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Rear Diff care

Jag_

Rear Diff care

Postby Jag_ » Sat Jun 30, 2012 9:00 pm

I've been reading a lot lately about problems with the rear diff bearings / pinion seals wearing or leaking, etc. Seems it is quite a common issue after about 80000 miles and awkward to repair, due to having to remove the heavy rear subframe.

My diff is currently ok and I changed the fluid recently. But, just wondering if anyone uses a heavier / thicker oil than the original SAE90 GL5, say something like 140 ? Would it help prevent such diff problems? Would if adversly affect the fuel ecconomy in a noticeable way?

Any thoughts appreciated,

John

old del boy
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Re: Rear Diff care

Postby old del boy » Sun Jul 01, 2012 1:05 am

Personally i wouldn't use anything other than what's recommended , mainly because if it were any better i'm sure jaguar would have fitted it in the first place , secondly i just don't do the mileage to warrant the fuss so i stick to this stuff and change it a bit more often than the schedule suggests ,

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Derek..
'93 4.0L Daimler, solent blue,
'93 4.0L Daimler, Westminster,
'85 2600 Rover sd1 vdp oporto.

Jag_

Re: Rear Diff care

Postby Jag_ » Sun Jul 01, 2012 3:23 am

Hi Derek,

I changed the fluid when I got the car, with the modern equivalent of the stuff Jag originally spec. But, having bought the car with 100k miles on it, I don't know how often it has been changed previously. My diff is fine and quiet at the moment, but repairing / changing it, is a job I would really rather avoid. So I would be happy to change the fluid again for some top-notch 75-140w stuff, if folk think it will help prevent future failure, for a bit longer? I am doing a fair bit of mileage in this car, (Just enjoy driving it so much!), so it is in regular use and I would always rather prevent a problem than fix one if possible.

I did notice some light oil leaks around the output shafts, when I did change the fluid. But, these were not fresh and haven't re-appeared since I wiped it all down and put the new fluid in, so obviously not leaking much, if at all now. I read on a USA Jag forum that some peopel had put this Lucas brand 75-140w stuff in as prevention and just wondered if anyone here has done the same? I think I might give it a go anyway.

John

Jaguarrecycling
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Re: Rear Diff care

Postby Jaguarrecycling » Wed Jul 11, 2012 5:43 pm

XJ40 Diffs seem to get a lot of bad press, I don't think that they are as bad as people make out personaly. I rarely get asked for them, and have never changed one.

Its worth changing the oil every 5 years or 50,000 miles which ever is soonest, using the reconmended oil, other than that, if it aint broke dont fix it.
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Jag_

Re: Rear Diff care

Postby Jag_ » Fri Jul 13, 2012 8:58 am

Jaguarrecycling wrote:XJ40 Diffs seem to get a lot of bad press, I don't think that they are as bad as people make out personaly. I rarely get asked for them, and have never changed one..


It's refreshing to hear somone say they are not too bad, gives me a bit of hope! I have read so much about failing output shaft seals, or diffs whinning, that I have become almost convinced my diff will fail fairly soon!

I read in the latest 'Practical Classics' that the Editor has just had to swap his diff on his XJ40 and looking on the internet it seems to be a really common issue.

I just know it is a job I would struggle to do myself, so I want to prevent problems if at all possible.

Do you think the 80/140w oil would lessen the likelyhood of seal or diff failure?

John

naki_k
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Re: Rear Diff care

Postby naki_k » Fri Jul 13, 2012 9:37 am

I think the only reason diffs fail is if the oil leaks out/ if it's not changed enough. I doubt they would fail through any design fault weakness as such?
Am not sure how much thicker the oil needs to be for it to not leak through a worn seal either?

The diff on my 3.2s leaks from the pinion seal. You see all the sludgy stuff, in the middle of the A frame. When I first changed the diff oil it was only half full, and quite thick and sludgy at that. Not good. But it still was quiet/ no whining! No idea how long it was like that, mileage was 97k at the time.

I have tried Lucas oil stop leak in the jag diff, I think it has slowed it down.
Used the same stuff in the rear diff in the range rover and it did stop the pinion seal leak on that!
88 3.6 XJ6 PDH/CEM
90 Range Rover Vogue SE 3.9 V8 LPG
91 4.0 XJ6 Manual
92 4.0 XJR Manual
92 4.0 XJR
93 3.2s - 4.0 Manual conv
93 4.0 Sovereign
93 6.0 XJ81 DD6 x2
93 6.0 XJ81 XJ12
94 4.0 XJR
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Breaking 40/ 300

Equinoxstudios
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Re: Rear Diff care

Postby Equinoxstudios » Fri Jul 13, 2012 9:40 am

Just like our Del, I used...

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bought from Opie oils. My only caveat is that you shouldn't fill it with the car jacked up at the back as you will overfill it. Always fill with the car lowered to the ground.

My car has developed an input shaft leak at 108000mls and I am deeply disturbed :cry: . It's the only niggle in an otherwise well behaved vehicle. I need some reassuring therapy from the people on here...
1994 XJ40 Sovereign 4.0 Brooklands Green
Surrey Hants Border xj40.com Regional Rep
email: surreyhantsborder.xj40com@gmail.com
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Only dull people are brilliant at breakfast

Jag_

Re: Rear Diff care

Postby Jag_ » Fri Jul 13, 2012 10:11 am

naki_k wrote:The diff on my 3.2s leaks from the pinion seal. You see all the sludgy stuff, in the middle of the A frame. When I first changed the diff oil it was only half full, and quite thick and sludgy at that. Not good. But it still was quiet/ no whining! No idea how long it was like that, mileage was 97k at the time.


That is pretty much the situation I found when I changed my diff oil when I bought the car.
It seems like these diff's are ok up to ariound the 100k miles mark then leaks often appear and seals may need replacement. This is what I really want to avoid, as it sounds like such a difficult job at home.

I added 'Wynns Stop leak' which I presume is similar to the Lucas stuff you used. As I said, it does appear to have halted the leak for the time being, just wondering if a much thicker oil would provide extra protection, longer term?

John

naki_k
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Re: Rear Diff care

Postby naki_k » Fri Jul 13, 2012 11:27 am

Jag_ wrote:I added 'Wynns Stop leak' which I presume is similar to the Lucas stuff you used. As I said, it does appear to have halted the leak for the time being, just wondering if a much thicker oil would provide extra protection, longer term?


not sure about the wynns stuff, but the lucas oil additive is very thick anyhow. so i have gone for standard diff oil, plus additive.
if you leak has stopped now anyhow, i would leave it at that and monitor it.

did you use the paint pot lid, entry point through the rear bulkhead to change the diff oil?
i know some members use a pump from below?
88 3.6 XJ6 PDH/CEM
90 Range Rover Vogue SE 3.9 V8 LPG
91 4.0 XJ6 Manual
92 4.0 XJR Manual
92 4.0 XJR
93 3.2s - 4.0 Manual conv
93 4.0 Sovereign
93 6.0 XJ81 DD6 x2
93 6.0 XJ81 XJ12
94 4.0 XJR
94 4.0 Daimler
96 4.0 X306 XJR
96 4.0 X300 D6
97 4.0 X300 Sport Manual
2000 LR Discovery ES TD5 A
Breaking 40/ 300

Jag_

Re: Rear Diff care

Postby Jag_ » Fri Jul 13, 2012 12:26 pm

naki_k wrote:
Jag_ wrote:I added 'Wynns Stop leak' which I presume is similar to the Lucas stuff you used. As I said, it does appear to have halted the leak for the time being, just wondering if a much thicker oil would provide extra protection, longer term?


not sure about the wynns stuff, but the lucas oil additive is very thick anyhow. so i have gone for standard diff oil, plus additive.
if you leak has stopped now anyhow, i would leave it at that and monitor it.

did you use the paint pot lid, entry point through the rear bulkhead to change the diff oil?
i know some members use a pump from below?


I did not know about the entry point through the rear bulkhead, at the time, so I did it with the car jacked up, but only just enough to get under. I drained the old oil in to a measuring jug, realised that it had been quite low and put in a fraction over 2L. I figured that I would have not got it all out, there would probably be around 60-80ml left in, so adding a shade over 2L should bring it to approx the right level.

The Wynns stop leak is fairly thick, but that was only 120ml of the fill. The fresh oil seemed thin compared to the old oil that came out. I guess 80/140w isn't going to hurt, although it may affect fuel ecconomy slightly?

John


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