Crankcase Oil Filter Missing?

Information relating to the Matchless G11 or AJS Model 30 600cc twin
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Crankcase Oil Filter Missing?

Postby DavidHulse » Fri May 22, 2020 7:41 pm

Apologies if this is a duplication. The similar post I just submitted seemed to disappear into the ether!
I'm trying to rebuild a 1958 G11CS, engine number 07976, which I bought as a box of bits twenty years ago. I've checked, and repaired as necessary, the many engine parts that were disassembled long before I got it (the last tax disc was 1972!). From reading the manuals, it appears the crankcase oil filter is missing, so I've purchased a new felt filter, filter seat, pressure valve and spring; but I can't fit them because the filter will not pass through a bronze bush in the filter tunnel, bridging the two crankcase halves. The bush is about one inch long, with a wall thickness of 3mm. It is a tight fit in the drive side and a slliding fit in the timing side. It appears to be proper, as it locates the filter tunnel gasket between the two crankcase halves.

The new filter element is a snug fit in the bush, but won't pass through it because there is an inward burr on the drive side outer end. The filter seat is a loose fit in bllind bottom of the timing side tunnel, with nothing to retain it. It would have to be installed in the timing side before joining the crankcase halves, as this won't pass through the bush either. My questions are:

Should I file off the burr on the inside of the bush so the filter will go through it, or would the snug fit restrict the oil flow?
Should the filter seat be attached in some way to prevent it falling over and blocking the tunnel when I withdraw the filter element for cleaning or replacement?
Should I assemble the engine without a filter, leaving out the filter seat, which would be rattling about loose in the tunnel?
Should I be looking for a dfifferent kind of filter?

Any advice or suggestions would be greatly appreciated. Thanks.

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Re: Crankcase Oil Filter Missing?

Postby clive » Fri May 22, 2020 8:41 pm

Cannot help with your queery but your posts are currently being moderated as you are not showing up as a member despite being one. You may need to ask the webmaster to sort it out. You wont have full access to the site currently.
clive
if it ain't broke don't fix

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Re: Crankcase Oil Filter Missing?

Postby DavidHulse » Fri May 22, 2020 9:13 pm

Thanks for your reply Clive, although I don't really understand it. I am a member, on page 349 of the members list, but I had to change my name very slightly in order to register for the forum. What else can I do?

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Re: Crankcase Oil Filter Missing?

Postby Eamonn » Fri May 22, 2020 9:36 pm

David Hulse wrote:Thanks for your reply Clive, although I don't really understand it. I am a member, on page 349 of the members list, but I had to change my name very slightly in order to register for the forum. What else can I do?



David, you have to use the same username on the Forum as you use in the Membership system in order that the Forum recognises you as a full member.
I'll send you a separate email with further details.

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Re: Crankcase Oil Filter Missing?

Postby DavidHulse » Fri May 22, 2020 10:15 pm

Thanks Eamonn. Login seems to be working ok now. All we need now is the answer to the technical stuff!

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Re: Crankcase Oil Filter Missing?

Postby Duncan » Fri May 22, 2020 11:18 pm

Hi David, there should not be a bush here it sounds like a previous owner has added one, you will need to ensure that you have good joint faces to ensure an oil tight fit. it is possible to fit an o-ring if the cases are machined around the filter tunnel or make a whole face gasket if you are worried about leakage from the tunnel, the paper gasket does work but defies logic.

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Re: Crankcase Oil Filter Missing?

Postby DavidHulse » Sat May 23, 2020 8:06 am

Thanks Duncan. I did wonder about that; but I would be worried that the small round gasket, without the bush or spigot, could become displaced, either on assembly or in service, and actually block an oilway. I had heard about machining a groove for an o-ring in another thread on this site but found it hard to believe such drastic action should be necessary. I'll take another, closer look at it. Thank you.

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Re: Crankcase Oil Filter Missing?

Postby dave16mct » Sat May 23, 2020 8:11 am

I wonder what was the purpose of the bush? I think as Duncan says check the area for the small paper gasket. I would then remove the bush and fit the filter parts you have bought. The alternative would be to rely on a remote filter in the return line (a good idea anyway). There is also the cannister type which screws on a fitment which replaces the filter non-return valve. This is on the feed side but is very visible on a twin with siamese pipes. The fitment is made by a club member. It'll be a cracking bike when you've done it! :D
Dave.

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Re: Crankcase Oil Filter Missing?

Postby clive » Sat May 23, 2020 8:19 am

Glad log-in is sorted. Given it some more thought as I have a 58 G11CS which similarly stood unused and in bits for many years until it reached me. The oiling system on the twins had an oil pressure relief valve fitted early on and again later but In between there was no relief valve fitted. In 1958 no relief valve was fitted. There are two types the earlier one falls out when the outer timing side cover is taken off. The later one fits internally on the inner casing. The valve you describe is a relief valve for the filter not the relief of pressure in the filter space as a whole. The oil pressure on start up with a cold engine can get very high before settling to operating level and consequently leak from the crankcase joint. My engine leaked badly around the crankcase seam around the filter housing. When replacing the paper gasket a colleague machined the inner casing to take the later relief valve which requires the later oil filter to be fitted. I suspect your PO fitted the bush as a way of trying to stop the leak.
I am not sure but my thinking is a tight fit around the outside of the filter is not good, but I have forgotten now how that filter and top hat fit and operate. I do remember that when I took mine out the top hat remained stuck in the housing and needed some assistance to come out.
Perhaps someone with more twin experience can take this further.
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Re: Crankcase Oil Filter Missing?

Postby REW » Sat May 23, 2020 8:51 am

I have just changed the felt filter in my '53 500 twin. I am not sure but it sounds like the bush being referred to on the inboard end of the filter housing is either fitted wrong way round or is a home made item perhaps?

On my machine that item is snug into the filter end and sliding fit down into the back of the filter tunnel.

I used a thick piece of wire with a hooked end to hoik the piece out when removing it - it needed a strong pull the first time I did the filter a few years ago to get it started 'cos the oil etc was a bit thick.
Ron

1951 Matchless G3L, (thumping round the Durham Dales) isolating in the garage 2m from the Ajay

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