New here! 6.0 question

Jonquist5 · December 3, 2017

Hey guys, brand new to the forum here. I just recently picked up a 2015 Sierra 2500HD, 52k miles on it. 6.0 gas job. I noticed recently what seems to be a loud whirring noise coming from the front end, only on deceleration, above 40mph. As soon as you step back on the gas, it disappears. Back off the gas, reappears. It almost sounds like a bad tire howling. Tires are brand new on all 4 corners, installed at the dealer with a fresh alignment. I brought it back to the dealership to have them try and pinpoint the noise. They stated it is a flapper valve in the exhaust opening/closing. I can't find anything at all about the 6.0's having a flapper valve, and was hoping you guys could steer me in the right direction. Thanks!

grizzlyltz · December 3, 2017

Your right! 2500hd do not have a flapper
Are you in 4 wheel drive?

Grizzly

Jonquist5 · December 3, 2017

2 hours ago, grizzlyltz said:

Your right! 2500hd do not have a flapper
Are you in 4 wheel drive?

Grizzly

I am not. Haven’t touched the 4wd at all yet actually. Glad I was at least right about there not being a flapper valve as they keep insisting

2016HD · December 3, 2017

Absolutely nothing in the exhaust system!! It sounds like maybe you have a bad hub assembly/wheel bearing? Or you should get the front Differential checked? Possibly under filled from the factory and now there is a bearing going. Are you sure its from the front of the truck?

Jonquist5 · December 3, 2017

2 hours ago, 2016HD said:

Absolutely nothing in the exhaust system!! It sounds like maybe you have a bad hub assembly/wheel bearing? Or you should get the front Differential checked? Possibly under filled from the factory and now there is a bearing going. Are you sure its from the front of the truck?

Positive it’s coming from the front of the truck, specifically the drivers side. I initially wrote off a bearing since I’ve had them go before and it’s a more constant sound, but will have them look at everything when I bring the truck back this week

4wdriver · December 4, 2017

Hopefully you can find a place to take it where they don’t make up parts to blame noises on. Some camaros have a valve in the exhaust.

redwngr · December 4, 2017

19 hours ago, 4wdriver said:

Hopefully you can find a place to take it where they don’t make up parts to blame noises on. Some camaros have a valve in the exhaust.

1500's have a valve in the exhaust as part of the AFM.

HD's don't have AFM and don't have the flapper valve.

4wdriver · December 4, 2017

2 hours ago, redwngr said:

1500's have a valve in the exhaust as part of the AFM.

HD's don't have AFM and don't have the flapper valve.

Thanks for that FYI. I hadn’t heard of that valve. I do like to know a lot about trucks sort of a hobby I guess. No real experience with afm except a loaner. Do you know if there is any truth to the statement they made to the op about the valve being the cause of his noise problem?

crankman · December 4, 2017

That does sound like your in 4 hi. That is the same sound my 15 makes in 4hi. But you would notice it making turns.

redwngr · December 5, 2017

41 minutes ago, 4wdriver said:

Thanks for that FYI. I hadn’t heard of that valve. I do like to know a lot about trucks sort of a hobby I guess. No real experience with afm except a loaner. Do you know if there is any truth to the statement they made to the op about the valve being the cause of his noise problem?

The 6.0 (which is only in the HD trucks, and doesn't have AFM,) does not have the valve -- so it can't be the source of the OP's noise.

4wdriver · December 5, 2017

45 minutes ago, redwngr said:

The 6.0 (which is only in the HD trucks, and doesn't have AFM,) does not have the valve -- so it can't be the source of the OP's noise.

Wow I really suck at being observant today. Usually I’m the one pointing out the obvious. Thanks again. I’m gonna stop posting now till I wake up.

Jonquist5 · December 5, 2017

13 hours ago, crankman said:

That does sound like your in 4 hi. That is the same sound my 15 makes in 4hi. But you would notice it making turns.

I put the truck into 4 hi this morning on my way to work. No change in the noise. It’s definitely not stuck in 4 hi though, like you said you’ll obviously feel it in turns.

Truck is going back to the dealer tonight so hopefully I’ll have an update soon. Thanks for all the suggestions so far everyone!

Jonquist5 · December 7, 2017

So far they’ve looked at the brakes and hub assemblies up front. They’re starting with the front diff today. At least they’re not denying there’s something going on with it now

XSKIER · December 10, 2017

How about a broken motor mount? Fan rubbing the shroud? Transfer Case chain loose? Exhaust heat shield or muffler innard loose and rattling?

Sent from my SM-G930V using Tapatalk

Jonquist5 · December 10, 2017

Got the truck back the other day. They told me no issues found anywhere. Transfer case and trans good. Told me it’s potentially tire noise. Just had a snow storm yesterday, put it in 4hi again; noise disappeared! Back in 2wd, noise starts back up. Switched it a few times to confirm. Hmmmm