Oli4

Yes. I checked my thermostat and looks like it was replaced.(see green dot). I have written letters to the dealership that did the rad replacement and waterneck to confirm. Which they did. I currently am also talking to GM customers service to see what's going on here. Because everything was correctly replaced according to the TSB. Waiting for a callback today. Once that is fixed I am flipping this truck. I AM BEYOND DONE.

Sorry to dig up this post. So maybe 6-12 months after I factory ordered my '14 Sierra All Terrain in Sept 2013, I had a rad leaking. So it was replaced by the dealership at no cost and I got the 'special Coverage 15829'. After this rad, the thing leaked 3 more times and has always been replaced since I was under warranty. I am currently on radiator no5! This one was installed at the end of June (at my cost because I am long out of warranty). Guess what. Leaking again! I want this truck to explode. I HATE THIS THING SO MUCH. Thanks GM for building a shitty product.

Here's what mine looks like. LOOKS LIKE JUNK. I bought this truck beginning of October 2013. So about 19 months old now. 2014 GMC Sierra All Terrain. As somebody who works FOR a company that does the marketing for GM, I am starting to get VERY sceptical when GMC is launching slogans like "Precision Truck Event" and "GMC, Precision Matters", etc. Look at my shocks for example! Seriously?!

Yesterday I noticed that some paint had come off my 6" round steps. I have heavy duty mud flaps. Now when I bought the truck, a 2014 Sierra All Terrain, I was very particular about having 'the least amount of chrome possible'. That's the reason why I went with the OEM black side steps (a friend had recomended against going aftermarket). I'm dissapointed that 18 months after I got the truck, these steps are already looking like crap because (as you can see in pic 2) paint adhesion isn't that great. There's bubbling visible and I am worried another big chip is coming off soon. And after next winter, all I will be left are some ugly rusted out side steps. Is this covered under waranty? Does anybody knows?

Well. My hum came back after about 2-3000 km. Not happy.

GUYS! MY TRUCK IS FIXED! Dealership replaced: 1 Pinion Bearing #15286375 1 Bearing #9413427 2 Differential Side Gear Bearings #20997053 1 Seal (frt diff drv p/gr) #12471590 1 Spacer #12479162 2 Gaskets #15270969 and #15270970 1 Adjuster #15876533 1 Seal #22761722 And of course filled it back up with synthetic gear lube. The tech's comment was: removed the front diff and inspected it. Upon inspection, discovered scored bearings on the carrier side of the diff. Overhauled and replaced front diff bearings. Test drive ok. Truck is quiet! FINALLY!!! I had forgotten how that felt. Funny how a bearing can completely ruin the experience you have with a vehicle. This is now a new truck and I am falling in love all over. Fingers crossed the scored bearing wasn't a result of something else...

There is no logic in that. I'll tell you why. Why is GM building the 'quietist cab ever' then? To fill it up with 'normal operating noises'?! http://www.ispot.tv/ad/72aZ/2014-chevrolet-silverado-quiet-cab

Bear with me gm-guy. What if: The front driveshaft u joint phase is slightly off. There's play in it. Essentially that play is wearing out the planet gear in the diff and that is creating that hum. The hum is when the planet gear teeth 'grind' or bind because driveshaft slows down (see vid) but diff wants to keep constant speed because of the wheels turning obviously. But when 4x4 gets activated. The u joints get loaded up and angles and phase line up to proper spec. So. Changing the diff will not change anything. It's the phase of the joints that needs to change. Bear with me gm-guy. What if: The front driveshaft u joint phase is slightly off. There's play in it. Essentially that play is wearing out the planet gear in the diff and that is creating that hum. The hum is when the planet gear teeth 'grind' or bind because driveshaft slows down (see vid) but diff wants to keep constant speed because of the wheels turning obviously. But when 4x4 gets activated. The u joints get loaded up and angles and phase line up to proper spec. So. Changing the diff will not change anything. It's the phase of the joints that needs to change.

Hmmmmmm Drive shaft phasing.... Check this.

UPDATE 2 Service foreman replicated the problem numerous times this morning and is now waiting to hear back from the GM technical advisor to see if there's any previous cases. SO the case # that was noted in this tread earlier on SHOULD pop up. FIngers crossed on that. They are keeping the truck and are adding chassis ears to the mix to try and diagnose the issue. But his suspicious is front driveshaft is not fully disengaging from the transfercase or drifeshaft is rotating freely because of something in front diff. Or something like that.

UPDATE The service tech at Hildebrandt Motors in Olds, AB was fantastic this morning. Super helpful and concerned. They wrote down my observations in my file again (after they read the notes from the first service back to me). And they requested if the service foreman could have the truck for a day to try to diagnose the issue. It seems like they are willing to help and to rectify the issue. Last time they contacted a GM tech and he said it was a 'normal operating' noise. But they are starting to doubt that. Fingers crossed. Oh and I also had a leaking radiator (never found a puddle in my garage though). But it's covered under warranty so they can replace it. ;) I now drive a 2014 Impala V6. It feels weird driving a car again. I'll keep you posted what the verdict is.

I have 45000km right now and the noise is gradually becoming worse. While driving the other day I noticed this. I've never noticed the pitch of the noise change before. At slow speeds 95kmh the noise is low pitched. At 105 it's a 'singing noise'. And at 115 it's more of a whine. Got me thinking. What turns that slowly in the drivetrain. I indeed came to the same answer as the previous person. Ring and pinion. I go in for service today. Going to give them an update. Can somebody from gm acknowledge on here that trucks with 4x4 and 3.73 gears have an issue? I believe that is the consensus right?

Don't think my problem is a bearing or a mirror. Sounds exactly like what GM-GUY is thinking it it. Incorrect wear of the gears and then the driveshaft starts to show so lateral play and it literally moves up and down and creating this harmonic noise. IT IS FRUSTRATING ME LIKE NOTHING BEFORE. C'mon GM do something here.

I wonder when GM is actually going to acknowledge that this IS an issue...

I'm 27000km in and the noise is still there. My dealership made a note of it in my file plus has documented and verified the sound as well. So it's not hear say from me. They also road tested another vehicle and it had it too. IMO this is NOT normal road/trans noise. This is a harmonic. It might be harmless it might not. All I can tell it still annoys the crap out of me. I'm like you at this point. I'm waiting for it to break on me.

Here's an update from the Canadian side of the border. I went in for my first oil change this morning. I talked about the noise with my service department. They took the truck out for a spin and the tech heard the same noise as I did (yay I'm not loosing it). He came back, took another truck out for a spin (I assume another 5.3L). Same thing. It had the same noise. He then called GM (I assume GM Canada) but there they had not heard of the issue as of yet. The tech acknowledged the noise and called it a 'normal operating noise' (he even did the air quotes). The issue is now documented in my paperwork but as of now they don't want to throw parts at it. They asked me to monitor it and call them when it gets worse.

So you're saying it is still there? After they replaced the drive shaft? Almost going in for my first service.

Same here. But. Here's an update. It goes away when trans temps reach normal operating temperatures 90C. Did a long trip over the weekend and it went away. It's back now though.

It is not a vibration. I can't feel it in my steering wheel or in my butt. ;) It's just a noise 1kwik72.

1kwik72 That's exactly what I though too. That it was a harmonic from something vibrating. But yes it is high speed only. But 30-35mph is about HALF of the speed I am getting it at (65mph). If this is a vibration then it will naturally occur at different frequencies too. Maybe that's what I am experiencing. Your thoughts? I'm glad I'm not the only one though Boot. I thought I was loosing my mind.

Update on the humming noise. If I shift it to 4x4 auto, the noise disappears. If I shift it back to 2x4 noise gradually comes back.

Sound happens under power and while coasting. Doesn't matter what gear I am in. Goes like this. XXXXXXXX__________XXXXXXX________XXXXXXXX________XXXXXXXX XXXX=hum and lasts about 1 sec with 1sec pauses in between. Really weird.

Hi all New member here from Canada. A month and a half ago I took possession of a brand new, factory ordered 2014 Sierra All Terrain. Fantastic ride. There's one thing that concerns me though. And I really don't have an idea what it can be. But this engine makes a rhythmic humming noise when driving at highway speeds (105km/h, sorry we are metric). Humming lasts for 1 sec and then 1 sec of silence, 1 sec of humming, 1 sec silence and so on. Doesn't matter on or off the power, or in v4 or v8 mode. So it's speed related not rpm related. Goes away when slowing down and cross the 95km/h mark or so. I've tried pretty much everything. Even turned airco off thinking it might could have been the fan. No dice. It's subtle but the wife picked up on it too. So what could this be? Any ideas? Looking fwd to every suggestion I get on this forum. Thank you.