Filter error and c/case breather blow?

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
Dallis54
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Filter error and c/case breather blow?

Post by Dallis54 »

Dear Gentlemen, heres a combo of problems (maybe) and need to get advise(s). The 18S(C)-54 was running a few miles last fall with new oil and filter (unlegal when its been out from the register to long). Worked o.k enough and I drained befor winter. Now spring and new oil w filter, gearbox fix etc.
But life things happend and it was standing unstarted 2 -3 months. When starting (with some efforts) it had wet sumped a bit (no drama in oil tank) so as with an B33 I did just rev it a while until less smoke.... just when exhaust smoke dispersed the tang clamp on oil return hose start to leak. Here I did no attention on filter... Did fix that with screwed clamp ring, restarted. Fine - put the helmet on and then splash on the ground - assuming from breather connection to the (hard to see) the pipefrom the valv is is curvy (looks unbroken) but connection to hose looks old as well the hose goes all they way up to the vent pipe in oil tank. When I prev touching the pipe end running the engine with the oil cap removed, its more farting than I did expect. Sorry my (long) wording but I´m from Sweden... Now I intend to take off the prim chain cage etc. Can all be about a filter (mounting ) error as well when prev owner didnt use it...in 40 years the breather hose to tank is throttling... Vent hole in tank cup exist... however it did run a few miles last fall... If anybody gives a hint, it would be great / cheers Dallis 54
SPRIDDLER
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Re: Filter error and c/case breather blow?

Post by SPRIDDLER »

Dallis54 wrote: Wed Jul 13, 2022 8:36 pm The 18S(C)-54 was running a few miles last fall with new oil and filter.......Worked o.k enough..... Now spring and new oil filter,
I'm a little unsure which oil pipe is leaking but as you have fitted a new oil filter the first thing I would check is that it is good quality.
There are some badly made filters in the market as shown in the photos below.
The badly made filters will restrict the oil return, increasing the pressure in the pipes and perhaps causing the leak.
I suggest that you try running without a filter to test whether or not it is the filter that is causing the problem.
(If you have a good quality filter it isn't necessary to fit a new filter every time but just soak and agitate it in petrol to clean it).
Filter oil faulty.jpg

This is the suitable filter available from the club spares department.

Filter oil Correct.jpg
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Dallis54
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Location: Lidingoe SWEDEN
Location: Stockholm area

Re: Filter error and c/case breather blow?

Post by Dallis54 »

Many thanks - that can explain why the return hose tried to slide off the return to tank pipe. I remember the ends of the filter looked a bit fatter than the previous. So I´ll check without filter. Then when that return to tank was fixed and ready to go... it suddenly splashed out oil underneath more at the left side. Could later see some oil remain on hose but not much on the breather stud to case. See pict. Could it be so that the jerry filter increased overall pressure in c/case and residual oil in the vent hose caused that hoseconnection to open up too.. If the hose slipped also there - its easy done and check with the filter removed. You se the clamp is almost at bottom tight. Hope so then its easy to fix - BUT shall I fear that I need to replace diaphragm and breather.. ?
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dave16mct
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Re: Filter error and c/case breather blow?

Post by dave16mct »

Connecting the vent hose up to the vent on the oiltank won't help. Both should be open. Direct the crankcase breather pipe down towards the floor. you can direct the oiltank breather towards the rear chain sprocket.
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Taid
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Re: Filter error and c/case breather blow?

Post by Taid »

I'm confused .. nothing new ..

I understood the oil filter was in the feed to the pump from the tank, ...

Is this not the case ?

Is there a diagram of the oil tank internals anywhere?
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Now sold ... 1956 AJS 16MS Bitsa .. HSU 414 .. rebuilt/re-registered 1987
SPRIDDLER
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Re: Filter error and c/case breather blow?

Post by SPRIDDLER »

Dallis54 wrote: Thu Jul 14, 2022 10:44 am Could it be so that the jerry filter increased overall pressure in c/case and residual oil in the vent hose caused that hose connection to open up too.
Possibly. It depends whether the jerry filter is restricting the oil tank vent but it would create excessive pressure in the c/case.
On my touring singles the c/case breather has vented downwards via short piece of open-ended pipe (only about 7c.m. long) into fresh air behind the chaincase and not via a return pipe to the oil tank vent.
BUT shall I fear that I need to replace diaphragm and breather.. ?
It is highly unlikely that you will need to replace the diaphragm and breather. It is a very simple device; just a steel disc and housing. I cannot imagine how it would be damaged by high oil pressure.
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Dallis54
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Location: Lidingoe SWEDEN
Location: Stockholm area

Re: Filter error and c/case breather blow?

Post by Dallis54 »

Ahaa ! The hose from release valve / breather (in prev pict) was pulled so by the Prev Owner and I didnt questionized.
Great advise - Many thanks all !
SPRIDDLER
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Re: Filter error and c/case breather blow?

Post by SPRIDDLER »

Taid wrote: Thu Jul 14, 2022 11:01 am I'm confused .. nothing new ..

I understood the oil filter was in the feed to the pump from the tank, ...

Is this not the case ?

Is there a diagram of the oil tank internals anywhere?
The feed filter is just a short steel mesh in the outlet pipe.
Diagram below from.........the workshop manual ;)
Oil tank cutaway.JPG
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Taid
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Re: Filter error and c/case breather blow?

Post by Taid »

Thank you S..

Didn't realise it was more than just a tank size change after 55 ..

Had a 55 16ms new, but didn't recall the 'nut' on the tank top ..

So, forgive my ignorance, later models don't have a filter other than the mesh in the output pipe ..

I do recall that it was a lot easier to see the return oil flow back then, than it is on my current bikes .. .. the diagram explains that ..

Thanks again

T
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Now sold ... 1956 AJS 16MS Bitsa .. HSU 414 .. rebuilt/re-registered 1987
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Re: Filter error and c/case breather blow?

Post by SPRIDDLER »

No felt filter in the tank. Just the feed pipe.

It's all in the Spares List here:

http://archives.jampot.dk/book/Spares_l ... _G80CS.pdf
Oil tank - post '55.JPG
Oil tank parts post 55.JPG
Oil tank post 55 filter.JPG
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