Warning Around Jimny JB74 Transfer Box Chain Replacement

I have already posted that my Jimny JB74 seems to have a leaking oil seal on the transfer box rear output shaft. The car has only travelled 37,000 gentle miles in 4.5 years with no off-road use. My feeling is that this oil seal failure is rather premature.
At first I thought that it might have been triggered by dropping the fuel tank recently to carry out the fuel pump replacement following a recall. However, topping up the transfer box oil today I needed to add 300ml so it is unlikely that the fuel tank work, carried out 9 days ago, is responsible.
Therefore it is possible that the work to replace the transfer box chain, performed under warranty, probably 3 years ago, has led to this failure.
Now, I have no agenda to push here. When I find the time, in the next few days I will replace the seal. I bear no grudge against the dealer or Suzuki. Stuff happens. I would suggest, though that any owner who has had the transfer box chain replacement carried out check for a leak. Even a tiny leak can empty out the transfer box oil sufficiently to eventually cause a mechanical failure.
It would be interesting to hear of any other similar leaks on the JB74.
Thank you.

I would guess that, for many Suzuki dealers, it would be the first time they'd ever done the job.  Gen4 Jimnys are not exactly common.

Does anyone have details of the chassis numbers that apply to this recall?

Cheers

Roger

It's not a recall, it's a "replace on fail" so applies when reported

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I would not be to worried about this at all. I Work with Marine gearboxes and see that sometimes these lip seals fail sooner, and sometimes later.. The service life varies very much depending on the cleanliness around the seal and underneath a car is not a very good environment.
There is not much to be done to prolong the life of a seal other than cleanliness, the quality of the seal, pressure and rpm.
Based on experience, pressure washing may do as much harm to the seals as no washing.
Some seals have never failed on my cars but others fail all the time.
I do not worry so much, my car gets all the wrong treatment like submerging in mud and sand and water and pressure washing after.

One important thing is the pressure inside the seal/ gear box. I have noticed that on my rear axle when the breather was caked and rusted shut, the seals gave in sooner than normal. Just as suppliers say. There is a calculated factor for seal life that is a product from pressure difference inside/outside and rotational speed.
Failing seals is normal within a few years of service, some just fail more often than others.

Good info Dr Chris, thanks for posting.

I for one am pleased that I lived long enough to see the day when a leaking gearbox seal is a wild statistical outlier.  

But seriously, it sometimes happens that a seal starts to leak when disturbed, or a new seal doesn't seat quite properly, or as Yakuza says, a seal just doesn't have the fortitude that its fellows have. And even the very best seals will leak a tiny bit.  I think Dr Chris has the right attitude -- no need for blame, just bung in a new seal and keep on.

Though with 4 years and not a single mile off-road, it could be that the Jimny simply misses its natural environment. Time to go out and get some mud on it.

There's an old engineering maxim that "for a seal to seal, it has to leak".  What this means is that there has to be some lubrication of the seal lip, or it quickly burns/gets torn and creates clearance and a real leak.  Single lip seals are always a bit of a compromise in this respect.

Actually if the axle is too polished there is no way for the new seal to Micro grind the tip of the lip to the surface and less likely a good lubrication. there could also be Micro grooves in a spiral form in the correct pattern depending on the direction of rotation, to transport oil on the lip surface, back in to the inside of the seal.
But now it is getting nerdy