Drivetrain squeal only after driving 10 or 20 minutes

Loud squeal from (I think) the front end, could be midway back, but well forward of the rear axle. Occurs in 2wd or 4wd. Under braking, accelerating and while coasting. Turning left/right has no noticeable effect. Turning the engine off and coasting out of gear it's still there too. Here's where the fun starts - I put the whole truck off the ground and into 4wd and couldn't hear it. There is no slop in either front tire when rocking from 12 to 6 o'clock or from 3 to 9. It's a squealing noise similar to a squeaky belt or the wear indicator on low brake pads. Kind of sounds like a bearing with a failed seal that has run dry on grease or had some internal corrosion going on. Currently only hearing it after freeway driving for at least 5 or 10 minutes. Sounds a little louder on the driver side, but also hearing it from the passenger side as well. If everything cools down it's dead silent. The longer I drive at faster speeds (over 40-50ish) the louder it gets.

I am lifted on OME 2883 coils on stock control arms up front. I had a shop replace my CV axles recently, but it's not the click/clack noise I'd expect to hear from a CV if I'd gotten a bad one. I'm also on a recently replaced steering rack, sway bar bushings, and sway bar end links. 190,000mi

Headed to pick up a grease gun and hit all the zirc fittings on the driveshafts. Also thinking carrier bearing on the driveshaft as I've heard those make a similar sound, but I have no excessive slop there and no vibration associated with the sound.

We were planning on heading to Baja on the 26th and I'd like to figure out what's going on here before leaving. We're in Poway staying for Xmas at my girlfriend's parents house, if anyone in the area feels like troubleshooting, wrenching and escaping their holiday scene at home, I'd welcome any and all forms of help. Payment offered in the form of beer, high fives and karma points for anything that helps us out.

Backstory / full noise history:
It started about 800mi ago I heard a faint squeak after highway driving long enough to get things warmed up. I'd only hear it from about 20 to 35mph and it would go away at speeds above or below that range. I just drove from SF down to San Diego last night and the noise was very audible, increasing in volume through the drive and occurring at a wider and wider range of speeds to the point that I'd hear it from 0 to 75+mph. Pulling into San Diego last night it was a loud non-stop squeak/squeal. Hoped in the car this morning after it cooled down overnight and... dead silent. Did some freeway driving and it came back in 5 minutes.

Link to video of sound today, couldn't get my .mp4 video to upload because it's not an accepted file type. (Why?!?)
https://photos.app.goo.gl/nE2YFyWYF7HwK6kWA

 

Found It!?! So after more investigation and driving I was able to reproduce the squealing noise in 4wd with the front end on jackstands and the rear axle jacked up on the diff. It's coming from the drivers side where the CV axle meets the front diff. There was a trail of diff fluid leaking from that area down the diff. It appeared slightly wet and the skid had a corresponding wettish spot. Comparing the drivers side to the passenger side it seemed like maybe the CV axle wasn't seated correctly or completely into the diff. Squirting WD-40 aimed at the gap in between the silver flange on the CV axle and the diff made the noise go away for a few seconds so I'm fairly certain this is where the noise is coming from. See pictures of both sides below. Driver side first, Passenger side second. Anyone have any ideas what's going on here? I had the CV's replaced before I started hearing the noise but it didn't start immediately, took a couple hundred miles to come on. We're supposed to leave for Baja at 6AM on the 26th and I need to figure this out before heading out.

 

Do you remember if it leaked before the repair, the axle may not be seated properly. Does it only make the noise in 4wd?

 

Tried to get a couple photos of my driver side for comparison. It seems on mine the metal ring is flush with the diff housing.

Trying to remember but I had a squeak on my old 4TR when a rock got stuck behind the dust shield on one of the brakes. Maybe worth a look there?

 

Looks like the seal are in differently to me.
One is bell out and the leaky one is bell in,

 

No leak there before new CVs went in as far as I know, definitely wasn't squealing right there either. The CV axle has significantly more movement on the driver's side as well (compared to the passenger side). In/out of the diff as well as up/down and forward/back. Going to pull the CV axle today and check the seals inside the diff as well as inspect that end of the CV axle for any strange wear marks. That metal dust shield that is sitting proud on the driver's side - does anyone know which way that is supposed to sit on the CV? It's not flat, but is stamped to have a little bit of an offset. Is it supposed to sit with the offset facing so it is cupped/stepped in toward the diff or out toward the CV? Will take photos and post later.

It seems the needle bearing inside the diff is a common failure item on lifted 2nd gens and sometimes on lifted first gens. What had me thinking that may not my culprit here is I felt no noticeable vibration and changing between 2wd and 4wd had little to no effect.

 

Well, I think I figured out what the problem was.... pulled the CV axle out and there were two dust covers in there!! Gonna have some words with my mechanic when I get back home from our trip... Reassembled everything and took her for some freeway driving and we're squeal squawk and squeak free.



Side note these are really hard to get out when they don't come with the recessed indentations on the sides of the inner joint to tap on with a pry bar... I ended up using a hi-lift, a chain and some spectra to pull the inner CV out of the diff! Gonna keep an eye on the diff there and make sure it doesn't keep leaking but thinking it should work better with the seals all seated correctly.

 

Excellent, glad you found the issue and not an expensive one to fix!