Greetings Gentlemen!

I got a pinion seal change at a LR dealer and not long after I started getting a humming noise from the rear diff when I press the gas pedal, so under load. It is not loud, but it is noticeable, and it certainly wasn't there before.

The car is currently back at the dealer, and after confirming there is indeed a noise coming out of the rear diff region, they claim it is an issue with the diff itself, and are suggesting a replacement. The price is obviously absurd.

Now, I have asked a reputable independent shop, and they suggest it is highly likely that something is done too tight during the pinion seal change, and that is the most probably cause. I tend to think the same, as the car was perfectly fine before the pinion seal leak was registered, and the dealer changed it.

Another suggestion is that the double-bearing behind the seal might be the problem, and that is an inexpensive job.

What would you advise is done in this situation? Shall I ask the dealer to do another pinion seal change, with the bearing as well, and see if the noise will go away? New diff would be my absolute last resort, as you can imagine. The car has only done around 80k miles and I really don't believe the diff needs changing.

Many thanks!

The pinion preload is very sensitive, so it very well could be over tightened.

As I understand it, there is a single use crush washer which compresses down in shape when the pinion nut is tightened to the correct torque so the preload on the gearing is correct ... if you disassemble and reassemble using the same crush washer, and re-tighten down to the same torque, the crush washer might crush again it may preload the gearing wrongly.

So when you're doing pinion seal work, you have to mark up and record how many turns it took to undo the nut, and then re-tighten using the exactly same number of turns so that it goes back to exactly the same place and preloads are kept the same and the washer is not crushed further.

I think I would be going back to the dealer to ask them to fix it. they have created and issue with the car from their work, which they have acknowledged by agreeing they can hear the sound. V8 or else ...

Plus 1 on Fisha's theory. My friend had exactly the same problem on a Jag Sportbrake after a pinion seal replacement. I think the crush tube or washer is designed to only be used once. The garage/Main dealer eventually admitted responsibility and fitted a new diff. Fingers crossed that you have a good outcome.