oil filter

Information relating to the Matchless G12 or AJS Model 31 650cc twin
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GSAX1
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Re: oil filter

Post by GSAX1 »

rocketman wrote: ..... would guess the relief valve in the filter assembly is for bypassing the filter if the pressure required to pass oil through the filter is too high (clogged with filth). From looking at it I don't see how this would work since oil is forced through the filter from outside to in.........
The function of the valve in the filter assembly is to hinder oil from running down through the oil gallery towards the center and main bearings, when engine is stationary. Some people remove this valve, with wet sumping as a consequence.
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Re: oil filter

Post by Ib-Denmark »

GSAX1 wrote:
rocketman wrote: ..... would guess the relief valve in the filter assembly is for bypassing the filter if the pressure required to pass oil through the filter is too high (clogged with filth). From looking at it I don't see how this would work since oil is forced through the filter from outside to in.........
The function of the valve in the filter assembly is to hinder oil from running down through the oil gallery towards the center and main bearings, when engine is stationary. Some people remove this valve, with wet sumping as a consequence.

Oh thats why.
I have always wondered how it was working.
I would very much like to understand more of the twin lubricating system.
Is it a diagram somewhere? (One drawing tells more than a thousend Words 8-) )
Regards Ib
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1608
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Re: oil filter

Post by 1608 »

Not sure where this 'hindering' comes from! The sole purpose of the relief valve is as it says' a relief'. It is to relieve excess oil pressure, especially when the engine and oil are cold. Without the relief valve there is a danger of the oil pressure crushing the filter and also escaping from any weepy joints, ie crank case joint etc. The valve allows the oil to escape into the timing case and into the sump, lubricating timing gears as it does so. I experimented with a Viton ring under the sealing steel washer on the valve because I was a little concerned that even when the engine and oil were hot that oil was still by-passing the valve. With the Viton ring in place the valve ceased to work ( sealed too well)I could not stop oil from escaping elsewhere, especially from the freshly anealed copper sealing ring under the oil filter assembly nut, which by the way was done up very tight making no difference. Don't underestimate the oil pressure when cold.
Having re-read above post slight confusion with valves. The ball bearing and spring valve in the filter is to prevent oil draining back down from the rockers.
The valve at the end of the filter tunnel is a relief valve. Oil is not fed through this valve, the feed hole can be seen in the tunnel if you look carefully. The tunnel fills with oil and then passes through the filter, the flow is then split, part going to the big end and part going to the rockers via a small alloy drum called the oil distributer.
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Re: oil filter

Post by Ib-Denmark »

More relief info
In my search for a diagram i came across this useful info in Christians archives:
http://www.archives.jampot.dk/Technical ... b_1963.pdf
Maybe there is nothing new but it confirms what has been said here.
Regards Ib
Last edited by Ib-Denmark on Wed Oct 30, 2013 9:59 am, edited 1 time in total.
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Re: oil filter

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1608 wrote:......
Having re-read above post slight confusion with valves. The ball bearing and spring valve in the filter is to prevent oil draining back down from the rockers......,,
This is not correct. When engine is not running the oil from the rockers will flow down towards the center crank bearing. There is nothing that stops it from doing so. The purpose of the (ball) valve in the filter (NOT the one in the filter tunnel) is to hinder the oil in the oiltank going the same way.
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Re: oil filter

Post by Ib-Denmark »

GSAX1 wrote:
1608 wrote:......
Having re-read above post slight confusion with valves. The ball bearing and spring valve in the filter is to prevent oil draining back down from the rockers......,,
This is not correct. When engine is not running the oil from the rockers will flow down towards the center crank bearing. There is nothing that stops it from doing so. The purpose of the (ball) valve in the filter (NOT the one in the filter tunnel) is to hinder the oil in the oiltank going the same way.
Now i REALLY need that diagram! :o
Ib
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Re: oil filter

Post by 1608 »

What I meant was that the oil galleries leading to the rockers is supposed not to drain back, so when engine restarted the galleries are already partially charged with oil. I know that the oil already in the rocker area will drain down push-rods etc.
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Re: oil filter

Post by GSAX1 »

1608 wrote:What I meant was that the oil galleries leading to the rockers is supposed not to drain back, so when engine restarted the galleries are already partially charged with oil. I know that the oil already in the rocker area will drain down push-rods etc.
The ball valve in the filter will not be able to stop the oil in the galleries to drain down to the sump, since it is located before the oil distributor.
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Re: oil filter

Post by Ib-Denmark »

GSAX1 wrote:
1608 wrote:......

The purpose of the (ball) valve in the filter (NOT the one in the filter tunnel) is to hinder the oil in the oiltank going the same way.
Very interesting!
If i understand this correct it does not matter if the pump is worn or not. When it comes to wet sumping. If just the releif valve and this ball valve close tight? ;)
Is that right? Ib
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Re: oil filter

Post by ajsph »

If the pump is worn, the oil drip from axle ends, and the oil will seep from timing side into the sump.
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