Transfer Box Oilseal Leaking. But Why??

[swampy]

Hi all,
I seem to have developed a leaky front oil seal on my Gen 3 Transfer box front oil seal. Seen one or two threads on here regarding changing it.
I sourced one from RoughTrax 4x4, a couple of weeks ago with the intention of having a go when the weather improved a bit.
However the truck had it's mot last week, and passed, (yippee!!), moving on, I asked if the garage fancied doing the seal for me, as it's got to be a pretty straight forward job with a ramp.
Answer was, "ah, but WHY is it leaking, that's what we should be looking at to begin with, those sort of things don't go very often and for no reason, maybe the bearings are breaking down and wobbling!"
Question is, has anybody experienced seal failures and replaced them, only to find that within a short space of time, they've gone again?
I'd be gratefull for any theories, other than the garage wants me to spend quite a bit of wonga!
(I don't green lane or off road, don't use 4 wheel drive much, only snow and mud etc.) Does the transfer box suffer the same breather problem as the diffs corroding up for instance, I can't find the transfer box breather.?

[knicko]

When I had to change my leaky seal it was apparent that my T case had sucked in water (presumably driven through deep water by previous owner?) as the diff oil within it was mayonnaise like. If you look inside the new seal you will see a metal spring that holds the inner edge of the seal onto the output shaft. In my case this spring was so rusty it had snapped....causing the oil leak past the inner edge. Could be case with yours?
Worth doing front and back seals (note - they are different) at same time as not expensive.

[swampy]

Sounds like a good idea to do both at the same time, never thought of that, I'll get one ordered up and give it a go and see what develops. How were the bolts/nuts? for undoing, mine look like they have never been disturbed since new, trouble with rolling about on the floor, you can't get the same leverage?
The rusty spring sounds feasable, but I've not checked the oil out yet, so time will tell.Cheers.

[knicko]

The nuts holding the flanges to the output shafts are very tight and have one edge peened into the shaft, which needs chiselling out so the nut can undo. The nuts are 30mm by the way.

Very important is to put these nuts back in same position so count the turns off and ensure same number of turns back on when refitting. The peened nut will help make it obvious what position you are aiming for as it will line up with the recess in the shaft.

I would recommend you try to do this job on ramps as you need a long bar to get the nuts cracked and there isn't really enough room by just crawling underneath.

Good luck