Hello,

I have an howling sound coming from what I thinks is the differential. The sound is present between 45 and 70mph, only if the accelerator is pressed, and it doesn't change if i'm in 4-5-6th gear or swerving. The "JTB00175" TSB and the problems on the S-Types that have the same diff points me in that direction.

For the moment I did on oil change on the diff, the old one looked very bad the shop said. I have also tried an additive, it did nothing. I have to face the truth, the diff is in bad shape.
From the forums I managed to get 4 solutions to solve this problem.

1) Find a shop that can rebuild the diff : change the bearings, adjust differents things inside etc. The problem is that my XK is my daily driver and I don't have any other vehicle, I can't put it on jackstands for 2-3 weeks

2) Put a used 4.0 S-type 3.31 diff ratio (PN : XR81871) + the 2 half-shafts (PN : XR82893/XR82894).

3) Buy the same diff but a new/reconditionned one from a reliable shop (PN : C2C34880)

4) Do the TSB mentionned previously but the price is too high, just in parts it would be 4k€+

I'm actually hesitating between 2) and 3), the price will be a bit higher doing the 3) but it's manageable.
It's a car that I plan to keep and put miles on it. The 3) seems to be the best one but will the diff hold the distance ? Or will it be trash in 120kkm as the one I have actually ?
The diff from the 4.0 S-type will be a used one as the new one can't be find or at crazy prices, is this diff known to be "bulletproof" or may it go bad too ?

Thanks in advance for your answers, if you any questions or suggestions do not hesitate !

 

Have you looked under the car , any oil leaks from diff ?

 

Assuming you've diagnosed the problem correctly, one suggestion would be to replace it wit a Quaife LSD. They run about $1400 US I think or about $1200 euros. A few guys here have installed one and can confirm for you. Also, can you post the TSB please? I have a copy but none of the pics are in the TSB. Should be TSB JTB00175v3. dated 12/2010.

 

LSD I remember coming round from an op in the hospital years ago , A delightful woman on the nite shift tended to me the body of miss world , 3 nites later and off the drugs she was back on shift weighted over 20 stone lol

 

I have looked, the diff is bone dry.
I also checked the level of oil when I added the additive, it was good when I opened the fill plug. And I filled it until the oil runs from the fill hole when I was done

EDIT : I read about the Quaife, seems to be a straight swap from what I saw, but I don't have the skills nor the tools to set it right, and I don't have a trusty shop to do that for me either ..
You're right, it's TSB JTB00175v3, I think you have the same copy as me because I don't have any pictures on it too. The pictures should be on the manual service as it's the same step

 

Jascum has a gen 2 diff available on marketplace for a very very reasonable price I'd jump on that straight away

 

The usual failure that causes whining in these diffs is a chewed out pinion bearing, which then leads to chewed out gears.

In which case a Quaife is not going to solve this problem...

Fortunately these 3.31 diffs were used in other Jags, like the S-Type with the 3.0L V6, and the X350 XJ with the 3.0L V6.

So finding a 2nd hand one that is a straight swap will be the most cost-effective fix.

 

To be absolutely sure of your diagnosis, I'd get the car up on a lift and listen to the rear with a stethoscope. Then you would know with certainty. Good luck and let us know how you make out.

 

This is v6 and with pictures.

 

@Cambo is bang on.
You mentioned 'additive'... What additive?!? That may have cooked you right there. And it sounds as if you have too much fluid in there as well. That fill port is not a levelling guide.
I still run with the original differential but I had bearings and seals replaced at 100,000. there was no drama and it was completed in 2 days.
(Sadly, I did not locate a cost effective quaife LSD add-on in time)
Anyhow, setting the shims and gears in a differential is finicky work. I left it to the pros.

Another alternative, though I'm not sure of its viability in FR, Take a look at @Ranchero50 's solution. It's pretty cool.

Cheers.

 

Has anybody here from new Zealand found a qualified Differential engineer. I bought my 2006 S type in 2015 and it had a small noise which has gotten noisier as the years rolled past. I am 70 years old and wanted my Jag to live as long as I do but the Diff is really starting to **** me off. Anybody? Recommendations? I'm not a mechanic so I can't do this stuff myself. I realise it may be expensive but I wish to keep this car til I die.

 

ReDDog - I think you are in the wrong Forum. This Forum is for Jag X150's otherwise known as XKs and XKRs built from 2006 to 2014. From your posting it sounds like you have a 2006 S Type. Try that Forum and you will have better luck. Maybe a moderator will move your posting.

 

Ralph is correct you are in the wrong forum section however we do in fact share the same series 2 differential along with 03-06 Lincoln ls / Ford thunderbird