Please help. I have a 2001 xj and recently the rear end has been making this whoo whoo whoo gringing noise. Started about a week ago. I put my jeep up on jack stands and ran it. Noise is coming from the rear christler 8.25 diff. When i did my physical inspection on the driveshaft near the yolk it did not move horizontal or vertical. I then drained and opened the diff for a visual inspection. When i inspected it everything was normal. No broken teeth, no abnormal wear, nothing.

The noise only happens when i reach 10-15mph and faster and when the jeep goes faster the noise speeds up with it. When i let off the gas and coast its not audibly noticable, but when i have my foot on the accelerator and am accelerating is when you can audibly hear it the best. Even while coasting with accelerator on the noise is audible.

Its a stock 2001 xj. U-joints look good, that was my initial thought. I will try to post a video of the noise i made. Again its a gringing whooo whoo whooo sound coming from the rear end.

im new to this forum so if i posted in the wrong place my apologies.

 

https://www.youtube.com/watch?v=iGNSBRy95jQ&feature=share

again you have to listen but its a grinding whooo whooo whooo sound. Best i can describe it

 

This definitely sounds like my issue and I'm checking the pinion bearing and pinion seal. That's where I would tell you to check those two.