Oil leak from Diff

[Wedding_Car]

ok theres a fair amount of oil all around the underside of my moggy 1000 at the rear end and it appears to be coming from the diff.

Is there a seal that commonly fails? or is it more terminal? Doesn't seem to be making any nasty noises just loosing lots of oil!

cheers
john

[ColinP]

Can you spot the source any more accurately?

I have two locations for oil "drops" - no more than a spot or two:

1) rear axle drain plug (the threads of both the plug and the hole need to be clean - well cleaner than I did last time - to reduce the leakage).

2) The oil breather (top of axle to LH side of car from the bump). This seems to have the occasional drop or two

Colin

[simmitc]

There is an oil seal on the diff. Doesn't normally give much trouble, but obviously could be worn. It can be replaced with the diff in situ: Remove prop shaft, undo centre nut to allow glange to be withdrawn from diff. Locate & change seal and refit. Sorry it's a bit vague, it must be ten years since I last had to do one; but the workshop manuals do cover this OK. Good luck.

[Willie]

As SIMMITE says there is an easily changeable oil seal on the
pinion flange. You can usually tell because the oil has been
flung across the chassis in line with the prop shaft U/J. There is
no locking plate on the pinion nut so you just need a hefty spanner
(and a way of stopping the flange from turning)! This oil seal is a
special one, not the same as the rear hub seal, so you need to order
the specific item.

[bmcecosse]

Check the diff is not overfilled to start with ! Changing the seal involves releasing the drive flange nut - but the tightness of this nut sets the pre-load clearance in the diff - and so it should not be fiddled with unless you know what you are doing. If the leak is slight - live with it - at least it stops the car rusting.

[Willie]

The pinion flange nut should be tightened to 140 ft.lbs. as per
workshop manual.

[bmcecosse]

Not necessarily ! It's more difficult than that - which is why it shouldn't be fiddled with unless absolutely necessary.

[Willie]

BMC.....The pinion pre-load should be set during assembly BY
USING SHIMS until, with the pinion nut at 140 ft lbs, it is within
limits. I say 'should be set' since it is difficult to obtain a diff
unit which has been properly assembled these days. Once the
necessary shims have been fitted you can remove and refit the
pinion nut as often as you wish without altering the preload as long
as it is re-tightened to 140 ft lbs.