OIL FILTER TUNNEL LEAKS...Some thoughts.

[Les Howard]

So many thanks ajscomboman. Your comprehensive reports on your attempts does encourage me. As regards the 2 thou paper gasket availability. As mentioned above. I have that modern grease proof paper (Sainsburys) looks perfect for the tunnel gasket. It is 2 thou thick and made of super tough heat resistant paper. QUESTION: It seems you had complete success with the full gasket? I ask as you seem to say you have resorted to a very thin paper gasket just at the tunnel simply because it is easier, I guess? I've never used Threebond but will buy some. As also said, if one was stripping the motor for a complete service then it's all part of the job but to remove and tear down the engine (for the 3rd time!) just for the leak not knowing or feeling completely confident that it might STILL leak gives me a feeling of utter dread and nightmares. RE: The AMC kickstart seal. It's a mystery why my G12 one leaks so much...I'm sure they don't all leak that badly. I did try the X Ring but although bought from RGM Motors it seemed too small and sure enough leaked even worse. I reckon I will need to do my own measuring and buy a larger size one to have any chance of sealing it.

[Les Howard]

Re: shaunstaples IDEA:.. Thanks for suggesting this idea. You've obviously given the problem some time thinking about it. I reckon there is just a little bit of space but maybe not enough to house the O rings inside the tube without first reaming both side of the tunnel out first to create the space. One could try the tube inside the tunnel as it is if the tube was a good sliding fit inside the tunnel. make the tube about 1" long and have the tunnel completely dry and clean. Apply the Loctite 518 to the area that the tube will slide over. It is anaerobic and will set in about 24 hours with a sealing potential of 1000 PSI!..One thinks immediately of how to strip the engine down in future, but I would use a gas torch to heat the area first and simply push the tube inwards, after the compound softens, to clear the centre joint and carry on the strip down in the normal way. I may well try this myself as an expedient measure soon.
REGARDING A TOOL TO CUT AN O RING GROOVE AROUND THE TUNNEL JOINT:
It would be relatively easy to make a tool to cut the groove simply as follows: On a lathe make a circular boss/spindle to fit into the tunnel of one side (engine stripped of course) The boss would have a lip on it at the same diameter (or a touch smaller) of the O ring. Then a cutter blade tip is welded on to the boss to cut the groove. The lip on the boss would correspond to the required diameter of the cut groove for the O Ring. This would also act as a depth-stop for the cutter/s of the groove. Ideally 2x cutters at 180 deg. could be attached to the boss but one will work and would be easier to accurately set the O ring diameter and its width....maybe one cutter could be a touch thinner and one the exact width of the required groove. This would ensure more accuracy. Then the boss/spindle cutter could be used in a hand-held drill to simply and safely cut the O ring groove. There will be no wobble or fear of getting it off centre or too deep and the routing of the hole would take just a minute or two. I'm sure this tool could be made very easily. Test the tool on an old sheet of aluminium with same diam hole in it. See attached basic idea for the tool:

O RING GROOVE CUTTER TOOL.jpg

[Les Howard]

Thanks Groily. The photos of the bike are fresh from the extensive restoration I gave it. It needs to be used but this year my health has been below par. The Prostate TURP surgery I had this summer (what summer?) took some time off my activity and I have some unexplained giddiness for ages that makes me reluctant to ride a motorcycle...Things should improve at some time I hope...All the best...Thanks again

[shaunstaples]

I haven't measured the chamber or filter and have changed my filter earlier this year but didn't take much notice how tight the filter was. If possible I would prefer to only ream the chamber to get a good surface for the seals? and try and move the pressure away from the joint by having the seals inward. As you say one side of the dowel could be glued / sealed into one half of the crankcase and then the o ring side slide out. Its a shame the filter couldn't be shortened and have the seal at the end like your original idea. Just doesn't look right having a gasket without a recess for it?

[Les Howard]

That's a good idea to ream the tunnel, Shaun if you wanted to try the INTERNAL thin tube and seal it with Loctite. At the moment I haven't done any measuring so unsure of the clearance. If you intended to bore out the tunnels after dismantling, to fit a larger diameter tube with the O ring seals as you show in your diagram, I would favour the much quicker and safer job of cutting a single O ring groove...see my suggested tool above. With sufficient squash on the O Ring, it must seal effectively I would think. Remember you don't have a lot of metal surrounding the tunnel. The simple paper gasket can work but in pure engineering terms it is a bodge, but an O ring should allow the cases to fully close.

[shaunstaples]

Yes just got to get the nip of the seal right. Would be nice to get the pressure away from the joint of the crankcase.
I'm ready to strip my engine but still way off this type of work yet and I'd have to get donor crankcases to work with, I'm a worrier too!

I can have a go at cutting greaseproof on the laser cutter, its weird what it will and wont cut.

[Groily]

in case it's useful, some dimensions, taken off a '54 500 engine. I think the basic dimensions remained the same throughout for the twins.

Pic shows minimum wall tunnel wall thickness of c. 4.8 - 5mm.
Tunnel diameter is 1 1/16th, and felt filters (best as I can measure squashy things!) are 15/16ths, both the earlier floating sort (with steel cup the T/S end and alloy plug & spring on the drive end) and the integral later type.

filter tunnel walls.jpg

[shaunstaples]

Not much at all then Bill, that's only 1/16 clearance for the filter, it would have to be a thinner filter to gain some room. Prob just enough to get a thin section seal like a dowty washer works using a recess to keep its shape. Just making a weaker point where pressure is?

[ajsph]

in the last 4 twin engines I have rebuild, I have made a groove in the drive side for an o ring with an inner diameter of 29mm and a thickness of 1mm, I have made the groove 0.9mm deep
Regards
Poul Denmark

[shaunstaples]

Managed to cut one 2nd attempt, set fire to 1st one! I found some old baking parchment which is 2 thou

edit: just read the label and it says this product has been treated with silicones, which repel sticky liquids so probably not much use

Recess and o ring is permanent job, do you have any pictures please poul?