So where's the oil coming from?

Ventodue

Ventodue

Hero member
Location
France
Ok, this is for a Zan? 750 Formula, so all you Breganze-only boys can look away now ... :P

I've got a slow but irritating oil leak from behind the gear box sprocket/clutch piston cover. But I'm not sure exactly where it's coming from, so any thoughts much appreciated.  Here's a photo that may help:

Clutchcoveroilleak.jpg


Obviously this is with the cover itself removed.  On the left side you can see the gearbox shaft - I've removed the gearbox sprocket.  To the right is the entry to the tunnel for the clutch push rod - I've removed the external support bracket.  Up slightly and further to the right is the slot in the casing for the cable for the neutral indicator switch - the cable is folded up out of the way, into the slot.

And, as indicated, the oil drips out of the tube at the bottom.

Seems to me there's 3 possible sources:
1.  The seal on the gearbox shaft.  But this part was actually quite dry - certainly not dripping in oil.  And anyway, how would any oil get from the sprocket area to where it leaks out?

2.  The seal on the clutch push rod mechanism.  Originally, I thought this was a seal to stop water and stuff getting IN.  But in the photo you can see that there's some oil on the push rod that's showing just past the seal.  So am I wrong, i.e. there's oil inside this tunnel?

3.  I'm also a little suspicious about the slot in the casing for the gear indicator cable.  I can't now remember, but doesn't this connect with where all the starter gears are splashing about in engine oil?

As I said, any thoughts appreciated.

Ciao

Craig
 
An old motor trade trick is to dry EVERYTHING off put some talcum powder in your hand and blow it onto the suspected leak area.... Run the motor and reassess.

    Best of Luck

                Tim
 
Craig,

It's usually the neutral light switch.  These are the same as used in the Breganze bikes and are notoriuosly leaky.

piet
 
if it's the Neutral switch, you can either seal it with some epoxy glue or replace it with a new one from Motalia (roughly 40? meanwhile...). They should have hundreds (if not thousands...) left over from a re-production run they did roughly 8 years ago or so.

Better buy sooner than later, they are adding storage costs every year to the price... ???
 
Thanks guys.  I didn't give the neutral light switch more than a passing thought, Piet.  I'll go have a closer look.

And try Tim's trick ...  ;)

More later.

Craig
 
Well, I've just run the engine up for 5 minutes or so and guess what?  No leak, dry as a bone ...

So I guess either I'm looking in the wrong place; or it only leaks under load.  Which would probably point to the seal on the driveshaft?

Ciao

Craig

(Btw, the neutral indicator switch is different from the Breganze ones.  Looks like this:

Neutralswitch.jpg


The parts book lists the Breganze type for the S model; but a different one - presumably this one, but there's no illustration - for the Formula.)

 
Ventodue said:
Well, I've just run the engine up for 5 minutes or so and guess what?  No leak, dry as a bone ...
Click to expand...

might be it's just happening when the oil is hot or it just happens in 1st gear or while shifting? Do you have a proper bike stand for the rear? if so, you could try to shift the gears through by hand (works also without clutch if you push just gently on the shifter lever and wait until the gear "snaps" in, but is not good for the gearbox... ). If that's not doing it (or to start with) you could also hold the bike a bit to the right side to see if it's maybe coming through the hole where the clutch push-rod goes through.

I agree, the neutral switch here looks different to the one of the Breganzes. if its not a 10mm but a 8mm (I think) thread, you (and me...) are lucky, as these are readily available from other brands...
 
Hi Craig

I have never had my hands on a Zane era Laverda as Canada wouldn't let them in, and still won't, until they reach the 15 year age exemption......

anyway, at least on a Breganze era Laverda that gear box output shaft oil seal is quick and easy to replace. Insert a sheet metal screw or two into the seal, and pull it out with a couple of pairs of pliers, one on each screw head. On the Breganze era bikes they just pop right out. Install the new seal with a large deep socket as a seal driver.

there shouldn't be any oil available to come out of the clutch actuating push rod shaft tunnel, it isn't typically oil lubricated on most bikes, that seal is usualy just a dust seal to keep crap out of the tunnel so the push rod can conitue to actuate smoothly.

Paul LeClair
 
Thanks guys.

@ Lothar: yep, all good points.  Will try further tests, e.g. with warm(er) oil; shifting; and leant over.
(P.s Yes, the switch does look rather worryingly like another cheap Ducrappi left-over ... :o)

@ Paul: I suspect you're right - the seal is part #29 below, can't see why it shouldn't just be a conventional pull out/push in fit:

Mainshaftoilseal.jpg


I just don't want to start something that then leads to something that ... you know.    The bike is at least up and running at the mo'. (No sizes in the parts book, neither.  So will have to get my magnifying glass out before I destroy the old one).

And thanks for your confirmation about the absence of any oil lubrication in the clutch push rod tunnel.  Suggests the oil is either coming past the main shaft seal, or down the cable slot ...

P.s.  Time is passing - a few more years and you'll be able to buy this one !
 
As in most Laverda engines, the clutch push rod goes through one of the gearbox shafts on the Zanes.

A small amount of leakage can be expected if the seal wears.

piet
 
sfcpiet said:
As in most Laverda engines, the clutch push rod goes through one of the gearbox shafts on the Zanes.
Click to expand...
Thanks Piet.
(Coincidentally, I worked that out last night when I read this in the workshop manual, page 103: "This (clutch) pinion pushes a central rod, inserted in the gearbox primary shaft ...)".

sfcpiet said:
A small amount of leakage can be expected if the seal wears.
Click to expand...
Ok, that helps.  I reckon the seal could have suffered 'cos the first clutch push rod has some corrosion just about where it goes thru the seal.

Clutchpushrod003a.jpg


Right, time to change both seals.  I'll get on to Dirk and see what he can supply.

Thanks again to everyone.  It will be good to be finished with this leak, after XXX (I won't say how many!) years!

Ciao

Craig
 
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