issue Humming/Whining noise between 40 and 50 MPH?

[Yffreh26]

Recently picked up my 2014 Sierra 6.2, Max Tow and it's awesome!

 

One thing I noticed is that the cab is REALLy quiet compared to previous versions, except for this noise that starts softly around 35, then as you approach 50 gets louder, then goes away. It's the loudest under power, but still faintly there even while coasting at those speeds.

 

I have already had it back to the dealer, and they have originally thought that it was bad bearings in the rear end (3.73), so they were replaced. They told me all was good, but I don't think the tech actually drove the right speed to test the issue. It's not SUPER loud, but with the radio at a basic volume, you can hear the tone of this noise right through the radio.

 

Service manager and I went out in a 5.3 with 3.42 rear end, and didn't hear anything but I didn't think it was a good test given the entirely different engine, driveline and rear end that I have. There are no other 6.2 max tow's close to where I am to test this out so I am hoping someone can tell me if this is normal, or not.

 

Thanks!

 

 

[DRS 95 Silverado]

http://www.gm-trucks.com/forums/topic/157796-vibration-in-floorboard-not-speedtire-related/

 

Look at this post.

[Yffreh26]

Thanks DRS! That sounds like it's on the right path...I don't have any vibration issues at all, it's just a noise.

[JCT404]

I've got the same sound, comes on around 55 and goes away around 70, sound just like a ring and pinion the way it growls in and out, although I doubt it's the rear end. It not very load but is noticeable...taking it in this week to have it looked at, its a 5.3 with 3.42's

[DRS 95 Silverado]

I've got the same sound, comes on around 55 and goes away around 70, sound just like a ring and pinion the way it growls in and out, although I doubt it's the rear end. It not very load but is noticeable...taking it in this week to have it looked at, its a 5.3 with 3.42's

 

Thats what mine is.

[pm26]

I recommend at least inspecting the rear differential gears/bearings on those trucks.

[Yffreh26]

pm26, gears were already replaced at the dealer with no change to the noise or symptoms.

[pm26]

pm26, gears were already replaced at the dealer with no change to the noise or symptoms.

They may have replaced the gears, but have they checked/set the gear backlash correctly? Proper shimming of gears is essential to preventing these noises. After you open the differential, you can measure the pinion/ring gear backlash to check whether it is in spec. I have a feeling that these people are just randomly replacing parts because they have no idea what is wrong. These trucks are simply too new to cause any appreciable wear on the differential gears, even if the gears were shimmed completely worng. If you have vibration in your truck due to improperly balanced tires, you can replace the tires with the best tires there are, but if you do not balance them correctly, you will still have the same vibration problem. The same principle applies to differentials - replacing parts without properly adjusting them will not cure the problems.

[GMCustomerService]

Hi Yffreh26,

 

I’m sorry to hear that you are experiencing noises coming from your vehicle while driving. I understand that your concern has not been resolved after taking your vehicle to the dealership. I would like to take an extra look into your concern. Please private message your full name, address, current mileage, VIN, and the involved dealership if I can be of any assistance. Thank you.

 

Kristen A.

GM Customer Care

[Yffreh26]

Well, it's back in the shop again. Backlash was correct, and it was still making the same noise. They are replacing pinion gear now, and of course it's on backorder. Maybe tomorrow or Monday to get it back. Driving a lovely Buick in the mean time. Very frustrating to have a truck with less than 700 miles on it in the shop already twice!

[pm26]

Well, it's back in the shop again. Backlash was correct, and it was still making the same noise. They are replacing pinion gear now, and of course it's on backorder. Maybe tomorrow or Monday to get it back. Driving a lovely Buick in the mean time. Very frustrating to have a truck with less than 700 miles on it in the shop already twice!

I would also replace the pinion shaft bearings.

[Yffreh26]

So I got it back, with the pinion shaft bearings now replaced, and the noise is more subtle but still there. It's actually louder ABOVE 50mph, where before it was gone there. Dealer isn't sure what to do next, but I am tired of bringing this in. Anyone have any other ideas?

[pm26]

Nissan had similar problems with their trucks in the mid 90s. Some differentials were making whining noise when under load, some while coasting only. The root cuase was determined to be less than optimal gear backlash setting. Nissan claimed that this had no impact on longevity of the differential and recommended thicker (higher viscosity) gear oil to quiet down noisy differentials.

 

I still suspect that tyou have a gear backlash issue causing the whining/humming noise.

 

I would request a new rear axle assembly if they cannot find the problem.

[Yffreh26]

That sounds like what they are going to do next. After the pinion was replaced, it was different, but not better. Noises all over the speed map now whereas before, it was very specifically at one particular range.

 

This is getting nutz. Only 700 miles on the truck, and it's going in for the third time. It's been in the shop more than I have had it!

[klrrdr]

I had a whining sound the first 2 times out. The third time I left her home