Hi all,

Thought I'd start a new tiny topic.

I am driving my rusty Sigma again now we are heading towards the cooler months.
So the other day I thought that I really should check to see if the diff still has enough oil in it.
This because I don't remember ever checking it before.

I expected some kind of metal screw plug that would be easy to undo and hence a 5 minute job.
Instead there is a black rubber filler plug just above the axle centre line.

I tried gentle prying but the thing won't pop out.
Since its old and probably irreplaceble I left it alone.

Does anyone know if this rubber bung, on the inside, is flare locked or just a bit expanded?
My manual tells me nothing.

Yes, I remember that plug. Memory lane time!
Bugger to get out without damaging it. It's got an expanded end. I would get it warm - after a drive perhaps, and use a wide flat object like a steel ruler under the lip and then pull like mad. If it gets damaged, refill the diff and clean the mating surface where the plug sits and apply some silastic. Keep an eye on it afterwards.
Good luck.

If you don't want to risk it, does the diff have a rear cover you could remove and then push the plug out from the other side?

PS Yes, they do rust nicely, don't they? I miss the yearly cut and bog and paint treatment the ones I owned over the years needed. (I'm kidding) I think I had a GE, GH and a number of later models at one time or another.

Hi MadMax,

Glad someone even remembers the car let alone this crazy rubber plug.
Didn't think of getting this plug warm, so thats a good call.
You mentioning the silcone, gives me the idea that a nice round piece of metal can be silconed over the hole (now I have a backup plan)
Will have a look if there is a rear cover (no mention of it in the manual).

Mine is a GJ and I have had it since new.
The paint has completely oxidized, and in some areas, where it has disapeared all together, I've painted it with cold galvanising paint.
It now looks like a psychodelic - camouflaged box on four wheels (I know shocking dis-respect).

Every year I tell myself to just buy a new small car and then when I drive the sigma I postpone that thought.
Maybe this time if I break that rubber plug!

Thanks for the reply.

The diff has a bolted rear, into which this rubber plug is mounted.
I presume the idea is that you drain the diff by unbolting this rear end.

I think that this is probably what you meant by rear cover.

Draining/replacing is probably a good idea after 32 years.
But, like the plug, the gasket is probably not obtainable.
So would liquid gasket suffice in this application?

The diff has a bolted rear, into which this rubber plug is mounted.
I presume the idea is that you drain the diff by unbolting this rear end.

I think that this is probably what you meant by rear cover.

Draining/replacing is probably a good idea after 32 years.
But, like the plug, the gasket is probably not obtainable.
So would liquid gasket suffice in this application?

Probably a good idea to open it up just to wash the innards out. Engine degreaser sprayed in would do nicely.
I would remove the rear cover bolts and try to slice between the gasket and the cover. If you look closely at the joint, you may find it is glued to one part - diff housing or cover - which is standard procedure to keep it in place. If you use a thin flat blade like a Stanley knife, you may be able to keep the gasket in one piece, and reuse it with some liquid gasket. If it completely disintegrates, clean the two surfaces and cut a new gasket from gasket paper, or try using liquid gasket only.

I remember the Sigmas fondly. On several occasions, I'd buy a high km one for under $1K, then do the full treatment - engine recon, rust repair and repaint. Later, I found that the Magnas were a better deal, not needing a full engine recon at 200,000 km or less, so I kind of lost interest in the Sigmas. My hat off to you for keeping one running that long. Haven't seen a GJ on the road for ages.

You are right, taking off the cover seems the most sensible approach (I'll wait for a nice sunny weekend).

The Sigma has only 150K on the clock and still is all original except for the roof lining (it dropped off one hot summer!).
It has never let me down, but it is complaining with old age in all the usual manner (thirsty and all sorts of mounting noises).
Its 4 new tyres are the only shiny bits.

Have a Magna TP station wagon and a Verada KS as well. They too have some interesting issues.

Have a Magna TP station wagon and a Verada KS as well. They too have some interesting issues.

well the brain trust members on these two models is still around in 2014 ask away ..


you are right cant find a sigma genuine

Is this ..one anywhere near close to your sigma ?
http://www.ebay.com.au/itm/DIFF-OIL-FILLER-BUNG-PLUG-RUBBER-FALCON-XD-XE-XF-CORTINA-TC-TD-1-GENUINE-FORD-/261469384098?pt=AU_Car_Parts_Accessories&hash=item3ce0ca2da2&_uhb=1

http://www.ebay.com.au/itm/GENUINE-FORD-FALCON-CORTINA-F-SERIES-DIFF-FILLER-PLUG-BUNG-RUBBER-XD-XE-XF-TC-TD/121258276013?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222003%26algo%3DSIC.FIT%26ao%3D1%2 6asc%3D20140106155344%26meid%3D6857616523252119878 %26pid%3D100005%26prg%3D20140106155344%26rk%3D1%26 rkt%3D6%26sd%3D261469384098&rt=nc

Those are the right plugs by the looks of them.
IIRC Borg-Warner made diffs and manual gearboxes for the Sigma and other local makes back in those days. The rear diff plate was stamped out of thin metal, hence no thickness for a proper threaded plug - consequently, the rubber bung.

Correct were Borg Warner and most of the plugs for these were all the same, should not be a big issue to get a replacement.

Sealant will nto last long so try and get a proper plug

That certainly looks like the rubber plug, I'll order one just in case.
Seems everytime I want to work on my cars something more urgent comes along.

That said I now have a new head lamp problem that I have to give a high fix priority.
Will start a new thread on that.

Just coming back to this little job.
I asked the ebay vendors if those filler plugs (rubber bungs) would fit the sigma differential.
Resopnse was that it fits only the diffs on the mentioned vehicles "FORD FALCON CORTINA F-SERIES XD XE XF TC TD".

I can't find them listed anywhere for the Sigma.
I'll still order one and hope it fits, if the old one breaks (hope Madmagna is right that these are all the same!).

I do really just want to check if there is oil in there after 34 years (it sounds fine!).

that ford plug is the only types left available and being produced ...

so make it fit there

hmm 34 years huh
..they must have used castrol way back then in borg diffs

oils aint oils ------
the castrol gtx series of commercials from the late 70's to the mid 80's
https://www.youtube.com/watch?v=pE_HbVs3bCM

So true "oils aint oils".
Wouldn't you know it, I remember that ad very well (and always bought castrol GTX!).

Who knows what was put in that diff!
Never ever seen a drop of oil under the diff though.
Everytime looking for leaks I remind myself to have peek inside this diff.
Then I just drive the old beast and forget.

Asked the guys at a local specialist diff centre, and they said that the rubber bungs are the same.
They still use them regularly.
Only $4 each from them, so got a couple.
Ready to take a peek to see what is left after 34 years! (presumably it still has enough in there else the diff would be - stuffed!).

So with the new bungs in hand, I was able to make a simple tool (from an old antenna mounting!) to help lever the old plug out.
Not actually tried it as yet!

http://i.imgur.com/bh52HHG.jpg
http://i.imgur.com/O5Pd2r1.jpg

didnt know you could fabricate and weld so well

Can't take credit for the nice weld.
Originally a mount for a small UHF antenna (I think!) and the pole to bracket was already welded nicely.
Just chopped of most of the pole and re-purposed the bracket (bracket was a U with 2 bolts on one side to secure it onto something "gutter!") .

It was another case off - 3 hours to make the tool and 1 minute to apply it.

I call that fabricating .. I have a few fabricated tools in my tool box

Cant wait to see the picture of the diff oil after 34 years:ninja:

Cant wait to see the picture of the diff oil after 34 years:ninja:

Probably solidified into a big black solid blob by now. It will need some flushing with solvent to get it all out.
Remember the diff oil is also meant to lubricate the rear wheel bearings. I'd pull the axles to check how the bearings are going, then pour petrol through the openings to wash out the grot in there, or run a petrol soaked rag through there. (on a piece of wire, so you can pull it out again and it doesn't end up stuck in there. lol)

I'll let everyone know how it looks.:facepalm

Expect there to be a thick viscous oil in there as I've not noticed any issues with wheel bearings or diff noise.
The curiousity will be "how much is left in there".
I am thinking this is more a case of the lubricant being degraded with KM's done rather than with the passing of time.

If MadMax is right, then this will be a bigger job then I anticipated.
Hopefully not as I just intended to pump out the old oil and replace it.

The tool worked a treat as it levered the filler plug off in one easy action!

I was surprised that the filler plug was still very pliable and feel confident its still re-useable after 34 years on the diff.
Also was surprised that the diff had most of the oil still in it (maybe about 80%).

The oil in there is very thick (as it should be for SAE-90) and was simply black.
It won't syphon out by gravity alone. Tried to suck some out into a plastic container, with vacuum pump assistance, but no go (simply collapsed the container!).
Got about a jam jars worth of oil out, got fed up with it and decided I need a better oil pump.

So I filled it back up with new oil until it overflowed through the filler hole (used about 700 ml).
The new stuff also just wouldn't flow through a plastic hose into the diff (even from a 2 metre height!).
Instead I used a large (60 ml) syringe to squirt the oil back in (a fair DIY solution!).

Anyway, at least I now know the diff has oil in it!!!
Should I post a picture of the black syrup in a jar????

yes a picture please

Some pictures of the 34 year old Diff Oil.

http://i.imgur.com/GoYEMCQ.jpg
http://i.imgur.com/MS2QXl0.jpg
http://i.imgur.com/MaofuXJ.jpg

The last picture (blot test) shows that the particulates are left behind as the oil wicks through the paper.

No idea why the oil has black colloidal particles in it.
Hard to believe its from gear wear and tear or breakdown of viscosity additives.
Kind of looks like a tube of molybond was added to the oil.

Simple!
That oil is so old, it is returning back to it's original state - dinosaur droppings!

Personally, I would have given that diff, the housing and the axle tubes a good washout. The rear wheel bearings have been running in that goop!

@ MadMax - them dinosaurs need a better diet.

Sometimes its a case of, if it ain't broke don't fix it.
Bought a suction gun at SCA (just a big syringe really!) and will flush a couple of litres of new oil through that diff with a bit of usage in between.
Agreed its not a proper job but just a quick bit of TLC for the old beast.