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ET: Engine (Twin) Persistent oil leak

998cc

Website 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 Website 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

Website 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
 

greg brillus

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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.
 

Robert Watson

Well Known and Active Website User
VOC Member
Liners on this pair were pretty consistent at .125 + or- less than 1/2 thou. Recess was made .123
 

A_HRD

Well Known and Active Website User
VOC Member
All good stuff, but Russ, if you have newly painted Shadow heads, check that they are still torqued-down to 32 ft-lbs before removing them. A friend had the same compression-leak problem after a few miles of use and when he came to remove the cylinder-head-brackets the head-nuts below were loose! The thick new paint had "given-way"!

Peter B
Bristol, UK.
 

greg brillus

Well Known and Active Website User
VOC Member
Yes I can confirm that point, I just recently stripped a Shadow engine that had been running ok, but the cylinder head nuts were literally finger tight. That is why I always re-torque the heads after the engine has been hot and carry out the next day when it is cold.
 

bmetcalf

Well Known and Active Website User
VOC Member
Do you loosen the nuts on top of the bracket and then use a crow's foot wrench on the head nuts or strip the bike down more than that?
 

A_HRD

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VOC Member
Exactly as you stated Bruce, no need to strip the bike any further.
Peter B
Bristol, UK.
 

greg brillus

Well Known and Active Website User
VOC Member
Not even that far, I back off the cylinder head bracket nuts. Then back off each one at a time and pull down in one go using a 13/16" ring and open end spanner. I use to use a spring scale, and given the spanner is around 9 to 10 inches long I pull down to 40 pounds on the scale. I don't even use the spring scale anymore, as i have a good feel for when it is tight........Using just one stock paper gasket under the barrels the nuts usually pull down less than one clock deviation, that is from 12:00 to 1;00 I tend to mark the nut and the head with a texter pen so I can see how much it moved. It is rare that they don't move.......Generally if stainless nuts on studs are used the nuts can grab a bit, so I use anti-seize or even grease on the threads before the nuts go on.
 

bmetcalf

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VOC Member
I've seen a chart on dry vs. lubed torques. I wonder about the practical effect on the low torque we need to use. But, you don't want galling.
 

litnman

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VOC Member
Robert, what is the swing on that lathe! Huge. What is the sledge hammer for??
 

Robert Watson

Well Known and Active Website User
VOC Member
The lathe swing is 18in dia in the gap which is partly home made, about 16in without, and a 48" bed. It was built about 1939 and spent its working life in a motor rewind shop starting at a Westinghouse facility near to a new mill in Nanaimo that was one for the first to not use line shafts but all individual motors drives on the equipment. I was wondering who would be the first to ask about the sledge hammer!
 

998cc

Website User
VOC Member
All good stuff, but Russ, if you have newly painted Shadow heads, check that they are still torqued-down to 32 ft-lbs before removing them. A friend had the same compression-leak problem after a few miles of use and when he came to remove the cylinder-head-brackets the head-nuts below were loose! The thick new paint had "given-way"!

Peter B
Bristol, UK.
Good point Peter. I'll check them before pulling them.

Otherwise, the muffs and liners are new in this build. They seemed to lap in well, so the leak is perplexing. :confused:

Regards,
Russ
Northern California
 

vibrac

Well Known and Active Website User
VOC Member
I always go to about 28- 30 ft lbs and leave it overnight then goto 32 next day always clean paint from the under washer area and use the ended spring balance check after a first shake down with loosened bracket
This cylinder nut subject is the only time I use a torque wrench on a vincent
 

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