Rear Diff Oil

[Dad]

1966 Series 1 FHC 4.2

I took the IRS out and replaced the brake pistons with Coopercraft.

I openly admit to not knowing a massive amount about my car (I inherited it and am working to develop knowledge/ability in taking care of it).

I tilted the IRS on its axle stands to access the brake pistons and spent a good few days working on them (I'm the guy who sheared a bolt and posted a request for advice in getting it out). During this time, I used a bucket against which to tilt the IRS into position.

Reason I mention the bucket is because the oil from the diff seems to have drained into it without me knowing. If the bucket hadn't been there, I would have quickly seen the leak and realized what was going on.

So, my question is;

What type of oil do I use and how do I get it in there?

I have hit the books I've got and done some online research but, oddly, can find hardly anything on this.

[Heuer]

You need LS80w-90 limited slip gear oil from any of the major manufacturers. Drain the diff first using the square bolt head on the bottom the case, replace, remove the filler bolt on the rear of the casing. You can then refill to the level of the hole. If the diff is in the car you use the long snout on the oil bottle to squirt the oil in.

My only question is how on earth did the diff oil drain out if you have not removed either of those plugs?

[Dad]

I think it must have leaked out of the L bend plastic pipe (breather?) on the back side of the diff.

[Heuer]

Ahh - OK. Make sure that pipe is not blocked or damaged though otherwise the pressure will build and force out oil through the half shaft seals. As regards oil you can use something like this:
http://tinyurl.com/p9dw9yb
or if you want something more advanced and very expensive, this:
http://tinyurl.com/pjsjfdd

You will need 1.6 litres, so two bottles.

[Dad]

That's great - thanks!

[Dad]

So, the 'filler and level plug' referenced in the attachment you added is the plastic L tube sticking out that rear of the diff?

[Heuer]

Forgot to say I use Carlube/Castrol/Mobil LS80w90 rather than the Red Line stuff in the diff. However when it comes to the gearbox you will find Red Line MT90 is superb for the Jaguar all synchro box. Red Line MTL transforms the Moss box.

[Heuer]

So, the 'filler and level plug' referenced in the attachment you added is the plastic L tube sticking out that rear of the diff?

No, the breather is a separate part:


Filler is #5. Parts 7, 7A and 8 make up the breather on the 4.2 cars. It must be working so take it off and blow through it to confirm if you are in any doubt.

[Durango2k]

..and be carefull with them, the elbow just fell off in PARTS on my diff on the bench. Strange.

But SNG has them at 6 pounds, so...

Carsten

[Dad]

Great - thanks. Last question (I promise). Before I buy, approximately how much will I need?

[Heuer]

Already answered a few post's earlier but 1.6 litres, so two bottles. Did I mention you need to make sure it is suitable for a LSD diff? - the oil contains special additives to keep the friction plates working correctly.

[Moeregaard]

Great - thanks. Last question (I promise). Before I buy, approximately how much will I need?

1.6 litres/3-1/4 U.S. pints/2-3/4 Imperial pints. As David says, use the LS80w90 oil in the differential. Your limited-slip clutches will thank you :D

[johnney]

What type of oil do I use and how do I get it in there?

I have hit the books I've got and done some online research but, oddly, can find hardly anything on this.

For a list of Jaguar recommended lubricants (oils and grease's), lift the bonnet and take a look at the data plate riveted to the top of the right side inner sill underneath the fuel filter. Although it doesn't mention as did David before, that the diff oil should be an LS type.

[rfs1957]

Has anyone ever found a decent tool to grip the square-headed filler plug ? I've had this down on my list of Nasty Operations That Require A Better Tool for years, and damage the plug a bit more each time I grapple with it, but never seen a square 9/16 or 14mm socket or w.h.y. that would help. Or is there a suitable hex-headed plug (male or female) available from some other application that would replace it ? Ideas most welcome.

[Heuer]

You need a 5/8" eight point socket rather than the traditional 6/12 point. You can buy a set of them from eBay for not very much. They are also great for those square head drain plugs on central heating or water taps.

[johnney]

This is what I use, an 8 point socket. You can also change the plugs for Allen key type which are much easer to remove and replace.

http://www.ebay.co.uk/itm/SNAP-1-2-DRV- ... 1126726056

[Heuer]

Oddly the 8 point sets are hard to find in Europe but very popular in the States. Here is a Craftsman set of 5 for about ?5 (but check the set has a socket size for the diff nut): http://tinyurl.com/ns5yl3j

[rfs1957]

Thanks, that Craftsman set stops at 1/2" but I get the point, never seen these before. Anyone got a source for an allen-headed equivalent plug ?

[johnney]

http://www.ebay.co.uk/itm/3-8-Bsp-Male- ... 19cfce8afb

Check its 3/8" before ordering though !

[Robert Hiland]

I might be a bit late with this response but you could try a 1/2" universal for your 1/2 " drive. It also solves the problem of getting around the exhaust and IRS cage.

Other tips:
-purchase a manual oil pump used for marine lower units
-make sure the car is level