No special oil is needed in the diff - any good modern 90W or equivalent gear oil should work fine. The Redline Oil gear oils are excellent. I've also successfully used several of the Lucas gear oils, including the conventional 85W-90 and 85W-140, and the synthetic 75W-90 and 75W-140. Lucas offers a Heavy Duty Oil Stabilizer that will often quiet noisy gears at least a little when substituted for part of the regular gear oil (I start with about 1/8 to 1/4 of the fill to see if that does the trick).

Cheers,

Don

That's interesting Don and Stojanovic, ...good news for KC so he doesn't have to drain the diff. My inde' is somewhat anal (maybe its the Irishmen he is...lol), but he was adamant regarding the fluid I used. So I guess he's infused that in me? Good to know for the future though....thanks.

So I went to the shop, had the owner drive the car to diagnose. He couldn't get it to moan, I took over, drove the car very hard, I mean 0-70 mph sprints w/ hard cornering & turns, zero noise.

This car is a true diva/vixen I tell you.

Noise resurfaced today so I chose to experiment with it. The howl/moan only presents itself if I give it gas in the turn. I hit several curves & turns @ speed using no gas, it rendered no noise.

So applying torque to the gearing is when the noise surfaces....you may want to try Stojanovic's suggestion of the Molly Slip?
Just out of curiosity, have you tried it with the Traction Control off?

No not yet, I'll give that a shot later tonight. I guess I'll buy some Lucus Oil Stabilizer & give that a whirl as well.

You're on to something sir ! W/ Traction Off zero noise, as soon as I turn it back on it's moaning ?! What could this be ? Safe to say for now the traction will remain off lol.

Hi King Charles,

Sounds like Highhorse's question has prompted some progress! I wonder if a malfunction in the Traction Control system is causing the Brake Control Modulator to moan, or perhaps it is causing a rear brake caliper to drag? The X308 Technical Guide refers us to the X100 Technical Guide for an explanation of how the TC System operates. See pdf pages 55 and 56:

Jaguar XK8 Technical Guide and Introduction 1997

Cheers,

Don

Kudos sir ! My 1st thought was the braking system. Of note I did have my ABS module re-soldered last year as I had the worrisome ASC/Trac message. I will mull over this PDF w/ a nice dry London gin & green tea concoction for inspiration.

Months & wheel bearing jobs later I am here lol.

My rear end howl on the other hand, after having been diagnosed a bad driver side rear wheel bearing in 3 different shops. I went back to the shop that supposedly replaced the bearing as it was under warranty. He thoroughly checked everything & says it's the rear differential, he says he checked & found metal particles in the fluid(which was just replaced 1,500 miles ago & was clean then so it's a new issue). he suspects metal on metal. It only howls on curves when gas is applied, it makes no noise if I coast into curves or turns so it's really odd to me. The thing that irks me is why would not 1 not 2, but 3 shops diagnose the rear driver side bearing as the problem, instead of delving deeper as they have now to find a rear diff. issue ?! I have no problem replacing the rear diff. w/a re-manufactured or low mileage used unit. But factor in all the time, not mention $ spent in diagnosis fees, taking the car to different shops etc. It really annoys me lol. I mean how can I trust that it is indeed the rear differential & that will remedy my howling issue ?!

The life of a X308 owner, never boring my friends.

The one person I know almost for sure to give you a direct answer (good or bad) would be Count Iblis. I would PM him and ask him to look at this thread, he has designed a beefer diff for the x308, though its not cheap. But he should be able to help simplify your solution.

Since the 1st bearing job wasn't fruitful I went to another shop whom diagnosed that the bearing was loose & said a bearing job would correct the issue. Being I had a warranty on the 1st "repair" I went back to the initial shop. He's the one saying it's the differential & being he had issues doing the bearing job IE I had to bring the car back hours after the work, because he called & noticed the bearing's dust guard/shield wasn't installed & laying in the shop ?! So my confidence in him is now very low & I fear he is just throwing out possible scenarios to cover a botched bearing job cost he doesn't want to eat on warranty.


I'm going back to the shop that diagnosed the bearing as loose after the 1st job. I was trying to recoup some costs w/ the warranty but it's time this riddle is solved once & for all. I'm going to make sure that these guys know for a fact that it is indeed the wheel bearing as I'm not paying for that repair twice. All in all it's been diagnosed as the rear wheel bearing by 3 different shops one even after a supposed bearing replacement so go figure lol.

Edit :
The more I think about it, it is indeed the wheel bearing. All this surfaced as I was eliminating noises in the rear. I did shocks,rubbers,tires & rear fluid. But I never solved what sounded like a wobble on the rear driver side wheel when I'm going straight over minor bumps, in my mind's eye it does sound like a loose bearing with play when force is applied. Not enough when I checked on jacks though. Then it progressed to the howl, but the wobble sound is always there from the same wheel. I'm done working w/ the shop that did the 1st bearing job. He has me overthinking it to try & cover his ineptitude.

KC,

It would be worth asking the shops that have diagnosed a bad wheel bearing if they used a Chassis Ear system, which has microphones that can be attached to various points like the wheel hub and differential. You then drive the car while the mechanic rides along and listens to the signals from each microphone separately to pinpoint the source of a noise and reduce or eliminate guesswork. The system is made by the Steelman company, but it's also sold under the Snap On, Matco, Mac and Cornwell tool-truck brands. If a shop used Chassis Ear you can have a higher degree of confidence in their diagnosis.

Cheers,

Don

I can't believe this ?! That bearing is so bad that I can actually rock the wheel to & fro w/ my foot with it parked & all the weight on it. How this so called "shop" missed it 3x & went to diagnosing the rear differential has me perplexed. Going to another shop Monday morning & then it's on to my asteroid hunt !

Might have an attorney send the first shop a letter requesting compensation or law suit, their choice! And, believe it or not, the local Better Business Bureau has some clout.

How'z your blood pressure?

Oh I'm calm & cool w/ a nice bottle of Ketel One Botanical vodka in cucumber mint lol. But yes that's absurd to miss it that many x, but then to start guessing & having me thinking the differential had the issues is just unethical.

Doing both rear bearings,the rear springs re-sat,cleaned & lubed, should be ready Wed. or Thursday. They picked up sound & play in the passenger side as well.

I'm wondering if when you disengaged the Traction Control if it took the load off that side and why the noise went away initially? Its probably best you do both sides, your there and there's not time like the present...I say good choice. I'm just miffed at the previous shops lack of ability or wanting to milk you for more.

Yes this technician & shop is well familiar w/ this vintage Jag,BMW,Benz & Porsche, he actually took me back & let me listen to every wheel as well as the nearly silent differential w/ a chassis audio device whilest on the lift. He explained that driving w/ traction off would decrease load equally on both sides if both bearings were in good shape, being one was failing the extra all went to the one that was in better shape, hence it now being prone to failure. This shop is akin to a hospital operating room, everything in place & alarmingly sterile lol. I've always heard great things about this place but the multiple week waiting list pushed me elsewhere. If all goes as planned, I think I've indeed found my shop.

I had an associate that was pretty good w/ X308s but he's seemed to have disappeared into the sunset w/ no notice.

Alas is life, she's in capable hands' now !

Ive just diagnosed issues and noises on my rear end. A definite wheel bearing noise is rearing its head from the rear left wheel, and then I started to get a light clicking/purring noise on the over run. That sounded like a continuous tone kitten purring.

After much provocation I found the rear left wheel has some play in it- I put my hand on the hub assembly and the other on the U joint/half shaft while a colleague shook the wheel.

From this I could tell- that it was the wheel bearing. On the other side- I did the same and found that the U joint has some play in it.

I will have to tackle those.

As for the light 'kitten purring' noise on overrun, I found the bolts for through the jurid coupling to the companion flange at the front of the differential had backed out!

I torqued these up to the required torque (about 82 Nm each). Thus far I haven't been able to reproduce the kitten-purring noise since the tightening.

Usually noises from the rear end on the overrun are related to the pinion side of things. I had assumed the worst that the pinion had lost preload, but I seemed to be wrong. The diff is a beefed up 15HU with Torsen and has barely 17,000 miles on it, but I have been taking it to the drag strip and since I got the AMG blue top solenoids, the fast shifts probably aren't helping.

Once spring comes I'll probably tackle the wheel bearing and U joints then.