3.4 S type diff oil leak

[Gosnell]

I have slight leak on the nose oil seal ( prop enters diff) can it be replaced in situ or is it a diff out job to replace the seal ?

Regards John

[PPV]

I presume it is the same as for the Mk2. It can be done as DIY if you can get the pinion flange (UJ flange)off. I bent a puller trying to get mine off and in the end had to get a friendly garage to use a hydraulic puller plus sume heat and it then came off. This was all done in situ. Once the flange was off the seal was then gently prised out. There is an oil slinger and a gasket to be removed and fitted also as these sit behind the seal. The diagram in the service manual shows these.
Be sure to mark the propshaft and pinion flange before removal to ensure correct alignment and fitting when putting back together for correct balance.
Best of luck,
Paul

[Martec]

As Paul says relatively easy to do in situ, but can I also suggest you mark the position of the nut on the input shaft and the depth from the end of the shaft to the nut top to ensure you refit the nut to the same place. Although the Sailsbury diff uses shims rather than a crush tube to set the crownwheel and pinion engagement, better safe than sorry.

I also had to change this seal and made a locking tool to hold the diff flange whilst undoing the nut (a metre long flatbar with two bolts welded onto it and a long bar on the socket). Unlike Paul my flange came off relatively easily (nothing was a slack fit). I seem to remember that the old seal was leather? and the new a double lipseal - rubber.

Best of luck

Brian

[oldtimer]

Hi All,
Just to add my peneth, It might be worth ensuring there is no obvious slack in the pinion bearing before changing the seal. Brian has of course raised the all important issue of returning the flange securing nut to it's original position which should be tightened to 120 - 130 lbs. ft. The pinion bearing is set up with a pre load of 8 to 12 lbs. ins. This is also called starting torque and measured with a spring balance but can only be carried out with the differential removed. It is certainly a relief that a crush tube is not used in this instant to get the correct starting torque.

Writing about this brings back a few memories - I still have some special distance pieces for setting the height of the pinion in the casing prior to introducing the diff back into place.

Oldtimer

[Gosnell]

Thanks for the reply's, the issue looks to be access as the S type is a fully independent rear suspension and the diff is held in a carriage.compared to the MK2 that has a beam and leaf spring suspension set up that looks as if access is good.

regards john

[stuarthardy]

Hi John

You are right, it is a much more involved process on the S type, due to the IRS. You need to remove the rear suspension unit, strip it down to gain access to the final drive unit and then almost completely dismantle the final drive unit just to change the pinion seal. The process requires the use of a press and special tools so is really quite involved and requires more than a little heavy lifting.

My advice is to buy a drip tray and keep the oil level topped up until the day it needs some major attention to the rear assembly. If its only a couple of drips a month then it really won't matter. If its a bit more than that then at least you'll be keeping clean fresh oil in the diff!

Like you, I don't like cars leaking their fluids but I think we can make allowances for their ages.

Regards
Stuart

[oldtimer]

Am I missing something - The fact that it is an S type with IRS makes no difference.
Jack the car , drop the prop shaft, pull the flange and change the seal. As the book says assembly is the reverse of the above. There you are job done , down the pub in the car for a pint.
Cheers

[stuarthardy]

There you go, John. Oldtimer's got it sorted for you.

Regards