Clutch oil seal and sleeve gear bush

[Phil C]

Hmmm... don't like the sound of that. So I should drain the pc, remove the clutch adjustment plug screw, start the engine, and put my thumb over the hole? Is that right?
Is the crankshaft seal a big job for someone like me?
Thanks again for your help.  Phil

[Phil C]

Further to my post just now, when I drained the pc the other day there was 1/2 pint in there, to my surprise. I couldn't understand how I could have put that much in. Phil

[AWJDThumper]

Do the test and it should be obvious if the crankshaft seal is blowing. It's not a big job to replace - just need to remove the alternator to get at it. If you put the correct amount of oil in to start with and it then ended up with 1/2 pint then a leaking seal could well explain it!

[Phil C]

Excuse my dimness please, AWJDThumper: you say it should be obvious if the crankshaft seal is blowing. Obvious in what way? Phil

[AWJDThumper]

The engine will generate pressure pulses (puffs of air) which you should feel coming out of the chaincase hole

[Phil C]

Update: just now I drained the pc, removed the clutch adjustment screw, started the engine, and placed my fingers at the hole  (loosely, as it's quite a big hole to completely block.) I didn't feel any puffing. Does that rule out the crankcase seal ( despite the overfull pc mystery)?  Phil

[DAVE BRADY]

Good afternoon Phil,

I have copied and attached your image of the leak/drip.  This reminds me of a similar issue on my wife's '51 Flash.  The problem turned out to be the gearbox oil seal behind the sprocket although a leak around the layshaft bush, as has been mentioned, could produce a drip in the same place.
The drip appears to be on the bottom of the gearbox and to be in this location is unlikely to have come from the primary case or the main shaft bush seal as this drip has almost certainly emanated from behind the sprocket.
I think that you said that you replaced the gearbox seal not that long ago so the seal has either failed prematurely or oil is finding its way past where the seal sits in the case - this is not unusual. 
Perhaps a plan of action could be to remove the clutch and the sprocket to see if oil is seeping past the edge of the seal where it sits in the case.  Two options come from this.  Either remove the seal and refit the used seal after a thorough cleaning and the application of a bit of silicon where the seal sits against the case or do the same but fit a new seal to save having to do it again later.

Dave.

[AWJDThumper]

Update: just now I drained the pc, removed the clutch adjustment screw, started the engine, and placed my fingers at the hole  (loosely, as it's quite a big hole to completely block.) I didn't feel any puffing. Does that rule out the crankcase seal ( despite the overfull pc mystery)?  Phil

It should do but, if you find excess oil in the chaincase again, it might need revisiting!

[Phil C]

Thanks Dave. But I'm finding it hard to believe the leak is gear oil, given that when I drained the primary chaincase (pc) and then went for a short ride, when I got home there was then no sign of a leak.That suggested strongly to me that the leak was from the pc. I'm going to try it again with s bit longer ride. If when I get home there is no sign of a leak then surely it must be coming from the pc? Do you see, on the photo, the vertical dribbles down the chaincase wall?  Phil

[DAVE BRADY]

Hi Phil,

Yes and I see that you did mention that you had wiped some oil off so less evident.  Perhaps then remove the clutch etc. and do as suggested but also revisit the seal in the plate behind the clutch as well.
If it looks like the layshaft bush is seeping a bit of oil, there is a product that can effect a cure.
Oyltite Stik is rubbed in to the offending joint/seam and dries to cure the leak.
I got mine from www.frost.co.uk

Dave.

[Phil C]

Good morning all. Well, not so good here really so far. Having drained the pc (with bike on side stand), this morning I went for a ride - just a few miles. When I got back I eagerly peered under the bike, expecting to see no sign of a leak. No sign of a leak will confirm the leak is from the pc, I thought to myself. I was almost confident.  But, alas, the tell-tale dribbles were there.  Not a lot, but definitely present (see photos.) So the source(s) of the leak is/are still a mystery.  My oil dye has arrived this morning, so I guess I'll refill the pc with oil + dye, go for a ride, and have another look.   I guess there might be more than one source. 

There is a leak at the tap on my oil feed pipe, which runs down the rubber pipe, but I don't think that is relevant to this.

Any thoughts please?

Phil.

[Phil C]

Further to my post from earlier, maybe I should put the dye not in the pc but in the gearbox? The dye is the stuff from demontweeks, via the link kindly provided by AWJDT.   It says it's for engine oils and fuel, so hopefully would be suitable. I would love to solve this mystery and stop the leak.
Phil

[AWJDThumper]

It's difficult to see the oil in the pics but I assume it is the multiple brown streaks on the back of the chaincase? If so, it looks as though it is running down from around the rear cover plate joint - it may not be leaking from there but is running down on to this joint before spreading?

I would definitely advise putting the dye into the gearbox - that's probably where the leaks coming from but, if not, it would be good to rule it out. It should be much easier to solve a chaincase leak!

[Phil C]

Thanks for sticking with me on this. You might remember that this morning, after a ride with an emptied pc, there was a dribble.  Here is the latest:  this afternoon I refilled the pc, put dye in the gearbox, and took the bike out for a ride. When I got back, this is what I saw. You can see a dribble again, but it doesn't look to me as though it has dye in it. To me, this doesn't make sense.  And I imagine you're running out of things to suggest?  Phil

[AWJDThumper]

Any chance of adding some graphics to the picture (eg using MS Paint) to highlight where the oil can be seen? If I were to guess, it looks as though it is running down the back of the chaincase to a drip underneath the suspicious looking hole that can seen towards the bottom of the chaincase! There also looks to be a brown stain from the cover plate to the same hole but it's difficult to tell whether this is oil?