I've been reading posts about worn pinion bearings a few at a time for a couple of months and I'm fairly sure thats what I have going on but, I want to run it by you guys before I bite the bullet and drop the cash. My xj has an 8.25 and it whines when the gas is slightly pressed. If I let off it stops and if I accelerate it stops. It's just when the gas is pushed at roughly a "cruising preasure". I can get a little movement at the front of the rear d/s. I'm replacing that u joint on monday. I can't get any play at the pinion end And there is no leaking at the pinion end either. I called a local shop and they said $400-450 to replace the bearings in my rear end. I'm ok with paying that because I'll know that's one less thing to have to worry about in the future (vs buying a J/Y rear end and throwing it in) but, I want to make sure that's what it is before I take it to them. I replaced the fluid about 6 months ago and the teeth on the gears looked good. It sound like it come from the rear end but, I've also wondered if it could be the output bearing on the tcase and the sound just seems to be coming from the rear. Sorry about the long rambling post. All I really wanted to know is if anyone has advice based off of the sound.

 

anybody?

 

Eventually a bad bearing will run hot, then very hot, then smoken hot. Maybe just change the U-Joints and keep a watch on it.

 

I didn't change the u joint yesterday Like I'd planned. I had other things come up. I'll get to it soon though. I'm still wondering if that sounds like a worn pinion/carrier bearing though. It only whines at slight throttle. If I let off it stops and if I give it enough gas to accelerate it stops.

 

This EXACTLY what mine does. It starts at about 42-43 mph and lasts until about 50 and stops. It only does it when I am gradually getting up to speed and only when accelerating. Did you ever find out what it was exactly?