Norton Commando oil leaks

beast

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Apr 18, 2021
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Hi All

Have some last problems with a 69 Commando that is assembled from parts in a box sent from the US.
The problem is that the engine leaks oil all over the place when driving. The oil is on the exhaust, underneath the engine, on the oil pipes and on my boots and legs etc.
I think that the problem is related to the engine acting as a compressor and the oil comes from the front hole in the oil tank that under normal conditions will go to the air filter (but I use a smalle filter and it goes into the open air).
I also have extra oil in the primary chain housing that I need to drain now and then.
Please see pictures further down.

In hope for some good advices?

/Benny from DK
 
Last edited:
beast said:
Hi All

Have some last problems with a 69 Commando that is assembled from parts in a box sent from the US.
The problem is that the engine leaks oil all over the place when driving. The oil is on the exhaust, underneath the engine, on the oil pipes and on my boots and legs etc.
I think that the problem is related to the engine acting as a compressor and the oil comes from the front hole in the oil tank that under normal conditions will go to the air filter (but I use a smalle filter and it goes into the open air).
I also have extra oil in the primary chain housing that I need to drain now and then.
Please see pictures.

In hope for some good advices?

/Benny from DK
Click to expand...
Sounds like the bike has wet sumped IE the oil from the oil tank has drained into the sump
Then you have filled the oil tank up
Too much oil and no space for it to go
What commando is it? Any photos?
 
Extra oil in chaincase generally means the primary crank seal has gone or become dislodged
 
No
baz said:
Sounds like the bike has wet sumped IE the oil from the oil tank has drained into the sump
Then you have filled the oil tank up
Too much oil and no space for it to go
What commando is it? Any photos?
Click to expand...
No I keep the oil level just over the minimum right after I have stopped the engine.
I am unable to figure out how to add photos here?
 
beast said:
No

No I keep the oil level just over the minimum right after I have stopped the engine.
I am unable to figure out how to add photos here?
Click to expand...
Ok what model/year is your bike? Is the breather standard?
 
baz said:
Ok what model/year is your bike? Is the breather standard?
Click to expand...
It is a 69 Commando and the breather pipe goes from the front left top of the crank to the tank. I did not assemble the engine myself so I have no other details
 
Norton Commando oil leaks

Norton Commando oil leaks

Norton Commando oil leaks
 
Ok you should have a rotary timed breather on the end of the camshaft on the left hand side of the engine with a hose that returns to the oil tank and this is clear, not blocked ?
 
baz said:
Ok you should have a rotary timed breather on the end of the camshaft on the left hand side of the engine with a hose that returns to the oil tank and this is clear, not blocked ?
Click to expand...
I think that is correct. You can see the pipe in one of the pictures from the other side.
I do not think it is blocked as the oil comes from the hole in front of the oil tank. Think it is connected like this somehow.
 
beast said:
I think that is correct. You can see the pipe in one of the pictures from the other side.
I do not think it is blocked as the oil comes from the hole in front of the oil tank. Think it is connected like this somehow.
Click to expand...
Do you mean the braided hose on the top of the chaincase? It looks small in diameter?
So when you look in the oil tank you should see a small amount of oil returning from this pipe
Should also see oil from the return oil pipe
 
If the breather is working ok
You will have to wash the engine down and trace where the leaks are coming from
 
Which (central) oil tank is it as the one on the left in the first picture in the link below, with the breather spigot attached to the 'top hat' seemed prone to blowing oil into the air filter (when it is there). The one on the right is a later version with the spigot on the top of the tank.

S/central oil tank versions

These are the two versions of the "S" /central oil tanks I am in possession of. I will admit that I no longer remember the VIN of my original 70 canary yellow roadster. I also don't know which oil tank it had. Only anecdotally I heard at high speed it would suck out the oil of the cam end timed...
www.accessnorton.com www.accessnorton.com
 
baz said:
If the breather is working ok
You will have to wash the engine down and trace where the leaks are coming from
Click to expand...
Have done that with no clear indication beside the hole in the oil tank
 
L.A.B. said:
Which (central) oil tank is it as the one on the left in the first picture in the link below, with the breather spigot attached to the 'top hat' seemed prone to blowing oil into the air filter (when it is there). The one on the right is a later version with the spigot on the top of the tank.

S/central oil tank versions

These are the two versions of the "S" /central oil tanks I am in possession of. I will admit that I no longer remember the VIN of my original 70 canary yellow roadster. I also don't know which oil tank it had. Only anecdotally I heard at high speed it would suck out the oil of the cam end timed...
www.accessnorton.com www.accessnorton.com
Click to expand...
I will have to look when I return to Denmark as I am in the US right now
 
The first picture shows the gearchange spindle O-ring probably needs replacing (Item 40 or replace with an X-ring).
andover-norton.co.uk

Andover Norton Parts Drawings - Genuine Andover Norton Factory Parts - Commando Parts

Andover Norton Parts are the only Norton spare parts in the market manufactured to original drawings, within the factory-approved tolerances, from the correct materials, and with the correct finish.
andover-norton.co.uk
andover-norton.co.uk

Andover Norton - SEAL - GEARCHANGE SHAFT ( X RING TYPE) - 04.0006

SEAL - GEARCHANGE SHAFT ( X RING TYPE)
andover-norton.co.uk
Or, the case can be machined to take a proper oil seal (also the kickstart shaft).
 
Is that the speedo cable running from the left of the cylinder barrels back to just behind the clutch cable as that wouldn't be the usual route?
 
Check primary oil level by removing the primary case oil level bolt at lower left side; if more than a few ml's comes out with bike level then more than 150ml prescribed volume present. If it is accumulating while running, then it can only be from a blown/damaged crankseal or any of the three bolts holding inner primary case to engine case. I've had one of those bolts come adrift, despite new tabbed lock washers, leading to loads of excess oil and some getting out the felt seal of inner primary case.

A blown/damaged crank seal can easily occur from starting a bike after a wet sump oil situation.

Excess oil out the breather could be from wetsumping or from over filling oil b/c of a wet sump situation.
 
beast said:
What is the normal route?
Click to expand...

From the speedo (mounted on the left-hand side of the forks), it normally runs under the lower yoke/tree and is then cable tied to the RH down tube and horizontal frame tube section and continues on to the speedo drive gearbox.
 
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