/watch?v=UIxJ_5mrmCQ

I can sort of hear what your talking about in the video, my 16 5.3 makes a similar sound with the conditions you described, mine sounds like there are some metal chunks rolling through the exhaust or inside of a tin can. I usually get this as well in a high gear low RPM condition on flat surfaces while accelerating.

Edited December 30, 2016 by congden

mdreynolds · February 26, 2017

I just purchased a new 2016 Silverado, I've had it for 5 days and now have 195 miles on it, Anyway, On acceleration or coasting around 15mph to 35mph, it sounds like the chattering of a U Joint, like someone said "Card In a bicycle wheel", goes up and down with speed, put it in neutral while coasting and it goes away, so whatever it is it does its under a load, comes from beneath drivers side towards the rear.

Jeff5347 · February 26, 2017

I don't know if anyone has stated this yet but I had a similar problem on my 15 Lt. Bought it in Dec of 2015 and after a few hundred miles I heard this scraping grinding kind of noise. Only on light steady throttle at around the 25-30 mph mark and in v4 mode. If I got into it it would go away. Lived w it for a few weeks trying to figure out what it was so I called the dealer and they took it in to listen to it. It turned out to be the flapper valve. They replaced it and it never appeared again

Sent from my Nexus 6P using Tapatalk

Edited February 26, 2017 by Jeff5347

XSKIER · February 26, 2017

This makes more sense to me rather than water pumps, fuel pumps, injectors, or valvetrain. Happy to hear that you are fixed!

Donstar · February 26, 2017

I just purchased a new 2016 Silverado, I've had it for 5 days and now have 195 miles on it, Anyway, On acceleration or coasting around 15mph to 35mph, it sounds like the chattering of a U Joint, like someone said "Card In a bicycle wheel", goes up and down with speed, put it in neutral while coasting and it goes away, so whatever it is it does its under a load, comes from beneath drivers side towards the rear.

Go with your dealer's service adviser or the assigned technician for a ride and let him/her hear the chattering. Your truck is brand new and needs to run flawlessly!

Skeeter McSkeet · February 26, 2017

I don't know if anyone has stated this yet but I had a similar problem on my 15 Lt. Bought it in Dec of 2015 and after a few hundred miles I heard this scraping grinding kind of noise. Only on light steady throttle at around the 25-30 mph mark and in v4 mode. If I got into it it would go away. Lived w it for a few weeks trying to figure out what it was so I called the dealer and they took it in to listen to it. It turned out to be the flapper valve. They replaced it and it never appeared again

Sent from my Nexus 6P using Tapatalk

My flapper put out a high pitch squeak sound when it would go from v4 to v8, it got louder and louder as time passed. A lot of guys remove it or pin it open. I got a tuner and turned afm off, no more flapper to listen to.

The ticks from the driver side don't seem to be as frequent as they had been prior to the tuner.

Sent from my kayak

dlang13 · February 27, 2017

I have read about a few different guys running different octanes and it not helping. I never noticed if it was because of the AC or not. Im going to test that tonight. I did read one case where a guy had his water coolant pump replaced and said that fixed it.

should i not e running the lowest octane in my truck? i always have with all my vehicles.

Starting running mid grade in my 15 after always running the lowest and I've noticed a significant difference in power.

Even the miss's has said it has more power since using higher grade.

Does cost about $10-$15 more dollars per fill but well worth it IMO.

Also have noticed the "ticking sound" isn't as noticeable while running the higher octane. I was told from the dealer that this was normal. Sound reminds me a small exhaust leak i once had on an older vehicle.......

Glad others are having the same issue.......

mdreynolds · March 17, 2017

Go with your dealer's service adviser or the assigned technician for a ride and let him/her hear the chattering. Your truck is brand new and needs to run flawlessly!

There was a large stick stuck between the driveshaft and the cab. LOL, truck was 7 days old when I took it in to dealer, hard the noise from day one.

Donstar · March 17, 2017

There was a large stick stuck between the driveshaft and the cab. LOL, truck was 7 days old when I took it in to dealer, hard the noise from day one.

That is hilarious! It is fun going back to read the other comments relating to the op's concern. Diagnosis over the internet can certainly lead you in the wrong direction! The solution to his issue may not be as simple as yours but your outcome demonstrates the need for him to take his vehicle in for service.

phabejhmoob · March 17, 2017

I have the chatter on my 2016 Denali 6.2 8spd 3.23 rear end but only under very specific conditions as follows.

1. Engine has to be in V4 mode

2. Speed has to be between 55 and 60MPH

3. RPM has to be between 1200 and 1300RPM

4. Have to be traveling on a flat road and the V4 has kicked in then the road has a slight rise as i give it just a very little throttle (NOT ENOUGH TO CHANGE TO V8 mode) the engine seems to bog just a little trying to stay in V4 mode then sometimes you can get the chatter. I have found that it takes a good bit of practice to make it do this.

5. Gas octane does not change it one bit I am currently running 87 octane as a test to see if that made it worse and it does not. I usually run 93 octane.

UTUBE link here. Note: I have the GM Borla exhaust installed so it is hard to hear but just turn it up and you can hear the metallic chatter. It sounds like the valvetrain or a lifter to me! It is just so rare and hard to get it to do it that I know the dealer will never find it. I guess it is up to us to do some research and try to get some good video and data. My guess is that it is the valvetrain and has something to do with the AFM system?................pretty sure that we will start seeing a lot of valvetrain failures as the miles are racked up on these late model engines. no way it will last making that kind of metallic racket! It would be real nice to catch it early (GM ARE YOU LISTENING) so that we do not have to go through all that crap and expense.

https://www.youtube.com/watch?v=UIxJ_5mrmCQ

Thanks for the video - this is exactly the sound I am experiencing. my truck now has 11300 miles and still the same (occurs only at times).

Starting running mid grade in my 15 after always running the lowest and I've noticed a significant difference in power.

Even the miss's has said it has more power since using higher grade.

Does cost about $10-$15 more dollars per fill but well worth it IMO.

Also have noticed the "ticking sound" isn't as noticeable while running the higher octane. I was told from the dealer that this was normal. Sound reminds me a small exhaust leak i once had on an older vehicle.......

Glad others are having the same issue.......

I haven't tried higher octane yet, maybe I will when I get to half tank. You are correct about the older vehicles exhaust leak. A long time ago my mom use to own a Chevy Astro van and it made the same sound going up hill.

That is hilarious! It is fun going back to read the other comments relating to the op's concern. Diagnosis over the internet can certainly lead you in the wrong direction! The solution to his issue may not be as simple as yours but your outcome demonstrates the need for him to take his vehicle in for service.

well, the dealership insists it's normal. Unless they can see something obviously wrong, i highly doubt they will try to fix it. It's more of an annoyance than anything else.

scannylada · March 18, 2017

I have a 2017 sierra cc 6.2L gm borla exhaust. At about 400 miles I started to have the driving over rumble strips feeling at the same time as described above when you get your ticking sound. By the time I hit 3400 mi. I couldn't take it. Was almost embarrassing. Took it to dealer and they followed tech bulletin and flushed transmission 3 times. Got the truck back and the rumble strip shake is gone but now I have the tick at the exact same point that the rumble would happen.

I thought the same things. Tried 93 gas in case dealer put in 87 since they put 250 mi on truck trying to simulate and confirm problem was fixed. Thought it might be exhaust leak but no signs of one. Have thought at times it might sound like a fluid rushing sound (something with the trans). Have thought about it being the flapper. Was going to try and prop it full open (waiting for weather to warm up a little). The fuel pump and or injectors could makes sense too