Points cover small leakage

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NorCat

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Feb 26, 2015
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The point cover on my Mk3 leaks some oil drops through the small drain hole.

I have replaced the seal and is not completely oil tight.

I have Pazon Altair electrònic ignition, and I'm thinking of closing the little drain hole, would that be a bad idea?

Thanks in advance for your opinions.
 
NorCat said:
The point cover on my Mk3 leaks some oil drops through the small drain hole.

I have replaced the seal and is not completely oil tight.

I have Pazon Altair electrònic ignition, and I'm thinking of closing the little drain hole, would that be a bad idea?

Thanks in advance for your opinions.
Click to expand...
The hole is performing as designed. That is a weep hole.
Do not block it.
 
NorCat said:
The point cover on my Mk3 leaks some oil drops through the small drain hole.

I have replaced the seal and is not completely oil tight.

I have Pazon Altair electrònic ignition, and I'm thinking of closing the little drain hole, would that be a bad idea?

Thanks in advance for your opinions.
Click to expand...
Did you use a tapered points seal tool when you put the timing cover on?
Or at least some some insulation tape?
 
NorCat said:
The point cover on my Mk3 leaks some oil drops through the small drain hole.

I have replaced the seal and is not completely oil tight.

I have Pazon Altair electrònic ignition, and I'm thinking of closing the little drain hole, would that be a bad idea?

Thanks in advance for your opinions.
Click to expand...
I can think of several reasons for the seal to leak.
1) Remove the Pazon rotor and inspect the end of the cam. The cam should protrude into the points cavity. It should be close to centered in the hole it's through. And, you should just barely see the seal against it.
2) That seal is one of the hardest to put in so it's easy to damage it, get it in crooked, or not get it in all the way.
3) The seal can be put in backwards. If backwards, it will not seal.
4) The end of the cam can have a burr or be worn so the seal does not fit snuggly all the way around.
5) Unless using the special tool or equivalent when installing the timing cover, the seal can be damaged.

That cavity should be bone dry. The drain hole is for any water that gets in to drain. There should be no oil in the cavity. If there's a tiny film of oil, the seal is leaking but that won't hurt anything - if there's actual oil coming out the drain, you have a big leak.
 
Many thanks for your replays, I will not close the hole and put a new seal as is probably slightly damaged or reversed, if so how do I know the position?
 
NorCat said:
Many thanks for your replays, I will not close the hole and put a new seal as is probably slightly damaged or reversed, if so how do I know the position?
Click to expand...
Points cover small leakage
 
After removing the seal , inspect the end of the cam itself where the seal contact area is to it . I've seen tiny pitting marks where water and rust marks formed . This was on a rescue machine found abandoned outdoors for a while .
Use the special tool to fit , it's cheap .
Spring side of the seal fits inwards , towards the engine .
 
kommando said:
The spring side always faces the high pressure. So spring side faces the engine.
Click to expand...
Yes I agree
But a mate of mine races a Ducati 750ss Which has basically the same oil seal setup that a commando or unit triumph has
One workshop manual showed it facing in
One facing out
He spoke to Ducati about this and they basically said don't worry about it'll work either way !!
He's very particular
So he tested it with the seal fitted both ways and tested with an oil pressure guage and found the readings identical
He can't work out why the results are the same?
We both had thought that the garter side of the seal would lift and lose at least some of the pressure!!
Footnote
This is the crankshaft seal ,so is under pressure
 
Last edited:
baz said:
Yes I agree
But a mate of mine races a Ducati 750ss Which has basically the same oil seal setup that a commando or unit triumph has
One workshop manual showed it facing in
One facing out
He spoke to Ducati about this and they basically said don't worry about it'll work either way !!
He's very particular
So he tested it with the seal fitted both ways and tested with an oil pressure guage and found the readings identical
He can't work out why the results are the same?
We both had thought that the garter side of the seal would lift and lose at least some of the pressure!!
Click to expand...
Because the seal is under little pressure, splash oil only. If a check valve type breather is fitted, mostly negative pressure.
That seal has an easy job.
 
concours said:
Because the seal is under little pressure, splash oil only. If a check valve type breather is fitted, mostly negative pressure.
That seal has an easy job.
Click to expand...
Sorry I meant to say it was the crankshaft oil feed seal so it's under a great deal of pressure
I'll amend my post
 
If you look at the shape of a garter seal in x section then you will see

1 is the spring and 3 is the seal edge.

Points cover small leakage


now you can see that pressure from the spring side presses the seal edge onto the shaft and from the other side will lift the seal edge and so decrease the pressure.

If your pressure you wish to seal against is 100psi and the spring side works to 150psi and the other side works to 120psi then in a test both ways result in no leaks and you will see 100psi on a gauge. If your pressure is 130psi then only the spring side will work and show 130psi, the other side will fail at 120 psi, slightly at first but then more at 130 psi and the gauge will show less than 130 psi pressure.

So what you see on a test depends on the relative pressures.
 
kommando said:
If you look at the shape of a garter seal in x section then you will see

1 is the spring and 3 is the seal edge.

Points cover small leakage


now you can see that pressure from the spring side presses the seal edge onto the shaft and from the other side will lift the seal edge and so decrease the pressure.

If your pressure you wish to seal against is 100psi and the spring side works to 150psi and the other side works to 120psi then in a test both ways result in no leaks and you will see 100psi on a gauge. If your pressure is 130psi then only the spring side will work and show 130psi, the other side will fail at 120 psi, slightly at first but then more at 130 psi and the gauge will show less than 130 psi pressure.

So what you see on a test depends on the relative pressures.
Click to expand...
I think he said it was running at 80psi ?
I can't remember now
I had thought a hot engine with hot oil would have lifted that garter and let some pressure go
But maybe 80 psi isn't enough
 
baz said:
I think he said it was running at 80psi ?
I can't remember now
I had thought a hot engine with hot oil would have lifted that garter and let some pressure go
But maybe 80 psi isn't enough
Click to expand...
maybe it was a cold engine… and he was running Castrol R… so long as the seal was within an 1/8” of the crank, no oil would get past !!
 
kommando said:
If you look at the shape of a garter seal in x section then you will see

1 is the spring and 3 is the seal edge.

Points cover small leakage


now you can see that pressure from the spring side presses the seal edge onto the shaft and from the other side will lift the seal edge and so decrease the pressure.

If your pressure you wish to seal against is 100psi and the spring side works to 150psi and the other side works to 120psi then in a test both ways result in no leaks and you will see 100psi on a gauge. If your pressure is 130psi then only the spring side will work and show 130psi, the other side will fail at 120 psi, slightly at first but then more at 130 psi and the gauge will show less than 130 psi pressure.

So what you see on a test depends on the relative pressures.
Click to expand...
Good explanation - better than any I've come up with. Also, I would want to see the same test after 10k miles, at 90psi, and hot oil. Then after 10K, 90psi, on cold start. Most things are overrated to provide some protection for the extremes. I can easily see where a race bike, blueprinted, and well maintained could provide the results @bas friend got but tests without conditions don't always tell the full/true story.

I absolutely will never install and Norton seal backwards, but I doubt that the cam seal makes a difference since, at least on a bike with a reed valve, there is little to no pressure. They definitely would be easier to install backwards! A "X" style seal like used in the gearbox might be just as good.

BTW, pressure is not the only reason for seal orientation. The earlier Triumph unit construction engines were to have the drive-side crankcase seal installed spring towards the primary. The thinking being to keep primary oil out of the crankcase. I installed them wrong for years thinking correct was to keep the engine oil out of the primary. Later, Triumph engines shared crankcase and primary oil and pressure so it clearly made no actual difference
 
Fast Eddie said:
maybe it was a cold engine… and he was running Castrol R… so long as the seal was within an 1/8” of the crank, no oil would get past !!
Click to expand...
No he doesn't use Castrol R
He races in the Ducati desmodue championship
It's a great series,it gets people racing for a few thousand quid
 
kommando said:
If you look at the shape of a garter seal in x section then you will see

1 is the spring and 3 is the seal edge.

Points cover small leakage


now you can see that pressure from the spring side presses the seal edge onto the shaft and from the other side will lift the seal edge and so decrease the pressure.

If your pressure you wish to seal against is 100psi and the spring side works to 150psi and the other side works to 120psi then in a test both ways result in no leaks and you will see 100psi on a gauge. If your pressure is 130psi then only the spring side will work and show 130psi, the other side will fail at 120 psi, slightly at first but then more at 130 psi and the gauge will show less than 130 psi pressure.

So what you see on a test depends on the relative pressures.
Click to expand...
i was always taught that lip type seals were not designed to take constant pressure or being loaded
 

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