C 8.25 Gear Whine
 

I've owned my XJ for over 3 years and put almost 60k miles on it. The rear end has whined since I've owned it, and the person I bought it from informed me at the time of purchase that it's whined since he's owned it. (I forget how long he owned it.)

The rearend only whines under load (accel), but quietens up on decel and when coasting. It's been one of those things that if ain't broke, don't fix it. The whine hasn't changed over the years, it's just as it was when I bought it.

Do I keep the "if it ain't broke don't fix it" mentality, or could someone point me in the right direction? I did a quick search and came up short - which leads me to believe - I have a "problem" since I couldn't find much info on it.

Thanks in advance!

First things first. Have you checked the fluid level? If it has never been changed it is probably thin and used up. Moisture has ways of getting into the axle housings, especially if the vent tubes have not been rerouted higher up and it sees a lot of mud. Check the fluid level and change it if it is dark and watery.

+1

Check and/or change the gear oil. Jeeps like 75W/140 synthetic in the rear axle with a friction-modifier additive.

I've seen MOPAR diffs whine for years-and-years (my '68 Dart whined for over 100,000 miles).

I had the same exact whine in my 8.25 and it turned out to be the outer pinion bearing even though it was not leaking gear oil. Disconnect the rear drive shaft and try moving around the yolk on the rear, if you have any play it would most likely be that...Tj

Shame on me, my short answer is "no" on checking the fluid level. I'm going to do that tomorrow once it warms up a few degrees. I guess my only reason for not checking it is the fear of what I may find! :D

I may as well change it while I am under there though. Does the friction additive need to be a Mopar fluid? I used to own a GM with the shiddy 7.5" dif, and the GM additive was a necessity when changing the fluid.

I'll check the yoke too (thanks for the input).

Sadly, the Jeep sees more pavement than it does offroad. But, re-routing the vent tubes seems like a nice helpful (preventative) mod. I may as well do that while I'm down below as well!