OIL FILTER TUNNEL LEAKS...Some thoughts.

[shaunstaples]

1500psi.jpg

New Gauge.jpg

[shaunstaples]

Cutter.jpg

Something along those lines, more robust than the picture suggests

[Les Howard]

A fantastic experiment Shaun and wow. what an enormous pressure for the paper to hold..1500PSI!...Was that just dry?. I ask because I made a suggestion a few posts back that, if you had the paper gasket coated, say with Wellseal, on both sides it would be likely to pop at a lower pressure...this was based on theoretical logic....Another test for the gasket properties would be with say conventional writing paper as close to 2 thou thickness. Maybe the grease proof paper, being slightly slippery, might not be gripped by the surface as something more absorbent such as plain paper? By the way, when I said do the test without a gasket, I meant just apply Wellseal whatever, but no gasket at all....As regards the tool...Yes this looks to be ideal to do the job safely. The deep spigot will naturally self-centralise the cutter to be concentric to the tunnel (use plenty of oil on it). The shims or washers can be removed to obtain the desired groove depth for total safety rather than setting the vertical height on the drill, The right-hand side case should be easy enough to get flat relative to the drill/ mill stand...Excellent

[shaunstaples]

Yes it was dry, not 100% sure at the point it failed but did see needle peak around 1500. this one I've had at 200 overnight ok, I just built it up wet and will try and make it fail. I was thinking the accuracy of the faces was wrong but its probably closer to my 71 year old cases!
The greaseproof has the ability to hold the pressure, just how to install it, and if anything is better.
I will try Wellseal and also RTV as it bonds.
I will do the o ring groove on the lathe before starting to think about a cutter.
I'm doing the testing as I need to do my engine (low oil pressure) probably this winter, the gasket may help if someone doesn't want to machine the crankcases, but ultimately as Poul, Jean and Rob have demonstrated the O ring is the way to go - just how to get there.
Got hospital taxi run today so might not get much time.

[shaunstaples]

So the Welseal applied to the gasket took a little more around 1800 psi to burst it and held 200 psi ok.

I set up yesterday the RTV instant gasket by degreasing and applying a thin film to both halves, tightening until I could see a slight seepage then fully tightening after an hour. left overnight and tested this morning.

First I can't get it to fail ( pumping like crazy willing it to fail!! ) saw over 3500 psi and then yanking the grease gun off as quick as I can..

https://youtube.com/shorts/-FkBWLihPtM? ... 548BGYyXEg

after about 15 mins its lost about 100 psi but I think its the ball valve in the grease nipple as that seems to be wet after wiping it, I guessing that it will gradually drop to 200 psi like the rest have?

Les, Ive been looking for paper thin enough as really I would only like to go no more than 2 thou between cases?

Don't think there's any point of using a gasket with the RTV

I'm going to get some o rings 1mm section and ask my friend to assist with cutting the O ring groove to compare

[shaunstaples]

Thinking, I’ve coated the whole plate so the RTV might have an unfair advantage. I will repeat with a similar area to gaskets.

[Les Howard]

Well Shaun. It just goes to prove that you can theorize all you like but the proof is in the eating. Great experiments and surprising that the RTV stuff performed so well. As regards coating the whole plate, yes that would mean the width from the tunnel edges was vastly wider than the 20mm or so on the crankcase edges that surround the tunnel. It would mean the pressure is trying to push a massive amount of compound across the surface to escape at the edge. I guess just a ring of RTV would be more representative of the engine in reality. The paper ring is what would be used in practice so is a fair test. I tested a few paper samples and there is plenty of 3.5 thou, a very common gauge. I would be tempted to try that as well simply because it has a matt dry finish rather than the slippery greaseproof paper I initially suggested. Yes the O ring method is I reckon what we will both use but the experiments on the effectiveness of a 2 thou paper gasket is very well worth doing IMO. Let's face it, if the paper gasket is reliable why go to the effort to do the O ring of you don't have the capability to do it? Still worth doing a dry vs compounded paper gasket test I reckon. All very interesting Shaun...

[shaunstaples]

Les, tried 2 paper gaskets from 2 different paper sources (2 1/2 thou) and they are so flimsy I couldn't even apply Welseal without them tearing so gave up on that, the greaseproof is thinner and surprisingly so much stronger.
The other thing that's surprising is the RTV out performing the gasket with RTV. Must be similar but opposite what you said about having the Welseal each side of the gasket, providing a weaker path, but here the RTV is stronger with the gasket being the weakest link?

Results.JPG

Probably not that accurate as relying on the grease nipple to hold the pressure, it seemed to settle on 200PSI a lot and the higher pressure gauge not as accurate at lower pressure?

I'll get some o rings when I find them and ask for help with the groove and test with and without RTV too

[Les Howard]

Fantastic tabulated results Shaun. So very interesting, I think. Yes, the RTV coated greaseproof paper put on a good showing and, as you found out, coating it DID increase its performance contrary to what I theorised. I am surprised that the RTV produced the best seal all on its own, Somehow the flexibility but inherent strength of the silicon is acting like an O ring by squashing into the joint without letting loose its grip on the metal or shearing. A fantastic result...Now await the O ring that should seal the best by current engineering standards. Oh, just thought of another experiment that makes sense. I wonder how the best performing RTV on its own compares to the O ring when there is say 1/2 thou clearance. That is: tighten the compression bolts and turn back half a turn or whatever equals say the 1/2 thou (or even 1 thou) gap. This would make a very valid test for real like crankcases that might not be closing completely fully at the tunnel position...This is "only" 2x extra FINAL tests...So interesting Shaun!

[shaunstaples]

I could cut some sections of the greaseproof that will go outside of the O ring with a clear path for it to leak and then its got to be the O ring making the seal. The greaseproof is probably nearer to 1 thou when tightened up, maybe more control on how much "less nip" I get.

It may be a bit now as Ive got to get the O rings and then seek help to get the groove cut correctly.

Hope its been some help on having a better choice of which method of sealing it, certainly will help me to try and get it right.
Just doesn't seem right putting anything part way between two mating faces and expecting the rest to seal - unless you were to cover the whole crankcase face.