OIL FILTER TUNNEL LEAKS...Some thoughts.

[shaunstaples]

The reverse side was harder to true up before machining whereas the grove side ( the one used for all the tests ) was within 1/2 thou flat against chuck. So thinking about it can probably disregard the chamber side result. ( rewind back to how I got the finish and it was faced to get flat then on linisher to get finish somewhere near and then lapped with coarse then fine, to get to a faces that I felt might work )
So all the test results are done with the same two faces, except the last test on reverse chamber side of the bottom plate.

[shaunstaples]

Since then I’ve set up with a thin smear of RTV on the original groove side and left overnight. I got holding 200 psi and >3500psi unable to make it fail. I will do another test with less nip with and without RTV.
I’ll probably do a few tests, incrementing from the greaseproof until it drops the holding pressure then finally apply RTV with that thickness of packing. This could emulate poor crankcase faces? Unless someone has a better thought?

[shaunstaples]

Hi Shaun...can't quite make out what you mean with this sentence: "bad news is chamber side won’t hold pressure and falls back to zero whereas groove side is holding just over 200psi."

Les, pic 1 of last pics is of new 32mm dia chamber on reverse side of endplate
The o ring fits inside this new chamber
Pic2 is of the original test side of the endplate with the o ring fitted in the groove and the reverse side of the top plate with the original 27mm dia chamber
Pic 3 is of the bottom plate, test side just after machining. This shows protrusion of o ring.

[Les Howard]

Hi Shaun...putting the O ring size of 30mm OD with 1mm thickness in the calculator we get the following. Don't worry about the Squeeze being a bit small with the standard size tolerances...Note how the inner diameter of the groove needs to be about 27.5mm OD with 0.9mm squeeze depth...REASON: O ring rubber does not really compress...the more you squeeze it flat, the wider it will spread...Try using the calc yourself and see how the measurements interrelate. The two rows of results at the bottom are caused by tolerances of the O ring and machining...min and max. PS: You don't want the O ring holding the flange apart or too tight and damage the O ring...it needs squeezing and settling flat without damage once tightened. PS as far as I can search a 30mm OD x 1mm thick VITON O RING IS NOT manufactured...Need a different size...if Viton chosen.

Screenshot 2023-10-13 151041.png

[ajscomboman]

30mm x 1mm Viton o rings are a standard size ring Search Polymax website

[shaunstaples]

Les, not really sure why the chamber side wouldn’t hold pressure, the nip on the o ring on both sides was 9 thou both sides of the end plate, The o ring groove we cut on the original has no side clearance but did nip up and hasn’t any damage to it after tests. I’ve entered the dimensions of the groove into the calculator and it’s outside the recommended parameters. I can get into the recommended parameters by providing extra internal clearance.
The o rings I’m using are 30mm ID x 1mm thick nitrile and are available in viton.
I’ll probably do the checks for less nip, before I add the internal clearance, in case it won’t hold pressure with the internal clearance.

[shaunstaples]

Thanks Rob I’ve just this minute found them, I bought the nitrile ones because they were cheaper just for testing.

[shaunstaples]

Looks like there's about 1.5mm to come out for internal clearance.
We did the groove square too, so I set the groove radius to the smallest positive value 0.001mm

Rec. o ring.JPG

[shaunstaples]

Les,
Finally got a bit of spare time to do some further testing packing the plates apart with shims of a broken ring around the o ring, greaseproof 0.0015", normal paper 0.003", and thin card 0.009". The o ring protrudes 2 1/2 thou from the groove so in theory with the card it shouldn't be any compression. The card after the test is about 0.008".
Not really sure why but may be the 0.0025" nip deforming it?
I was trying to simulate poorly mating crankcases and expecting it to fail not improve!
So next I would like to take the groove deeper and remove all the protrusion to see what happens, but also would like to provide the internal side clearance to see what happens. either one will need a re-face to get the other test done and the faces could be better or worse. ( Very lucky for me to get a seal before )

Results.JPG

Pic of card shims

[dave16mct]

Just about to do this. I've made a tool and tested it on a scrap (very) crankcase and it worked very well. The trouble I have is measuring the depth accurately. I went for 33 thou which I thin is 0.85mm. I can only do this using feeler guages under the depth stop of the tool. Seems good with the 29x1mm O ring. I've also bought some very expensive ThreeBond. Dave
PS many thanks for all your hard work and research on this subject!