ET: Engine (Twin) Oil Leak

nigsey

Well Known and Active Forum User
VOC Member
I appear to have an oil leak in the crankcase of my C twin which I think may have been caused by the main drive chain rubbing on the casing probably due to a slack chain. If that if the case I’m gutted because I’ve only had the bike a short while. Anyone else had experience of this and the problems associated with repairing it please?
 

Attachments

  • BF4DC38F-FDF8-4F8E-A17E-13905B8EBB02.jpeg
    BF4DC38F-FDF8-4F8E-A17E-13905B8EBB02.jpeg
    381.9 KB · Views: 57

Bill Thomas

Well Known and Active Forum User
VOC Member
Check to make sure the leak is from there,
I don't think it is, It's common to have those marks, Maybe not so bad as yours,
I mean there is a stud under that point.
As had been said before , It's easy to put too much oil in the gearbox,
The dipstick often reads wrong,
The best thing to do is drain the gearbox and fill with the right amount,
And see where it comes on the dipstick, Often it's at the very end tip , Not half way up the flat ?.
 

Peter Holmes

Well Known and Active Forum User
VOC Member
Hmmm, Clearly the chain has been run slack over a period of time, it is not that uncommon to see that sort of carving away metal by a loose chain, but I very much doubt that is where your oil leak is emanating from, more likely the sprocket oil seal has seen better days or an overfilled gearbox.
 

nigsey

Well Known and Active Forum User
VOC Member
Check to make sure the leak is from there,
I don't think it is, It's common to have those marks, Maybe not so bad as yours,
I mean there is a stud under that point.
As had been said before , It's easy to put too much oil in the gearbox,
The dipstick often reads wrong,
The best thing to do is drain the gearbox and fill with the right amount,
And see where it comes on the dipstick, Often it's at the very end tip , Not half way up the flat ?.
Thanks Bill, yes the oil does appear to be a little way up the dipstick, I’ll drain the gearbox as suggested and refill paying attention not to overfill. I haven’t interfered with the gearbox since I bought it, neither changed the oil or added to it, but then I appreciate the buck stops with me!
 

nigsey

Well Known and Active Forum User
VOC Member
Hmmm, Clearly the chain has been run slack over a period of time, it is not that uncommon to see that sort of carving away metal by a loose chain, but I very much doubt that is where your oil leak is emanating from, more likely the sprocket oil seal has seen better days or an overfilled gearbox.
 

nigsey

Well Known and Active Forum User
VOC Member
Thanks Peter, I’ll just hope it’s the lesser of the two potential problems, I’ll let you know.
 

Bill Thomas

Well Known and Active Forum User
VOC Member
Nigel, Just a thought, If oil was coming from there,
I think the stud comes all the way through from the other side ?,
Inside the Primary chain case, When we put the studs through we put sealer under the nut
which is bashed into a hollow recess, Oil could run along that stud ?,
Don't think it's that, But keep an eye on the primary level also.
Cheers Bill.
 

nigsey

Well Known and Active Forum User
VOC Member
Nigel, Just a thought, If oil was coming from there,
I think the stud comes all the way through from the other side ?,
Inside the Primary chain case, When we put the studs through we put sealer under the nut
which is bashed into a hollow recess, Oil could run along that stud ?,
Don't think it's that, But keep an eye on the primary level also.
Cheers Bill.
Bill, you just might be onto something there. I topped up the primary oil recently because it was very low when I checked it, bit of a coincidence maybe? incidentally, I made sure the oil didn’t go above the level plug.
 

Bill Thomas

Well Known and Active Forum User
VOC Member
Not sure if it's one of the studs I am thinking about, But just to show you the recess in the primary side,
There is a nut brazed onto the end of the long studs,
This is a photo from Robert USA,
I would try and seal it from the outside if you are sure where it is coming from,
But Vincents are known for oil leaks coming from far away from what we think !!.
 

Attachments

  • 20171117_152141_HDR.jpg
    20171117_152141_HDR.jpg
    243.8 KB · Views: 37

Robert Watson

Well Known and Active Forum User
VOC Member
At the risk of starting an international incident That would be me.

Robert - from the west coast of Canada ---- Canada. To be fair I only live 8 miles north of the 49th Parallel but the border has been closed for several months so it doesn't even count as close!

Loke others I would say an overfilled gearbox and oil getting past the seal or in between the main and output shafts.
 
Top