OIL FILTER TUNNEL LEAKS...Some thoughts.

[robcurrie]

Here is a clip from a post I made quite a while ago:

<<<"Sorry for the delay in replying to this. I first had to find the spare o-ring I used, it measures ID 30 x 1.5 dia . The correct groove size for this will be ID 29.6 OD 33.4 depth 1.2 (giving you a 0.3 squash).

I borrowed a tool that was about 30 years old and quite blunt. I found a holesaw in a cheap set that I cut off and used to replace the original blade. The holesaw was a good interference fit on the spigot of the tool and I ground the outside of the saw to the correct diameter. The tool has a spigot which centres in the gallery hole and a step which stops the cutter at the correct depth. It can be used in a drill press.">>>

Actually, I used this tool in a hand drill - no problem. This tool is as described by Les Howard except that it uses the saw blade instead of the 2 cutting inserts in his design. I did this mod 11 years ago, and the joint is still completely oil tight.

Rob C

[shaunstaples]

Must be the only time shrinkflation works in favour!
Just bought some fresh paper, and it’s half a thou thinner

[shaunstaples]

Thanks for the reply Chris, very encouraging. I am just trying to mock up a simple chamber, to do a few tests ( just 2 discs bolted together ) and then moving on will machine an o ring groove on the rear of the cover plate to compare the two.
I’ve done something similar in the past with a hole saw, only in Perspex to house bearings, but surprising how accurate it was
Rob - Its an age thing sorry, used to fly model aircraft with a Chris Currie

[JEAN-NOEL]

Hello Gents,
When I was 17, in 1965, I had the pleasure of owning, thanks to several years of work during the holidays, and the generosity of my grandmother a wonderful 1957 M30. But it was leaking oil as a basket!
And especially at the the cylinders base, and around he oil filter tunnel.
On my G12CSR T&L machined in a half crankcase the housing to place an o ring.
Today, I am sad because I broke the mug Derrick gave me when I visited Elstow, which I used for breakfast for years.
But the crankcase has not lost a drop of oil since this improvement was made!.
Kind regards;

[shaunstaples]

Mocked up les’s pipe dream (sorry can’t run to a motor and pump), and 1 1/2 thou greaseproof holding well at just over 120 psi.
I lapped the two halves together then sandwiched the greaseproof between using 6mm bolts.
Initially the needle shot round to stop, thought I’d broke it and the ball on the grease nipple was leaking but now settled and holding pressure well.
One of the plates has a 1/8” deep recess 27mm diameter to provide a small reservoir
Could do with a higher pressure gauge to see what it will take to make it fail
Edit: it’s sae40 oil I’m using

[Les Howard]

WOW!!!.You are brilliant Shaun. I find it hard to believe you would actually build the test rig thing I described... I am bowled over. Really I am!...Perhaps try without a gasket too and then with no gasket and with Wellseal and see what results you get. The factory, when they said it needs a paper gasket, were in fact talking pressures of 800PSI presumably the early Twins did not have an oil pressure relief valve. We know however, that a far lower oil pressure is likely to escape in practice. The pressure relief valves are usually set not higher than 80 psi so 120PSI is well over. I guess if something is going to leak in this set up compressed air/gas would be more likely as would petrol or paraffin even. The leaks for a gas might show up better as the rig could be submersed in water to see if any bubbles emerge. The petroleum liquids are molecularly thinner than oil so should also be a more profound test. Such an interesting experiment I think...brilliant.

[Les Howard]

So many thanks ROBCURRIE...The sizes of O ring are really useful as is the sqeeze measurement. I'm also pleased you managed to do it with a similar mandrill type tool to what I described. This makes it far easier for the many who can't access a precision engineer but can get something made up (maybe even passed around to others?). I am extremely grateful to everyone who has/is contributing on this thread. Shaun is really going to town with things, and it makes it a fascinating read hopefully for many other members too...Cheers again

[Les Howard]

Some more thoughts regarding O ring sizes. For INTERNAL pressure seals the groove OUTER diameter is the same for the chosen O ring...this is because the O ring is pushed outward by the internal pressure. O ring rubber does not compress but the O ring needs to be squeezed to seal so there must be sufficient groove space for the O ring to deform into. I would conclude the groove can be slightly bigger than the nominal cross-sectional width of the O ring as long as the OD of the Groove is the same as the OD of the O ring:...Terms are explained in the blue question mark spots: SELECT "AXIAL FACE" on the header FIRST
https://ceetak.com/o-ring-calculator?fb ... 3d0w1nZ-gM

[shaunstaples]

So far the gasket seems to be happy at 120 psi and is intact,
but then ( they don’t like it up em! )
Got up to approximately 1500 psi and gasket popped, difficult to watch gauge and swing on grease gun.

Les, not sure the faces are good enough for no gasket, it’s hard to get them totally flat on linisher as it’s hard to hold. I’ve faced them in the lathe but I’m no engineer! I’ve finished them by rubbing together with fine grinding paste.
I will try and get help to get them better and get an o ring groove cut on the back to compare.
The gasket thinned very slightly too?

Going back to the cutter, if the filter chamber is a machined hole then a bush could be made to push in and cut an accurate circle and the thrust washers accurate depth. All done without a mill?
And maybe longer term loaned out by club?

[shaunstaples]

Tried no gasket and can reach 1000 psi but falls back to zero ( probably accuracy of faces)
I’ve put another gasket on with oil on faces and it’s sat at 200 psi.
Might try degreasing and light smear of RTV