Whining XJ40 Diff?

[smiller]

Got a 1988 Daimler XJ40, and there is a "whining" noise coming from the rear which gets more obtrusive the faster I go. I'm suspecting it's the diff, but I'm no expert.

Any thoughts?

[Jaguar steve]

Could be. If the whine changes with power on/off and generally gets louder with a speed increase it's likley to be the culprit.

Change the oil ASAP. Chances are damage is already done, but it's worth a try.

You might want to consider some Penrite EP 85 - 140 gear oil if you can get it. I know it's not the correct spec. for the XJ40 but the higher viscositity does quite a good job in masking the noise.

If it's an LSD you'll need to use an oil with the correct addatives. If you don't know check by jacking the rear up and turning a wheel. If the opposite wheel rotates in the same direction its an LSD, if it goes in the opposite diredtion its not

[Swoxy]

I can't tell you anything technical but my old man's '90 XJ6 4.0 did this and it was diagnosed as the diff.

[NormanD]

Jaguar steve said:

If the opposite wheel rotates in the same direction its an LSD, if it goes in the opposite direction its not

That is a verry good tip, THANKS Steve

[smiller]

Jaguar steve said:

Could be. If the whine changes with power on/off and generally gets louder with a speed increase it's likley to be the culprit.

The sound remains the same (must be a Led Zeppelin type diff ) whether power is applied or not, but gets louder the faster I go. Is an oil replacement still a fix, or am I looking at mechanical replacement?

Cheers!

[NormanD]

smiller said:

Jaguar steve said:

Could be. If the whine changes with power on/off and generally gets louder with a speed increase it's likley to be the culprit.

The sound remains the same (must be a Led Zeppelin type diff ) whether power is applied or not, but gets louder the faster I go. Is an oil replacement still a fix, or am I looking at mechanical replacement?

Sounds as it it is to late for an oil replacement.


Now if you were going to sell the car, the old sawdust in the diff will do the trick.

[Jaguar steve]

Changing the oil was never a fix...more of a bodge. It's quite likley your diff. will keep going on for years and the whine may not get much worse.

Depends on how much it annoys you if you decide to get it repaired or not. Providing it's got plenty of clean oil in it it's very unlikley to suddenly fail.

IMO it's worth trying Penrite oil, or any other EP 85-140 - it worked surprisingly well in my Series 3 which had the same problem.

Eurojag or any other Jaguar breaker should be able to supply you with a good secondhand diff - but it's a long dirty job changing one over.

You could just turn the stereo up. In which case a selection of Zeppelin CDs would be an excellent choice

[smiller]

Jaguar steve said:

You could just turn the stereo up. In which case a selection of Zeppelin CDs would be an excellent choice