The whining from the rear diff on my 2001 XJ8 3.2 is less than before I changed the oil, but it still makes too much noise.
From reading old threads I understand I should change the output bearings and seals, does this sound reasonable? Anything else?

Thanks very much for any advice...

 

Differentials with noise can be a number of things. Usually if you have a whining noise its from a deteriorating part. It could be a carrier bearing in the rear hub or a shim gone bad and a complete breakdown rebuild.
Have you checked your universals on your output shafts or driveshaft? They would be the most likely suspect I would consider. An initial simple quick, but not for sure, check...would be to put the car in gear as your door is open to listen for any clunking. Then you need to get under her and work the joints.
Be sure to check the pinion also, check the seal for seepage.

 

Just been there, had a bit of a noisy diff, replaced all 4 UJs, better for a while, but still had play at the rear wheels, (jack up and try pushing/pulling the wheel in and out) that was not the wheel bearings.


Output bearings then, ordered the bearings JLM20337 £225.35 each, collar C2A1421 £18.24 each and circlip C2A1422 £13.61 each all plus the dreaded VAT at 20% so about £620 all in.


Fitted them, and within less than 100 miles the diff itself went BANG!


Second hand diff from ebay £200 inc delivery!


With hindsight I know which way I would go, £200 delivered with a 90 day warranty,
plus 2 litres of oil and 2 new oil seals for the bearings JLM20451 £12.66 each + VAT,
I changed the output shafts with the new bearings into the used diff, but for £30 or so I would change the seals anyway before fitting a used diff, its only a half hour job while the diff is on the bench.

 

Mine was really noisy and I just ignored it. Bad on my part when something exploded internally and blew a hole in the back of the housing. $2500 later it's nice and quiet. Lesson learned.