ET: Engine (Twin) Persistent oil leak

998cc

Active Forum User
VOC Member
Russ, is the bottom side of the oil tank wet with oil?
I ask that because I chased what I thought was a multitude of engine leaks only to find that the problem was one big leak up top.
The eyes see oil on a fin and the brain says it must be coming from around here somewhere.
Not necessarily!


Glen
Glen.
I degreased the engine this morning in prep for a leak test. The petrol (fuel) tank is still installed; however, the bottom of the UFM is dry, as is the portion of the filler tube at the top of the tank. I will specifically watch for that problem during observation.
Regards,
Russ
 

Bill Thomas

Well Known and Active Forum User
VOC Member
We tried to fit a new Rocker feed pipe, Some years ago,
And found it was too thick at the top, So it could not NIP the washer,
We had to drill it out from inside to make it thinner.
 

998cc

Active Forum User
VOC Member
All.
For better or for worse, the baby powder trick was employed. It does show the origins of a few leaks. The major leak does appear to be from the rocker supply line. The short rubber line between the heads has a slow drip that falls right onto the front muff fins.

Also....The powder did indicate something more serious--a compression leak at the front head joint that only shows when cracking the throttle!! Never would have found that without the baby powder. Thank you Robert Watson!! :) So the top end comes off again.

Regards to all,
Russ
 

Robert Watson

Well Known and Active Forum User
VOC Member
And make sure the clearance to clamp and seal the liner with the head is correct.
20191105_133226.jpg
20191106_093354.jpg
 

greg brillus

Well Known and Active Forum User
VOC Member
I use a simple glass surface plate to do the same, only if it needs a small amount removed. Any more and we have a special gimbal type of jig that mounts in the mill and we can repair most anything on a Vincent head with that. I only lap the liner face to the head recess afterward and check with bearing blue..........Never had a head to liner leak so far touch wood. This preparation is most important if you want no leaks from this joint.
 
Top