I recently had the enigne block from my 95 R100GS PD vapor blasted. I was in a bit of a hurry and had left the oil filter cover on and forgot to take it off after I got it back. When I opened it a few weeks later I found rust on the canister.
I've ordered a new canister, but there's not alot of info on how to replace it. Snowbum writes this on his website:
YES, it IS possible to, on purpose, move the canister in or out, but I recommend you do not try this, and I am NOT publishing the procedure here ...on purpose, because it is easy to cause damage.
Unless the canister is so rusty that it interferes with it's function, I would avoid trying to move it at all. The chances of 'getting it wrong' are way too high. After all, it lives in an oil saturated environment and is unlikely to rust any more. If it doesn't affect the sealing face at the end of the canister, clean any loose rust off and let it be...
I cleaned off the rust a month ago and applied some WD40 to prevent further corrosion. There's some pitting on the mating surface for the o-ring and inside the canister itself. See pictures below. What do you think?
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I wouldn't worry about that. Try removing a bit more crap with a wire brush and sandpaper and put a new metal shim for the surface the white o-ring sits on. You can get anal and measure the precise canister depth, but it looks fine to my eye.
Mechanic from Hell "I remember every raging second of it...
My bike was on fire, the road was on fire, and I was on fire.
It was the best ride ever!"
I would certanly try to remove loose rust, particularly from the central tube as this is the 'engine' side of the filter. Not too worried about that on the outer canister... it's a filter after all. I would be more concerned about the pitting on the end of the outer cannister (as seen (particularly) in the second image). This joint is a seal under full pump pressure. Since this is one of the late models, which don't use the metal shim at this location, however, there is a good chance that the 'O' ring will take up these pits and seal. I would be inclined to assemble the engine and run it watching the pressure gauge. If there's any sign of low pressure stop and reconsider. It might also be an idea to put an oil pressure tester on it to make sure things are sealing. Replacing the outer canister isn't for the faint hearted...
The filter was actually installed with a shim when I bought the bike. I'll measure the depth when I get back to whe workshop. If I'm not mistaken I should be aiming for about 20% compression.
At first I was quite worried about the pitting on the edge of the canister. However, like Rob says, I believe the o-ring will provide sufficient sealing given the right amount of compression. After all, a shim (or even two) provides adequate sealing and I would imagine that metal-to-metal has lower sealing efficiency.
If it turns out I need the shim to achieve proper compression, would it be a bad idea to put the shim on after the o-ring, so the o-ring sits directly on the canister edge, followed by the shim and the cover?
Merstad wrote: ↑Wed May 07, 2025 1:54 pm
The filter was actually installed with a shim when I bought the bike. I'll measure the depth when I get back to whe workshop. If I'm not mistaken I should be aiming for about 20% compression.
At first I was quite worried about the pitting on the edge of the canister. However, like Rob says, I believe the o-ring will provide sufficient sealing given the right amount of compression. After all, a shim (or even two) provides adequate sealing and I would imagine that metal-to-metal has lower sealing efficiency.
If it turns out I need the shim to achieve proper compression, would it be a bad idea to put the shim on after the o-ring, so the o-ring sits directly on the canister edge, followed by the shim and the cover?
20% is a good target. I'm only familiar with the sharp edged canister. The rolled edge canister was an improvement to the possibility that the sharp edge could cut the o-ring. If you need a shim, I would be concerned about the rough edge of the canister not sealing completely against the shim. Seems like with this later configuration, the shim is not needed for protection but for spacing issues, so putting it on the other side of the o-ring might be acceptable.
There 'should' be no depth issues with the later engines. The problem was only current for a short period and had been addressed by the time the Mono engines were issued. Still worth checking though... who knows what has happened to the engine in the intervening period.
I haven't really thought about it before but I can see no reason not to put a shim between the 'O' ring and the cover if depth is critical and you want to put a bit of extra pressure on the 'O' ring. The seal of the 'O' ring is made by compressing it against the end of the canister, the side of the hole on the crankcase and the inward protrusion of the cover. The contact with the face of the cover, where the shim would go, is not really relevant as no oil should get that far. Given the condition of the face on the canister, I would assemble the cover as it stands without a shim, start the engine (giving attention to the oil lamp... if that stays lit switch off immediately). then I would check the oil pressure with a pressure tester to be on the safe side. Any tendency for the oil pressure lamp to come on with the engine running should lead to further investigation...
I am attaching a copy of the BMW bulletin regarding the canister depth issue. (I don't have a copy of Bulletin 11 004 77 (032R) . if anyone has a copy I'd be grateful if they'd let me have a scan).
Screenshot 2025-05-08 110812.jpg (123.93 KiB) Viewed 724 times
I'll measure and use the shim if necessary to get a bit more compression and follow your advice on oil pressure testing. Just to be sure, 10-15 psi idle should be about right?
