Weeping Oil Seals

[richard btype]

Can there be anything more disheartening than removing a major component (diff, gearbox, engine) replacing oil seals only to discover a short while later some weeping?

How can one be sure before all the reassembly that the work has been successfully accomplished?

For example if one fits a new seal to an old input/output shaft the risk is high and therefore to replace i/oput shafts is a pre requisite?[/b]

[David Oslo]

Or install a SKF Speedi Sleeve on the part of the input (output) shaft that is in contact with the new seal. That's what I've done on the input shaft on my gearbox given that I had some concerns that the micro marking I saw would end up in a leak.

[richard btype]

David

Very interesting, were you happy that the dimensions of their catalogued items matched your requirement or did you have to order specials?

[David Oslo]

Catalogue item matched just fine.

[Skylink]

I recently had a leaking rear gearbox black Nitrile seal, which was fitted only 2 years ago. I replaced it with a Viton seal, which can withstand much higher temperatures and gases.

[PeterCrespin]

I recently had a leaking rear gearbox black Nitrile seal, which was fitted only 2 years ago. I replaced it with a Viton seal, which can withstand much higher temperatures and gases.

What temp and pressure do you think the tail of a sound gearbox reaches? Nitrile is fine. Still, after 'recently' has become '2 years ago' you'll be able to compare. The Viton will probably be slightly better if the surface is very smooth and gets wetted with oil.

[Skylink]

It has been proved that certain fumes an gases degrade Nitrile. When I removed the Nitrile seal there was several cracks with a burned appearance where the seal was in contact with the shaft.

[PeterCrespin]

Well there should be no pressure as the box is vented, which leaves chemical attack.

Many gear oils have sulphur species in them, which can be quite reactive and may be the culprit?

However, the point remains, surely, that if there were a fundamental incompatibility or vulnerability leading to nitrile failure after two years, every five or ten year old car ought to be leaking like a sieve? My 24 tear old Buick is as dry as a bone.

Nah, I can accept Viton is more stable and I can accept nitrile is not immune to all chemicals or persistebt running at much above boiling point such that failure of, say, valve stem seals is inevitable eventually. But blaming a seal an isolated failure at two years on the near-universal choice of nitrile rubber seal material is a bit of a stretch...

Be nice to see the refs though.

Pete

[PeterCrespin]

Well there should be no pressure as the box is vented, which leaves chemical attack.

Many gear oils have sulphur species in them, which can be quite reactive and may be the culprit?

However, the point remains, surely, that if there were a fundamental incompatibility or vulnerability leading to nitrile failure after two years, most five or ten year old cars ought to be leaking like a sieve? My 24 year old Buick is as dry as a bone and I suspect is cheaper nitrile almost everywhere. .

Nah, I can accept Viton is more stable and I can accept nitrile is not immune to all chemicals or persistebt running at much above boiling point - such that failure of, say, valve stem seals is inevitable eventually. But blaming an isolated seal failure at two years on the near-universal choice of nitrile rubber is a bit of a stretch...

Be nice to see the refs though.

Pete

[Skylink]

From reports available on the net, Nitrile is subject to degredation from certain hydrocarbons associated with oil products.
Firstly I had the gearbox seal go after two years and now I have an inlet stem seal gone. Full engine re build 2 years ago.
Spoke to jaguar specialist engine re builder in Coventry, who has had several Nitrile seals going bad after recent re builds.
He said it could be the oil or the quality of the Nitrile that is at fault.
In any event, I would not use Nitrile again if there is a better quality elastomer on the market.