Oil tank filter catastrophe - almost

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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REW
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Oil tank filter catastrophe - almost

Post by REW »

When I fitted the felt on chicken wire filter in my '53 M20 oil tank I took care to be sure the material did not foul the oil exit hole (a problem I had years ago with the same arrangement on my G3). 500 trouble free miles later I arrived at a lunch stop to find oil everywhere on the rear right quarter and pouring on the floor. Bugger.

Turns out that the rubber washer I made for the filter compartment cap had deformed under the pressure of an, er, enthusiastic ride. Bit of spanner work to put it back temporarily and home carefully to clean up and replace with a "proper" cork washer. Out for a test ride today, stopping every mile or so to check and find it still weeping a bit but pressed on with the bike running fine.

Next check and the oil tank is only half full! A few hundred yards later and it's down to the minimum. No oil being burnt (no smoke), no apparent leak bar the tank filter cap so gently keep going but another look and that's it, empty oil tank and spluttering return so stopped. It was a long push for home (if you know Bishop Auckland from near the rally site to my place.)

So, started to look around and took the oil tank filter out - can you see the problem?
DSC_0130.JPG
Drained the primary, replaced the tank cap only, put an inch or so of oil in the tank and started up. Ran a treat and oil returned strongly until the tank was full to the max line! So what is wrong with these blasted filters? I am not the first to suffer this sort of thing.

Sadly though the left hand head gasket is weeping some oil, presumably as a result of crank case pressure.

So, do I leave the filter out?

Or bend it well away from the oil hole?

Do I torque the head gasket and hope?

Or replace the gasket anyway.

How do others seal the filter cap?

All advice sought folks.
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Ron

1951 Matchless G3L thumping round the Durham Dales.
Mick D
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Re: Oil tank filter catastrophe - almost

Post by Mick D »

Hi

I'm not too sure what I'm looking at - are you saying the felt from the filter has blocked the return pipe? (the darker circle - and assuming the turn over is not too large)

If so, this also implies the by pass function has failed - the filter / cap should lift off of it's seating, (against the spring pressure), to allow oil to by pass it.

I suggest you ensure the filter can move freely within it's housing.

Bending the mesh a little further away from the oil return pipe can't do any harm either.

Regards Mick
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REW
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Re: Oil tank filter catastrophe - almost

Post by REW »

Yes Mick, the felt has bellied out into the oil hole - a small "hill" of felt sucked in, so the relief function couldn't work either. Flow at tick over looked ok but presumably at road speed was too low to return the oil so it built up in the crankcase (and primary).

And a (now) weeping head gasket? Nip it up maybe?
Ron

1951 Matchless G3L thumping round the Durham Dales.
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Rob Harknett
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Re: Oil tank filter catastrophe - almost

Post by Rob Harknett »

The felt does not look like the original dense felt. I have never ever replaced one of those filters. Just a good wash in petrol. If you still had the old cork & filter all would probably still be OK. My spare is an old filter picked up at a jumble and just washed in petrol. But I am unlikely to ever use it. The old ones in my bikes still OK.
G15 Roy
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Re: Oil tank filter catastrophe - almost

Post by G15 Roy »

There has been problems with this type of filler for years sometimes to long and sometimes to short not sure why it cannot be sorted. May be best to tell Gary so it can be sorted out.
Roy
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REW
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Re: Oil tank filter catastrophe - almost

Post by REW »

Yep, will do. What tool do you use to tighten head bolts? Presumably you can do so without removing the tank each time?
Ron

1951 Matchless G3L thumping round the Durham Dales.
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dave16mct
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Re: Oil tank filter catastrophe - almost

Post by dave16mct »

I torque the heads on my 1960 model 20 without removing the tank. I use a Britool 1/4 whit socket and I have a couple of short extension bars of different lengths. I have the long Tiger cub type head nuts, so it may be easier with those. The torque wrench can't be too big either. It's a bit fiddly but easier than removing the tank.
Dave.
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REW
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Re: Oil tank filter catastrophe - almost

Post by REW »

Thanks Dave. Club spares sell a Britool socket that looks thin walled so will try that.
Ron

1951 Matchless G3L thumping round the Durham Dales.
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ajscomboman
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Re: Oil tank filter catastrophe - almost

Post by ajscomboman »

REW wrote:Thanks Dave. Club spares sell a Britool socket that looks thin walled so will try that.
That plus a small 3 1/2" extension and 3/8" drive torque wrench is all that you need, or 1 Roy Bellett as an alternative. Meuller them down till they turn no more seems to be the motto! :rofl: :rofl:
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REW
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Re: Oil tank filter catastrophe - almost

Post by REW »

Got 'em. Mind you, it is only recently I have bothered with a torque wrench, "once more with feeling" works wonders :D

Because the repro filter stops short of the threaded neck I think it has been sucked sideways against the oil exit hole, felt then getting sucked in to almost block it. Seems to me if the filter where a bit longer that could not happen.

I know you wash and reuse your filter Rob (both of you!) but in the end, does the filter really do much?
Ron

1951 Matchless G3L thumping round the Durham Dales.
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