OIL FILTER TUNNEL LEAKS...Some thoughts.

[Groily]

Nice pix Poul. Very neat.
Boring head on miller with bespoke cutter is the best way to go for accuracy, secure set-up, and all those good things Les. Not that a mandrel with cutters mounted per your pic couldn't, but a boring head makes it a lot less stressful.
If you could persuade someone with similar kit to accept some beer vouchers . . .

[ChrisTheChippy]

Fantastic job poul ! Very interesting to hear about your other bikes without the seal fitted . I don't have access to those sort of machine tools but it might be possible to take the cases to an engineering firm and use your pictures to illustrate how its done .
Only other answer is the mandrel idea but probably not as accurate although a couple of thou either way probably wouldn't be to much of a problem. No one will ever get to see it .
Thinking about it that does rely on the tunnel hole being perfectly round .
Thanks for posting poul .

[shaunstaples]

For me Les it would have to be something that bonds well, with the high pressure on it.

Many thanks Poul for taking the time and sharing this with us. The pictures themselves tell the whole story.
This is definitely the best solution, and gets the crankcases together perfectly too.

Thanks again

[shaunstaples]

So from the pictures it looks like the filter chamber is a machined hole?
Could a bush/bearing be made to press into filter chamber that acts as a guide and support for a rotating mandrel holding a suitable cutter that can be adjusted in and out for depth of cut.
Two thrust washers could be made one 1.9mm and the other 1mm.
With the 1.9mm thrust washer between bush and mandrel set the cutter to surface height.
Then swap the thrust washer to the 1mm ( or varying thickness washers down to 1mm ) working down to 0.9mm groove.
With it being aluminium could it be done by hand?

[Les Howard]

Hi Shaun...As regards the paper O ring needing jointing compound on it. The factory stated that due to the very high pressure in the tunnel, jointing compound simply is not strong enough or in essence too fluid to retain the oil, as presumably, it gets pushed out. Using a trapped paper gasket works because it is not a viscous fluid and has an inherent strength when its entire surface is trapped under dry pressure by the crankcase faces. If you coat the gasket with jointing compound and create a sandwich of compound/paper/compound, you are actual back to the situation you had without the paper gasket fitted. In fact, it is twice as likely to leak simply because the compound once again can be driven off the gasket and, in this setup, there are now two sides it can leak out.
PS: Thanks for showing how it is done Poul...It still terrifies me though, as one minute handling/machining error can ruin the cases! I don't think I could find someone to trust to do it unless they were something like an F1 engine builder

[Les Howard]

Some more thoughts: Wouldn't it be nice to have a tabletop rig that comprised an alloy tunnel split in the centre and clamped together with 2x bolts/studs to replicate the engine filter chamber. It would simply have a connector at one end to enable high pressure oil injected into it. The objective, of course, is to see what method can create a perfect high-pressure seal with the simplest /cheapest method....Just a little pipe dream that went through my worried head

[shaunstaples]

So the greaseproof lives to fight another day! I was thinking bonding but dry, ok?

The chamber wouldn't be too hard to mock up, you could use a grease gun with oil.....

[Les Howard]

Hi Shaun...Well it's all theory of course and one would have to anchor the greaseproof paper rigidly enough for the assembly of the 2x cases. I reckon the original paper would have had some extra strong properties compared to writing paper. I spent hours some weeks back on the internet searching for 2 thou gasket paper but nothing at all. I can see you and myself plumping for the O ring though but as said before, I am meticulous on my rebuilds and if I had had the factory correct gasket on the FIRST rebuild, I am 99% convinced I would not have had the tunnel leak. Now it will be the 3rd time around is has to be a solid gold 100% CERTAINTY and guaranteed I will achieve success...As also said by me a couple of times...in the short term I will have a go at a sticking-plaster method...I would be happy enough with that for as long as it lasts I think....PS: The grease gun would work for testing on the rig but in my Pipedream, the test rig would have a gear oil pump driven by an electric motor and have a pressure gauged on the delivery pipe to it that you get up pressure in a few seconds....It's never going to be made though is it ...Cheers for your contributions Shaun.....PSS I'm intrigued to find out why Poul uses such a thin O Ring....maybe it's more effective than a thicker one...this "thin is better" is also relevant to gaskets too...

[ajsph]

I have used the thin O ring because there is very little meat left between the tunnel and groove
Poul

[ChrisTheChippy]

We all seemed to have missed the fact that poul stated he has never used the round seal . He has assembled engines which have remained leak free for years with just a smear of sealant . Definitely a cheaper and less stressful solution .Two facts definately established are that most seals are just too thick and that pouls methods work as they are tried and road tested . Major step forward I would say. I agree with les that one error and you've buggered the crank case up so it's a case of being really confident in your abilities.