oil leak from swing arm gaiter - T3

I recently got my t3 cali back on the road and after a few hundered miles of trouble free riding noticed i had oil on back wheel (a few drops) and some minor leakage around the swingarm output shaft rubber boot.

I solved the leak from the bevel drive replacing the inner oil seal and as i had swing arm off also replaced the oil seal on output shaft.

Still getting small amount of leakage after riding from boot.

Has anybody any ideas what problem might be. I did check level of oil in gearbox i am thinking I over filled as oil pours out the inspection plug which I think the level should be just to lower lip.

Could the oil leak be happening do to being a bit tooo generous on gearbox oil.

Not affecting me riding bike but would prefer to fix this.

Any help appreciated


I would take the level plug out and leave for 1 hour then refit plug take for good hard run and while hot BURP the rear box that is remove the ffiller plug to release the pressure then refit it that cures a lot of bevel box drips , is the oil on the gaitor out the rear bevel or the gearbox (Thick or thin) if you have overfilled it it can work its way up to the gaitor

Should not be any oil out of gaiter A. it’s supposed to be a good seal at both ends anyway B. there should only be grease in there and even then just for the spline. Yes Deffo drain down to the level plug as said. Gearbox has a breather hose so shouldn’t be pressurising. Unless said hose is blocked or something. On early models it connects to the dedent plunger for some reason I can’t remember. Later ones just have a plain union screwed into the casing.

What I forgot say was are you sure it’s gaiter and not somewhere else so only looks like that’s where it’s coming from, as oil leaks often travel about, just to confuse things.

I will drain down and take for run as you suggest and let you know if any improvement. I am pretty sure it is leaking from around gaiter.

To borrow a quirkily translated question from the MG workshop manual, does this oil ‘smell bad’ (is gearbox oil) or doesn’t (is engine oil).

Well the only oil in that area should be either from the gearbox or bevel box …yes it can blow up that far …BOTH are HYPOY gear oil so will have that gearbox oil smell

Well it doesn’t normally travel back up the tube from the bevel box, even though there is no seal there on the Tonti models.Overfilling the gearbox of course…

Also and as well as, there’s a sealed bearing in the way which the rear UJ boss is mounted in, unless the boss is well sloppy and loose Only other poss is g/box o/p seal is shot. I’d just like to be sure it isn’t from somewhere else and simply running or blown back onto the gaiter. Waiting on Willy…

Yes, I’d forgotten about the support bearing.

undo the gaiter and have a look see, also check that gaiter ain’t split. In my experience the seal is usualy the issue (whether wear and tear or pressure) but you may find that, once you clean it out (it only visibly leaks when it is full up!), you’ll get away with it a little while longer before needing a change - which is easy to do. Also need to discount blocked breather as per earlier comments

Still waiting on Willy…

In the original post, he did say he had replaced the oil seal on the output shaft.

I solved the leak from the bevel drive replacing the inner oil seal and as i had swing arm off also replaced the oil seal on output shaft.
I assume this would be referring to the gearbox output to the UJ so either the new seal has failed or it is down to overfilling the gearbox.

Yeah but no but, if g/box seal is working, it still couldn’t get out even if overfilled?

Confronted with much oil when I stripped the S3 yesterday; gearbox oil all way down shaft, but been hidden from view by effective gaitor! Output seal was in good nick…but not sitting in place!! Only a single lip seal so will replace with dual as all my other ones. UJ was loose in support bearing so that is probably how oil got all way down shaft. Strangely enough, level oil in gearbox was not particularly low which must explain how I missed it.

Still waiting on Willy…