Replacing centre diff oil

[Rodda]

hi all I'm going to replace the oil in my centre diff and wondering if I can get any advice before I go ahead with it like what brand of oil was used and how much oil it takes what tools I need any advice or pics will be appropriated.
The car is a 2009 liberty gt-b

[Flat6Estate]

Good luck undoing it...

[BillyCorgi]

The centre diff is a sealed item.
The fluid inside it is a 100,000 cSt silicone fluid (or there abouts)
It is not a user serviceable item.

I have disassembled a standard 5MT Centre Diff.
Once the viscous coupling diff has failed the fluid inside is very icky.
Icky is the best description I can give it.
Be prepared to get VERY dirty.

I was unable to find a supply source of the silicone fluid in Australia.
Dow Corning have a suitable 100,000cSt silicone fluid in their product range, however it is not stocked in Australia.
Here is an American supplier that has an appropriate 100,000 cSt fluid.
http://www.clearcoproducts.com/pure-sil ... osity.html
It can be readily air freighted as the fluid is not on any hazardous material list.
IIRC the smallest lot was 1 USGallon at about USD $100

You would also need to size and obtain new X-Ring seals

There are some videos on youtube regarding home workshop rebuilding/refluiding generic viscous couplings.
LandRovers and VW Caravelles seem to be candidates for home rebuilding.

Last question? Where are you located?

[Rodda]

I'm in Melbourne

[BillyCorgi]

If you were is Sydney I would let you look at the disassembled 5MT centre diff and the internal components and plates, etc.
Such is life.

[Flat6Estate]

What problems were there with the 5MT centre diffs?
My manual RS Impreza (2.5L) had 250000km on it when I sold it, and had no problems with any of the diffs at all.

Or was it only on the higher powered models??? WRX, H6 and GT Lib???

There seems to be no known cause of any failures yet. Maintenance is done by gearbox and diff oil changes every 50,000kms as specified by factory, so what is the cause of the failures?

[RX25SE]

What problems were there with the 5MT centre diffs?

My wife's MY02 RX jerks and carries on on tight turns once the g/box heats up, has done for a while.

I have a spare VCD that I have stripped and cleaned (I suspect it was replaced due to the same issue) as I intend to fit it without seals and just run it as an open diff.

But you are right, we seem to hear much more about the 6MT's diff issues.

[BillyCorgi]

There is not really a problem with the 5MT centre Viscous Differentials, the 5MT model was simply used as an example.
However all viscous diffs will fail if they are pushed beyond a point.
I replaced the centre diff in No.2 Son's MY09 2.5i manual wagon. It failed basically because of something stupid I did. Not saying what due to my embarrassment, but put it down to "school fees".

The gear oil in the gearbox and the silicone viscous fluid in the centre diff are segregated and are not shared - not common.

The viscous coupling creates heat when it slips. The old Kilowatts (heat) equals torque (N.m) times rotational velocity (rad/sec).
Once the silicone viscous fluid gets above a particular temperature the fluid is cooked and the diff requires replacement.
They can last as little as 100,00km or go way past 250,000km, depending on how hard they have worked.

The cooked fluid becomes over viscous and causes the diff to "lock" when it gets up to heat (like RX25SE says).
So, requiring the diff to slip excessively due to mismatched or unevenly worn tires, or by higher power throughputs (WRX, H6 and GT Lib) for example, will result in centre diff failure.