SOLVED -diagnosing driveline "whine"

Looking for help on what this noise might be and what other tests can I do to narrow down what might be the cause. FYI it is NOT that loud inside the cab but I want to fix anything before it gets worse (assuming something is actually going out). Oh it's not tires either because I tried my dads' wheels and noise was still there.

2003 Double cab short bed auto trans 216,000 miles / no shavings on rear diff drain plug & fluid looked fine but I changed it anyway / transfer case & transmission fluids good/levels fine, ujoints greased at every oil change, etc. I think the noise started within last month.

-Sounds like a high pitch whine; noticeable between 20-40mph then goes away at higher speeds
-No vibrations at all
-No clunks when shifting from neutral to drive, etc.
-It makes the same noise with the engine off (coasting in neutral so pretty sure it's not the engine and something in the driveline).
-Makes same noise in 4wd and going around corners

Okay so listen at the 4-8 second mark in this video to hear the whine noise
https://drive.google.com/file/d/1rsYDwtcG8bY15gb8Z2gak04kk9eqEGNF/view?usp=sharing

I did this test today with someone pressing gas pedal in drive to get speed up to 30mph
https://drive.google.com/file/d/1iAxtGkk4-GUGaa5v6pBBmuFzNKTDf2Xe/view?usp=sharing

Here is same test on my dad's 2003 extra cab (manual trans) and it does NOT have that high pitch squeal
https://drive.google.com/file/d/1DQskD92CmYwYmErUmUdRc75x3x7HrIYj/view?usp=sharing

Could it be my double cardan joint? Mine has a noticeable sound that my dads truck does NOT
Mine
https://drive.google.com/file/d/1EbSlR9m5x1UCWd8R7PCvZ-vToEGQCYij/view?usp=sharing

My dad's double cardan joint with no noise
https://drive.google.com/file/d/1fy9A4TO-k2IYkM8ts4k7k8utNZAHaI0A/view?usp=sharing

I'm thinking I could remove entire rear drive shaft from transfer case to pinion (make markings first of course) and then drive in 4wd. If so goes away I know its in the drafts haft or carrier bearing. Thoughts?

Thanks in advance!!

 

Noise diagnoses over videos is always difficult but you have done one of the most complete and good quality I’ve seen. It sounds like bearing noise and if I had to speculate without being there I’d say pinion bearing in the rear differential. I would run it on stands like you have and use a mechanics stethoscope to narrow it down.
good luck

 

Thanks for compliment and the reply Slaps! Yeah I have a stethoscope so will try that first. Not sure why I'm so tentative about removing the drive shaft. If I make etching marks and properly retorque the nuts it shouldn't be an issue.

Assuming I drive it around block with JUST front drive shaft (rear removed) and it still makes the noise, I believe it's likely the pinion bearing because the pinion shaft would still be spinning. Will definitely post a reply once I figure it out to help any others.

 

Slaps was correct, turned out the front pinion bearing was bad. Owner of a local rear end shop rode in my truck and after about 100' said yep, pinion bearing. Thought I would post in case anyone else hears low speed growling that turns to whine around 30-40mph.

Here is bad front bearing, this was the worse roller. Rest looked fine.



Other bearings came out in one piece

 

please tell me they didnt put in chineese bearings.

 

Buy you got your mileage out of that pinion bearing. Good deal and thanks for posting.

 

They didn’t, some USA brand I can’t recall. He said Timken aren’t available for that specific bearing. Totally reputable shop and gave me 3 year warranty.

 

good, had me worried.

 

wow! glad you figured it out. that bearing is pretty gashed up!