How do O Rings stop oil leaks?

[Ian C]

. . . Not sure if this is relevant, but the take-off casting on the side of my block wasn't flat. I used an old mirror, lots of water and wet'n'dry to ensure it was perfectly flat. I also had to have a couple of goes at making different paper gaskets of different thicknesses and checking everything was torqued in the right order and to correct specification. Still leaked a bit, and then virtually stopped.

Kevin,

Thank you and yes it might be. It looks like the O-rings are extruding under pressure which may be caused by incorrect sizing or a larger than acceptable extrusion gap. This could well be caused by a deformation of either the adapter plate or the mounting face on the engine.

I was thinking of trying Plastigauge to see if I could measure the gap but not sure if this would work. I might start with engineers blue on the mating faces and see if there are any high spots.

More research on O-ring sizing has revealed that the selected O-ring was not far away but I have order other O-rings that are closer to the (theoretical!) ideal size and are also are harder (higher Sh number). The attached shows the calculations for Squeeze Compression, Installed Stretch & O-Ring Gland Fill nthat I used. Counter intuitively it looks like the smaller (in cross section terms) O-Ring will give a better seal - subject to the correct extrusion gap!

Take care,
Ian

[KevinW]

I tried using some Parker pen ink to check flatness and managed to convince myself it wasn't flat. So over to Youtube for tutorials on how to do lapping by hand- it was very easy.
I think you are going to be the go-to expert on O-rings after this - best of luck with it.

[Ian C]

So it looks like my new found O-ring knowledge will be wasted! The problem appears to be poor manufacturing of the adapter plate.

I cleaned up the surfaces of both the adapter plate & the engine mounting and then applied engineers blue to the adapter plate which was then mounted to the engine and the fixings tightened. The adapter plate was then removed and the second picture shows what greeted me. The glands for the O-rings and the hole for the oil flow & return are not concentric with the holes in the engine. In fact they are so far off that parts of the O-rings appear to be over the holes in the engine face. This would explain the strange distortion of the O-rings that I had put down to extrusion of the O-ring (see 3rd picture).

So now the question is where to find a better qaulity adapter plate for the 1UZ, any suggestions?

Take care
Ian

[aaronjb]

Yeah, that is, as the Germans would say .. nicht gut! I'm not sure how the Japanese would say it..

At least you found the source of your problem, hopefully one of the other 1UZ folks will have a source for a better adapter

[KevinW]

As Aaron said, glad you got to the bottom of it.
So not flatness, but poor geometry.
Just looking at the pics above....and I know its a total PITA, but if you have a drill press, you could buy a block of ali from ebay, chain drill the curves to the correct shape and drill the holes in the correct spot and tap the sensor holes yourself?
At a slightly simpler level I made a 10 mm extension piece for my header tank using this approach.

On my FE there are no O-rings in this position - the seal is purely provided by the compression of the gasket between the block and take-off plate, held by 4 corner bolts.

[TonyD]

Locktite MR 5922 Flange Sealant.

This is the go-to sealant that Lexus use to seal stuff in the factory instead of gaskets.

Definitely worth a go I would think.

Cheers,

Tony

[Ian C]

As Aaron said, glad you got to the bottom of it.
So not flatness, but poor geometry.
Just looking at the pics above....and I know its a total PITA, but if you have a drill press, you could buy a block of ali from ebay, chain drill the curves to the correct shape and drill the holes in the correct spot and tap the sensor holes yourself?
At a slightly simpler level I made a 10 mm extension piece for my header tank using this approach.

On my FE there are no O-rings in this position - the seal is purely provided by the compression of the gasket between the block and take-off plate, held by 4 corner bolts.

Kev,

Thanks but I think you are confusing my technical abilities and skill levels with those of others on this forum. I would love to have the wherewithal to do machining & cut threads etc but alas I know my limits. The simple approach is often the best and four corner bolts & a gasket sounds like the best approach unfortunately the 1UZ is not so equipped.

Take care,
Ian

[Ian C]

Locktite MR 5922 Flange Sealant.

This is the go-to sealant that Lexus use to seal stuff in the factory instead of gaskets.

Definitely worth a go I would think.

Cheers,

Tony

Tony,

Thanks for the suggestion but I think I am going to try an source a correctly machined adapter that will fit, and hopefully, seal properly.

I will update the other (newer) thread "1UZ Oil Leak - Remote Filter Adapter" with how I get on.

Take care,
Ian

[aaannnd]

Or make an extra adapter plate, add longer bolts and another 2 orings. Holes on top and bottom should be moved to fit engine and your adapter.

[Ian C]

Or make an extra adapter plate, add longer bolts and another 2 orings. Holes on top and bottom should be moved to fit engine and your adapter.

Hi Andrzej, hope you are keeping well.

Another good idea but the space is very tight (I already had to reshape the lower chassis rail to clear the oil hose unions) and my skill levels are not up to what you suggest. I did use the information you kindly sent for the machining of the adapter plate to join the output of the BMW gear box to the flange on the prop shaft so a belated thanks for that.

Take care,
Ian