drivetrain grinding noise

MNStroker316 · Feb 14, 2016

Hey guys,
My truck has recently developed this noise that sounds like a tire rubbing a fender liner or even a wheel bearing (for lack of a better description). Sound is the same in 2wd and 4wd.
The sound is directly proportional to the speed of the tires, can hear it from 20MPH and up. Slowing down, coasting, and accelerating. Sound does not change turning left or right (taking front wheel bearings out of the question i would think). Its very difficult to tell what direction it is coming from.

Changed the fluid in the front and rear axles (they needed it anyways) the Diffs both looked in good condition, no metal in oil or anything.
Checked out all 4 wheel bearings, no play, no grinding when turning by hand.(Also put a stethoscope to them, no odd sounds)
Front axles both have new ujoints (also did all ball joints) about 10k ago.

Dropped the driveshaft. No play in rear drive shaft u joint and the center bearing turned smooth. Took it for a drive with no driveshaft, in 4wd, and the noise still persisted.
Put the truck on a lift and ran it up to about 30mph, could not replicate the noise.

The unknowns I have left
Tcase- fluid looks good, but what kind of sounds would a bad tcase make?
Trans- Shifts as it always has, Fluid looks good
Tire noise? gonna throw a different set on this week hopefully to test this theory, even though it doesn't sound like tire noise to me since it happens on all ground (snow, dirt, pavement, etc.)
Maybe I missed something in the differential? Bad pinion bearing?.
Was also considering taking the front wheel bearings off to better inspect them by hand. But that wouldnt be for a couple weekends.

What am I missing? This sound is driving me bananas!

Thanks for the help.

DEEZUZ · Feb 14, 2016

Rear parking brake shoes worn?

MNStroker316 · Feb 14, 2016

Ya know, you're the second person to mention that, I forgot to look at the e brake when I had it up this weekend. Only reason it wasn't on top of the list to check is because the truck got new rear breaks about 20k ago.
I had the rear axle shafts out and was spinning each wheel on its own (trying to check the rear wheel bearing) and didn't hear any sounds, but I probably should just take the tire off and examine the e brake.

junglejoe · Feb 15, 2016

The front wheel bearings do not have to have play in them for them to be bad. been there done that!

MNStroker316 · Feb 16, 2016

junglejoe said:
The front wheel bearings do not have to have play in them for them to be bad. been there done that!

So are you saying loading and unloading them (turning left and right) it would make no difference in sound and it was still a front wheel bearing ?

03_PSD · Feb 17, 2016

Have you jacked up the truck and turned the wheels by hand to see if you can hear anything or feel for binding?

MNStroker316 · Feb 17, 2016

03_PSD said:
Have you jacked up the truck and turned the wheels by hand to see if you can hear anything or feel for binding?

Yes I have. Did this with the front wheels, as well as the rear wheels (with axle shafts out). Didn't feel or hear any binding/grinding.
Had a friend do the same thing to make sure I wasn't missing anything. He Even took a stethoscope with a probe on it, to the front ones, said he didn't hear anything abnormal.

6.0 Tech · Feb 17, 2016

Try unbolting yhe driveshaft from the trans and run it up and see if yhere is any noise. Use a stehescope if yhere is to determine if t case or trans maybe...

MNStroker316 · Feb 18, 2016

Yeah I had the drive shaft out last weekend and drove it in 4wd. And the sound still persisted.
But I think this weekend we are gonna put it back on the lift and try running it up to 30-40mph, and put the scope on pretty much everything. That seems to be the next easiest option for diag.

dangerous1 · Feb 18, 2016

Does it make the sound in reverse?

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MNStroker316 · Feb 18, 2016

dangerous1 said:
Does it make the sound in reverse?

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I actually don't know that... The sound is roughly 20mph+ so I would have to find a safe place to test that. What direction would that point me? Away from the trans or something?

dangerous1 · Feb 18, 2016

MNStroker316 said:
I actually don't know that... The sound is roughly 20mph+ so I would have to find a safe place to test that. What direction would that point me? Away from the trans or something?

I honestly don't know. Was just curious.
Other thought was if you are lifting it by the axles or on the frame. If your lifting on the frame then the axles would be dropping. Just a thought.

jake74 · Feb 19, 2016

I usually lift the truck with my 2 post lift then lower it onto jack stands placed under the axles. I've found that if you don't do this it puts the driveshafts at a ****ty angle and can cause a vibration at higher speeds.

bluedge8 · Feb 20, 2016

MNStroker316 said:
So are you saying loading and unloading them (turning left and right) it would make no difference in sound and it was still a front wheel bearing ?

Front wheel bearings can present in a variety of ways. Turning left or right and making noise is most common, but they can have constant noise also. I had a wheel bearing in my yukon just randomly lock up and or make so much noise it sounded like metal to metal brake pads, that was fun. Where do you live again?

MNStroker316 · Feb 20, 2016

jake74 said:
I usually lift the truck with my 2 post lift then lower it onto jack stands placed under the axles. I've found that if you don't do this it puts the driveshafts at a ****ty angle and can cause a vibration at higher speeds.

I'll see if I can do this next week when I bring my truck into work, probably the best option to get the axles "loaded" to see if the I can find where the noise is coming from

MNStroker316 · Feb 20, 2016

bluedge8 said:
Front wheel bearings can present in a variety of ways. Turning left or right and making noise is most common, but they can have constant noise also. I had a wheel bearing in my yukon just randomly lock up and or make so much noise it sounded like metal to metal brake pads, that was fun. Where do you live again?

Yeah I think I'm gonna take the front wheels off, maybe even the whole hub to inspect them. I currently live in grand forks, ND for school. From the Saint Paul area.

bluedge8 · Feb 20, 2016

So the truck is in Grand Forks? let me know if you need a shop up that way, a buddy of mine lives in Hilsboro.

MNStroker316 · Feb 29, 2016

bluedge8 said:
So the truck is in Grand Forks? let me know if you need a shop up that way, a buddy of mine lives in Hilsboro.

Yes it is. Thank you! I will let you know if I'm ever in a pinch!

MNStroker316 · Feb 29, 2016

So I was able to look at the truck again this weekend. We threw it up on the lift and set cruise around 30mph and walked around and probed different spots. The rear wheel bearings had no irregular noise to them. The pinion bearing area was questionable, nothing too alarming (loud grinding, etc) and the tcase seemed fine, my mechanic buddy (GM tech) said it seemed kinda loud but he had nothing to compare it to.
But I am leaning towards the pinion bearing at this point since I'm out of other options, and it looks as if the pinion seal leaks a very small amount, or it has leaked in the past. So I'm unsure.