Boxerworks.com

Yes shim is potentially in the wrong order however if you have the later canister with the end swaged over it doesn't actually matter as then the shim isn't needed to protect the O ring.

If you don't have an accurate means of depth measurement then do this simple test.

Leave the filter out so that it doesn't interfere, then offer up the cover with the gasket, O ring and shim. You will feel straight away with hand pressure if there is some resistance before the cover fits flush. If there is no resistance then there is no compression of the O ring taking place. If there is a gap, which there should be, then the size of that gap is how much the O ring will get compressed. You could measure it with a feeler gauge and it's arguably a better method than depth measurements and calculations. This check by feel takes all of 30 seconds and will tell you straight away if the O ring was getting compressed or not.

Good morning, thank you for your continued input.

Please see the attached image of the cannister appears to suggest two things. No shim is currently installed and the canister is not the sharp edged version.

I have also taken images of the O ring which appears to be as new. I could potentially replace this however (and the filter) as I have a replacement in my possession.

@barry
In reference to your advice of feeling for 'some resistance before the cover fits flush' in your previous post. To my feel, when I hold the cover in place there is no resistance ... in fact it appears to me that the cover fits flush with the engine casing immediately.

Could it be that what looks like pitting on the engine case is causing the leak?

A 1990 engine shouldn't have a shim fitted! The end of the filter can is swaged over.It also should not have a gasket. The only sealing item in these late engines is the 'O' ring. Always source an OEM 'O' ring or one that is GUARANTEEED to have the same characteristics (some vendors supply ordinary nitrile rings which are not really suitable). OEM rings are white and are a lot softer than stock black nitrile rings.

Rob

ME 109 wrote: ↑Wed Jun 19, 2024 5:48 am Could it be that what looks like pitting on the engine case is causing the leak?

A useful observation, thank you. I just checked and the black appears to be residue left by the gasket. I shall remove it all before I put the cover back on.

Rob Frankham wrote: ↑Wed Jun 19, 2024 6:03 am A 1990 engine shouldn't have a shim fitted! The end of the filter can is swaged over.It also should not have a gasket. The only sealing item in these late engines is the 'O' ring. Always source an OEM 'O' ring or one that is GUARANTEEED to have the same characteristics (some vendors supply ordinary nitrile rings which are not really suitable). OEM rings are white and are a lot softer than stock black nitrile rings.

Rob

Thank you for your comment. My bike appears to not have a shim fitted. I am in receipt of a MAHLE OX 36 D filter which comes with the white O ring that you mentioned.

It appears to me that my bike was fitted with a gasket because a black O ring was fitted at the same time.

Nice eyes seeing the thin metal shim in the wrong place. The outer edge of the canister was remade at some point and rather than being a straight cut edge, the edge was rolled. Technically it might not need the metal shim, but that rubber washer is important for sealing. The shim may also be needed to create the proper squish on the o-ring.

If the o-ring looks perfectly round, then it's pointing to the fact that the setup in your bike is not correct. Without proper pressure on that o-ring, oil can bypass the filter and go straight to the sump or at its worst, reduce the oil pressure inside the engine.

This is what the parts look like coming out of my /7. Note I'm using a gasket in order to adjust the squish on the o-ring.

Kurt

Kurt in S.A. wrote: ↑Wed Jun 19, 2024 6:39 am Nice eyes seeing the thin metal shim in the wrong place. The outer edge of the canister was remade at some point and rather than being a straight cut edge, the edge was rolled. Technically it might not need the metal shim, but that rubber washer is important for sealing. The shim may also be needed to create the proper squish on the o-ring.

If the o-ring looks perfectly round, then it's pointing to the fact that the setup in your bike is not correct. Without proper pressure on that o-ring, oil can bypass the filter and go straight to the sump or at its worst, reduce the oil pressure inside the engine.

This is what the parts look like coming out of my /7. Note I'm using a gasket in order to adjust the squish on the o-ring.

Kurt

There was no shim that came out of my bike.

ME 109 wrote: ↑Wed Jun 19, 2024 1:00 am It appears the shim is ass about, should go in before rubber o ring.
Being ass about won't cause an external leak, but might cause an engine killing internal leak if the o ring is cut by the end of the tube.
Hmmmm, I didn't think later bikes after '85 used a shim?

No shim came out of the bike.

That o-ring isn't compressed at all and should be after a few 1000miles.
I thought that was a shim under the black o-ring in your pic Eyesight might be defective. If so, it should be on the other side if needed for the year model. Apparently not though.