Whining noise when let off gas (low speed)

Hey I'm brand new to posting on this forum, done lots of searching through it for an answer but can't find a problem quite like mine with advice. Anyways I have a 2001 4WD 5M TRD (190,000 km : 118,000 miles), and after about 3 hours of highway driving when I got home I noticed a loud whine coming from under the truck when approaching a stop when I let off the gas and am coasting. When I re-apply gas or hit the brakes it goes away, and this only happens (from what I can tell) in 1st gear, tried doing the same thing in 2nd gear and I don't hear the whining noise. Any thoughts on diagnosis or what I can do to figure it out? I'll bring it to dealer this week, but I have a feeling they're going to charge a fortune to diagnose or someone on here might know the answer an potential fix. Hoping this isn't a fatal blow as its been a wonderfully reliable truck. Thanks for any input!

 

From what you describe (noise when letting off gas) I'm thinking pinion bearing, can you get some audio possibly ?? It'd help tons...

 

Ya sure I can grab a video of it tonight, just another piece of info is that it does make noise when stopping in 2nd gear also now that I listen closer (although not as audible), if I roll to a stop in neutral or put the clutch in when I'm coasting to a stop the noise disappears completely.

 

Yeah, do that It probably is the pinion bearing but some decent audio will def. nail it down if it is....

 

Here is the audio/video. In 1st gear cycling gas on and off...the noise is once I come off the gas. Thanks

https://www.youtube.com/watch?v=TM9Wa0BQS8g&index=1&list=UUhU-FJ4pogl_YEH1w8rxjyw

 

Hahaha, you got some birds in the cab with you ?? Not the pinion (lucky for you) Smart money says you've got a U joint getting ready to shit itself....

 

Haha make the truck blend in with the neighbourhood birds better.

Just climbed under to inspect the u-joints, no major play in any of them but a little bit in the front and rear, all very dry and basically no grease. I appreciate the input, just looking for an opinion online so if I get told I need a new tranny and diff I don't get totally hosed.

 

Yeah, that "chirp chirp" i was hearing is almost text book Ujoints with the needle bearings destroying themselves, most the time when a rear joint is going out it sounds like a piece of wire wrapped around the driveshaft & also this noise starts on take off, not deceleration, but I still think thats your problem tho'...make sure to let us know....

 

So your assessment was pretty much correct, rear U-joint was shot. Fixed and sounds good now. As I was driving it over to the shop, I was beginning to get that noise on on acceleration and also a very very small vibration. $300 to fix, probably could have shopped around or maybe tackled it myself for cheaper but I need my truck back ASAP so just got it done. Thanks for the help with the diagnosis!

 

No worries dude, glad to help & glad you got'er handled....