Grinding/ slightest vibration/ rpm bouncing

tlaw91 · February 2, 2020

Does the exhaust have the passive exhaust valve installed on it? Check to be sure. Some aftermarket ones do. Doesn’t have to be in V4 for it to happen when the spring gets weak.

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jpfanner · February 10, 2020

How do I check for the passive exhaust valve?

Chevys427 · March 18, 2021

Did you ever find the problem?

Michael Breeden · May 4, 2021

On 7/13/2018 at 10:58 PM, AllenW2018 said:

I’m going to describe this to the best of my ablitly, and see if anyone else has experienced this, or has any thoughts on it. Ive been riding like this for months because I haven’t had a chance to put it in the shop.

Truck: 2014 Sierra 1500 4x4 all terrain slt w/ 6.2. 4 inch lift. 33” tires. 20” wheels.

The sound: sounds like something rubbing/ slightly grinding. It has to be something rotating. It can be a faint noise or something loud that really grabs your attention.

When it occurs:

When everything starts warming up nicely, generally somewhere around 2 miles into trip. it’s by far the worst once you get to the speed you desire and stay there ( with cruise or just using pedal ). happens on occasion when accelerating up to speed, but not near as often. It never does it when slowing down.

Duration:

there is no pattern to it whatsoever. It could make the noise for .2 seconds. Stop for 12 seconds. Grind for 4 whole seconds. Stop for .5 seconds. You get the picture.

Its continuous, in a sense that if you have a 100 mile trip, it’s going to continuously start and stop the whole way.

Other things to note:

i have noticed that as soon as I hear the sound start, I can let off of the gas, or give it a little more and it immediately cuts the noise out. As soon as I hold the pedal and maintain speed, it starts back up.

The other her thing I’ve noticed is that the rpm needle is steadily moving at all times. Example, running 70 on perfect flat smooth road, cruise on, the rpm needle is Jumping back and forth about 100 rpms.

I have tried to be detailed and thorough, so let me know what you guys think if it sounds familiar.

I have the exact same thing. I've opened up the diff a couple of times and inspected for any obvious signs. Pulled both axles. Found seal leak on right rear. Replace seal, wheel bearing, and tone ring on right side. No fix. Closet video on YouTube I found that makes a similiar noise is from BurbBilly.

seansharley · September 2, 2021

On 5/4/2021 at 1:01 PM, Michael Breeden said:

I have the exact same thing. I've opened up the diff a couple of times and inspected for any obvious signs. Pulled both axles. Found seal leak on right rear. Replace seal, wheel bearing, and tone ring on right side. No fix. Closet video on YouTube I found that makes a similiar noise is from BurbBilly.

Has anyone resolved or found this? Same exact noise I’ve been chasing for over a year in my 14 6.2

onewheat · November 14, 2021

I have what sounds like the same issue on my '14 w/6.2. Mine is metallic - sounds like a heat shield vibe but the RPMs change while it is happening, so that makes me think it is rotational. I just pulled my driveshaft and checked U-joints and they seem solid and free. I have been fighting this since new - they exhaust was replaced twice under warranty as the dealer told me it was the flapper valve. There is a way to open the valve, slip a bolt in between the rotating part and the welded on part - this didn't affect it. I replaced the exhaust with a Corsa cat-back and I still hear it. It has gone from occasionally to very frequently over the last 7 years. It is just when cruising or lightly accelerating - no throttle or moderate/heavy throttle will immediately stop the noise. I honestly think it is driveshaft vibration or resonance. Unfortunately, I don't have any way to check that myself without just replacing the driveshaft, which is not a cheap way to 'check' a theory.

dslab · December 9, 2022

I've had same prob with my 14 sierra sounds like going over rumble straps. Did anyone ever find a fix?

onewheat · April 3, 2023

On 11/14/2021 at 12:40 AM, onewheat said:

I have what sounds like the same issue on my '14 w/6.2. Mine is metallic - sounds like a heat shield vibe but the RPMs change while it is happening, so that makes me think it is rotational. I just pulled my driveshaft and checked U-joints and they seem solid and free. I have been fighting this since new - they exhaust was replaced twice under warranty as the dealer told me it was the flapper valve. There is a way to open the valve, slip a bolt in between the rotating part and the welded on part - this didn't affect it. I replaced the exhaust with a Corsa cat-back and I still hear it. It has gone from occasionally to very frequently over the last 7 years. It is just when cruising or lightly accelerating - no throttle or moderate/heavy throttle will immediately stop the noise. I honestly think it is driveshaft vibration or resonance. Unfortunately, I don't have any way to check that myself without just replacing the driveshaft, which is not a cheap way to 'check' a theory.

I do realize that this post is older - all the noise I experienced turned out to be the torque converter. I would have never guessed that based on the sound - but a trans rebuild and new TC completely cured the noise. One test drive with the owner of the transmission shop so I could demonstrate the noise and he immediately said - 'Yeah, that's the converter' - he had another just like it in the lot doing the same thing.

Scotts H-D · October 23, 2024

I have a 2012 2500 hd in the shop doing the same thing. I hate to tell the customer he needs a transmission. He just bought it.
Has anyone else had any different results with the fix ?

How long do they go like this?

Scotts H-D · November 21, 2024

turns out it's the torque converter

BraydenH · December 1, 2024

On 7/13/2018 at 9:58 PM, AllenW2018 said:

I’m going to describe this to the best of my ablitly, and see if anyone else has experienced this, or has any thoughts on it. Ive been riding like this for months because I haven’t had a chance to put it in the shop.

Truck: 2014 Sierra 1500 4x4 all terrain slt w/ 6.2. 4 inch lift. 33” tires. 20” wheels.

The sound: sounds like something rubbing/ slightly grinding. It has to be something rotating. It can be a faint noise or something loud that really grabs your attention.

When it occurs:

When everything starts warming up nicely, generally somewhere around 2 miles into trip. it’s by far the worst once you get to the speed you desire and stay there ( with cruise or just using pedal ). happens on occasion when accelerating up to speed, but not near as often. It never does it when slowing down.

Duration:

there is no pattern to it whatsoever. It could make the noise for .2 seconds. Stop for 12 seconds. Grind for 4 whole seconds. Stop for .5 seconds. You get the picture.

Its continuous, in a sense that if you have a 100 mile trip, it’s going to continuously start and stop the whole way.

Other things to note:

i have noticed that as soon as I hear the sound start, I can let off of the gas, or give it a little more and it immediately cuts the noise out. As soon as I hold the pedal and maintain speed, it starts back up.

The other her thing I’ve noticed is that the rpm needle is steadily moving at all times. Example, running 70 on perfect flat smooth road, cruise on, the rpm needle is Jumping back and forth about 100 rpms.

I have tried to be detailed and thorough, so let me know what you guys think if it sounds familiar.

I’m no expert by any means but sounds like it may be a torque converter shudder. I’m actually here to try to get advice on my truck doing something like yours is. I don’t have any grinding but the fluctuating rpm’s and on and off kinda thing sounds like mine. If you shift to manual instead of drive and leave the rpm’s slightly higher then they’d normally be or drive in 1 gear lower then the truck automatically would does it go away?