Oil Leak, Help diagnosis and what to replace

[DuranMendoza]

Hi,

I have looked through all the threads regarding oil leaks and I couldn't specifically find what I should be doing, so I wanted to put this out there.

I took the bike for a 30 min ride, and when I came home the rear tire was coated in oil, chain was shiny as I believe it was covered in an engine oil leak. The breather had a few drops of oil, so I am assuming that the line was clean and that it allowed for breathing without being blocked.

I have since pulled off the side cover to show what I am seeing. I am assuming that there is an oil leak coming back from behind the front sprocket, however there was some oil pooling under the selector drum. I have cleaned it up a bit so it doesn't look as bad as the amount of oil that was leaking. Its was quite a bit.

So a couple of questions:
1. Do I need to replace the bearing and washer internal to the case? (Items 5 & 6) on the attached drawing. Does this mean that I will need to fully disassemble the engine to resolve this?
2. Can I simply replace the Sprocket and washer (Items 38 & 30) on the other drawing? I have heard that Lacey Ducati sells the sprocket with the oil thrower, and I don't know if this helps?
3. Am I completely missing the problem? In which case I am all ears.

Thank you all,

Duran

[Duccout]

You need to ascertain if the leak is from the selector shaft or from behind the sprocket. From the pictures it looks like it is from the selector shaft, but oil gets everywhere!

[blethermaskite]

de grease everything in the area of the selector drum shaft, clutch arm and sprocket, remove the chain, refit the selector box cover, put the bike on the centre stand and start it, select second gear and run the engine at 2000 rpm for a few minutes (don't let it get overheated!) do a few gear changes and clutch actuations, stop the bike and remove the gear change cover......now see what oil escape you can see ......from your picture I suspect the gearbox output shaft/sprocket area, if everything was drowned in oil after a 30min run the above process should show up where the oil is escaping in a few minutes.
PS is the oil level correct in the engine , not overfilled?
Cheers,
George

[ranton_rambler]

Don’t forget there’s also the clutch pushrod.
Some people use a bit of talc to help find leaks as it sticks to the oil.

[Jordan]

I haven't had the problem with my singles, but my 750GT developed an oil leak from the sprocket area.
The solution was to remove sprocket nut, which was retained by a bent washer but was a little loose, and sprocket, spacers, etc.
Then cleaned it all well with petrol and let it dry.
Applied a little silicone sealant to all the faces of the removed parts, reinstalled and tightened the nut well.
It worked. The reason is that oil can escape if the nut is loose. Silicone was optional I guess.
May be a similar situation with singles?

[DuranMendoza]

Hi everyone. Thanks for the help

So I did as followed. Took the chain off, reassembled the case back together. I a started the bike, and ran it for about 10 min shifting through all the gears up and down twice. After all of that I removed the side case again to check for a leak and I saw nothing. Not a drop.

I don't know if this is because it was on the center stand and has a forward tilt?

When I changed the oil initially I put in 2.75 Qt. When I check the oil today it looks low on the dip stick, but I am afraid that maybe the problem was over filling with oil? I am not sure because again showing low on the dip stick.

Any thoughts? This was a picture of the inside after removing the case.

[blethermaskite]

Ok so while you now have the chain of....put a lever between the sprocket and the engine casing and (gently) try to lever the sprocket up and down .....this will give you a sense of how worn the bearing behind the sprocket may be, you really should'nt get any movement, but if you do the oil sealing capability of that bearing will be compromised, this may well only show up as a leak when the chain is on and constantly tugging at the sprocket while riding,
I would take it out for another road run now its all cleaned up maybe 10/15 miles and then have another look to see where the oil is getting out from,
Are you sure the engine breather is clear?...does it terminate as an open end pipe or is it going into the side/air box? the breather in the air box type may terminate in an odd little rubber flap valve assembly, when its old the rubber can go rock hard and tends to significantly block the breather.
Is the engine putting out any blue smoke ?
Its all a matter of elimination
Cheers,
George

[Samurai]

I have an identical problem with my 1959 175TS. I have rebuilt the engine completely and replaced all the bearings. Like you I get an oil leak from the same spot and have tried all the 'normal' fixes.

I've remove front sprocket (it is already the one supplied by Nigel Lacey with the correct oil scroll) and use high temperature silicon on the back and the groves where it mates with the output shaft.

I torqued the nut up to about 80 Nm.

I replaced the clutch push rod seal (I had fitted the Nigel Lacey conversation kit so this was pretty straightforward).

I had fitted the optional oil extension tube and dipstick when I rebuilt the engine and had always filled to the too mark. I therefore also reduced the oil level till it was just showing on the bottom of the dipstick, which equates to 'brim full' if using the normal narrowcase oil filler plug.

All this has helped to a degree, but in my case I feel that the main problem is that the clutch pushrod arm pivot hole is worn. This is allowing the pushrod itself to move off centre slightly, wearing the seal lip and allow oil to pass, especially when changing gear. My own fault for not fighting more with the roll pin when the cases were apart, instead thinking 'Oh, that'll be ok it can't do any harm!'

Just worth a thought.

Cheers,

Jason.

[DuranMendoza]

Thanks everyone so far for the help, I do appreciate it.

It turns out that the oil is coming from behind the sprocket, as can be seen in the photos. I put the chain back on the bike shifting through the gears with the bike on the center stand.

1. My chain I have noticed is too loose, causing a lot of back and forth and wobbling. I plan to tighten this up.
2. While running the bike I noticed the rear sprocket has some play in it, that I will need to fix, and might require some parts.

The above being noted, I checked the front sprocket, and didn't notice any play or flexing. If I fix the chain tightness, does anyone think this will address the issue, or does the case need to come apart? Should I pull the front sprocket?

Thank you all again,
Duran

[Jordan]

As you have confirmed that it is leaking from behind the sprocket, how about removing it and having a closer look?