Transfer case or Front End whine/growl.

[Saucy_Walnuts]

That is nasty looking and could be close to normal if it was the first fluid change but if is still rounding off sharp edges this many miles down the road and fluid is original, I would clean it out completely and add new fluid and drive it to see what happens and if does quiet down, then change fluid again at 5k to 10k miles.

Plus, make sure you do the rear diff and the transfer case.

Noise did not change much maybe 20% less. Tcase was serviced as well tonight. Could not do the rear diff waiting on a gasket. Need to pick it up this weekend. As far as I know it's the first service ever on the front diff. Or any of the the drive train besides the engine oil. It's got 177k on it. All Ujoints are original as far as I can tell. They will be next on my list.

 

[OR VietVet]

That noise may go away after more miles with new fluid. Or need to change again. Did you clean/flush it out when drained?

 

[strutaeng]

Yikes. That doesn't look good at all.

Maybe a remanufactured front differential is a wise idea. Just make sure you get the correct gear ratio.

I wonder if you can isolate the noise to confirm (not that the photo with the metal shards isn't enough proof), like driving it without the front driveshaft? IDK...

Please keep us posted on outcome.

 

[vcode]

How about the front differential? My truck is AWD, but I had a growl in the front end, and when the mechanic put it on the lift with a person inside operating the shifter and throttle, the mechanic used his stethoscope to pinpoint the source of the issue -> front differential was shot.

Common issue. My 2010 was shot at 50K miles. Might even be TSB put there?

 

[West 1]

I have a 2008 Denali with a whine in the drivetrain. It is not bad but I know I have a bearing somewhere going south. I have yet to determine where it is coming from. I have put it on Jack stands and ran it in gear while crawling under with a stethoscope trying to find the guilty bearing. So far I still don't know if it is Front or Rear, have not ruled out the transfer case. Unfortunately the Denali has full time 4x4 so lifting it on jack stands causes some drivetrain chatter and does not really allow spinning the axles at 50 mph to find the noise. I may end up pulling the driveshafts one at a time to see which eliminates the noise. Sometimes a sound will travel under your car and mask where it originates. Can be a pain to find. At this point I suspect it is a rear diff carrier or pinion bearing failing but still not willing to tear it down till I can really isolate the problem. I am open to any tricks that help show where the noise is.

I know I could leave it for another 30,000 miles while hoping it gets louder and I can find it but I like things to work properly and quietly. Already replaced all fluids, no change in noises.

 

[rockola1971]

I have a 2008 Denali with a whine in the drivetrain. It is not bad but I know I have a bearing somewhere going south. I have yet to determine where it is coming from. I have put it on Jack stands and ran it in gear while crawling under with a stethoscope trying to find the guilty bearing. So far I still don't know if it is Front or Rear, have not ruled out the transfer case. Unfortunately the Denali has full time 4x4 so lifting it on jack stands causes some drivetrain chatter and does not really allow spinning the axles at 50 mph to find the noise. I may end up pulling the driveshafts one at a time to see which eliminates the noise. Sometimes a sound will travel under your car and mask where it originates. Can be a pain to find. At this point I suspect it is a rear diff carrier or pinion bearing failing but still not willing to tear it down till I can really isolate the problem. I am open to any tricks that help show where the noise is.

I know I could leave it for another 30,000 miles while hoping it gets louder and I can find it but I like things to work properly and quietly. Already replaced all fluids, no change in noises.

Running a AWD off the ground is an excellent way to destroy the BW AWD unit. Removing a driveshaft and running it off the ground is an even more excellent way to destroy the BW AWD unit. Viscous couplers need love too.

Check the front hubs with wheels off ground.

 

[Saucy_Walnuts]

That noise may go away after more miles with new fluid. Or need to change again. Did you clean/flush it out when drained?

I did not, I used the cheapest oil I could find to do a flush. I planned on putting a few miles on it then rechange of the oil.

 

[Saucy_Walnuts]

Yikes. That doesn't look good at all.

Maybe a remanufactured front differential is a wise idea. Just make sure you get the correct gear ratio.

I wonder if you can isolate the noise to confirm (not that the photo with the metal shards isn't enough proof), like driving it without the front driveshaft? IDK...

Please keep us posted on outcome.

I planned on possibly removing the CV axles? If I can without damage and drive around the block.

 

[West 1]

Rockola, I have rebuilt a few of these transfer cases, I don’t see anything inside these that will blow up because I test it on jack stands. The speed sensors will notice the front wheels and rear are not going the same speed and set a code that is easily cleared once work is done.
Sometimes a noise can’t be isolated without a test like this.
Running the truck in gear on jack stands does cause the front diff to work the spider gears unusually hard and that makes odd noises, the CV shafts hanging low with the control arms fully down is not good for them either so I think I will repeat the test with the front driveline removed. If the rear end and transfer case end up quiet after this test I know it is the Front differential but I really hope not. I have never rebuilt one of the front diffs and do not want to learn that one.

Had one with 4.10 gears, was thinking of switching to 3.42 gears for better MPG. I installed a rear diff with 3.42’s and for this test removed the front driveshaft and drove it about 300 miles. MPG was basically the same and the vehicle felt slow off the line after running the 4.10 ratio fso I reinstalled the 4.10 gears. Had to clear the codes of course but no other issues. For my use I really liked the 4.10 gear ratio and would get one again.

 

[Fless]

Rockola, I have rebuilt a few of these transfer cases, I don’t see anything inside these that will blow up because I test it on jack stands. The speed sensors will notice the front wheels and rear are not going the same speed and set a code that is easily cleared once work is done.
Sometimes a noise can’t be isolated without a test like this.
Running the truck in gear on jack stands does cause the front diff to work the spider gears unusually hard and that makes odd noises, the CV shafts hanging low with the control arms fully down is not good for them either so I think I will repeat the test with the front driveline removed. If the rear end and transfer case end up quiet after this test I know it is the Front differential but I really hope not. I have never rebuilt one of the front diffs and do not want to learn that one.

Had one with 4.10 gears, was thinking of switching to 3.42 gears for better MPG. I installed a rear diff with 3.42’s and for this test removed the front driveshaft and drove it about 300 miles. MPG was basically the same and the vehicle felt slow off the line after running the 4.10 ratio fso I reinstalled the 4.10 gears. Had to clear the codes of course but no other issues. For my use I really liked the 4.10 gear ratio and would get one again.

If you want to be sure that @rockola1971 sees this, be sure to tag him like I did here (start with the "@" symbol and start typing a member's name). Otherwise he may not see that he was mentioned.

 

[rockola1971]

Rockola, I have rebuilt a few of these transfer cases, I don’t see anything inside these that will blow up because I test it on jack stands. The speed sensors will notice the front wheels and rear are not going the same speed and set a code that is easily cleared once work is done.
Sometimes a noise can’t be isolated without a test like this.
Running the truck in gear on jack stands does cause the front diff to work the spider gears unusually hard and that makes odd noises, the CV shafts hanging low with the control arms fully down is not good for them either so I think I will repeat the test with the front driveline removed. If the rear end and transfer case end up quiet after this test I know it is the Front differential but I really hope not. I have never rebuilt one of the front diffs and do not want to learn that one.

Had one with 4.10 gears, was thinking of switching to 3.42 gears for better MPG. I installed a rear diff with 3.42’s and for this test removed the front driveshaft and drove it about 300 miles. MPG was basically the same and the vehicle felt slow off the line after running the 4.10 ratio fso I reinstalled the 4.10 gears. Had to clear the codes of course but no other issues. For my use I really liked the 4.10 gear ratio and would get one again.

A fried Viscous Coupling does not lock up. The fluid overheats and loses it's ability to resist shear, and thus do anything. The VC acts to limit speed differences between the front and the rear. The VC is the money part in the AWD unit. But it is absolutely your BW AWD unit to do with what you want.

This is why they they make horrible sounds when ran on the lift. Those sounds arent happy sounds either.

Front and rear diffs are ridiculously easy to rebuild, its the setup that is an art and if not done properly the diff will live a very short life. Ive seen them get destroyed just going across town after an improper setup.

I distinctly remember a guy rolling up in his 5.0 in the late 90s and he couldnt slam on the gas no more. One of his buddies did him a "solid" and regeared the diff for him and before he made it across town there was less than 50% of the teeth left. There was actually "neutral" spots in the diff because of it. The grinding noise was one of those you never forget.

 

[Saucy_Walnuts]

A update to my post. After getting it in the air and checking where the noise was it's coming from the rear axle after all. Around the pinion/ ring gear area. I've purchased a roller 4x4 01 Tahoe frame with both axles in 3:73 to swap over. Got lucky and all suspension components seem to be nearly new. I started a new thread if anyone wants to follow along with the swap this weekend and see the results. I'm figuring it will be a all Saturday affair.