Confused about the $2000 O-ring

[GregL]

Recently I've been hearing horror stories about the $2000 O-ring and reading a lot of articles about how to set up the filter/shim/o-ring/gasket arrangement. My 1981 R100 has never had a shim (I bought it new and have done most of the oil changes, including the first one), even though it has the canister without the rolled edge and supposedly should use one. I've also never seen a white o-ring... mine have always been black. I'm putting the bike back on the road after many years of little use and have been catching up on the service items that have been put off, including clutch spline lube, steering head bearing lube/adjust, pushrod tube seals (2nd time), etc. Having had the cylinders and heads off, I've had the opportunity to examine the cylinder walls, pistons, valve train, etc. At 94,800 miles wear appears to be nearly nonexistant, so I don't think I've ever had an oil supply/pressure problem. Nevertheless, due to concern over this o-ring issue, I decided to remove the cover gasket (supposedly not needed anyway) to provide more "crush" on the o-ring, as it shows signs of making contact with the canister, but not by much. I started the bike, and by the time I got the choke off and looked down, there was about a quarter cup of oil on the ground, running, not dripping, out from behind the now gasket-less cover! Apparently, in my case anyway, the gasket is needed.

I'm not going to run the bike again until I can locate one of these white o-rings, which are supposedly 4 mm in thickness (my current black one is about 3.7 mm). I'm wondering if I should also add a shim, even though I've never seen any damage to any of the o-rings?

Any thoughts on this would be appreciated.

[krehmkej]

You didn't mention if yours is equipped with an oil cooler. There are differences on those that do have it. Assuming that you have no cooler installed, looks like you have dodged a bullet.

Cannister depth on your engine is probably shallow enough that you were able to get enough oil pressure. I would certainly get the kit with filter, o-ring shim and gasket included.
I use a kit from NAPA, part #PS4945. Has it all included. The o-ring in it is the correct white one. My cannister depth is such that I use the shim and gasket to get the proper crush depth.

Really need to measure the cannister depth with a vernier caliper then determine what you need to do to get the proper crush.

Anton's article:
http://www.largiader.com/tech/filters/

Has all you need to know on the subject.

[20774]

Definitely a confusing subject...not sure where you've read things, but Anton has a good summary of all the systems as well as how to determine what you need to reinstall.

http://www.largiader.com/tech/filters/

Snowbum also has quite a write up, almost too much to absorb.

I'm assuming you don't have an oil cooler...I'm only familiar with bikes that don't have it...not sure how it affects things, but Anton describes things.

Basically, you really want the white o-ring. This is what does the sealing. I'm sure you've seen the internal canister within the engine block. It's set back from the outside surface of the block. Nominally, this canister (the sharp edge of it) is set back 3-3.5mm. You should try and accurately measure that distance. That will tell you what additional stack up parts you need.

If the canister is nominally the above depth, I was suggest the white o-ring and one metal shim.

If the canister is less than 3mm (mine is around 2.8mm), then you should add a paper gasket under the cover. This moves the cover out a tad and reduces the crush on the o-ring. That's my current setup - o-ring, one shim, one gasket.

If the canister is deeper than 3.5mm, you're probably in need of one or more extra shims, and no paper gasket. This is where the measurement comes in. You can do the math to figure out how many shims you might need.

The goal is to get between 10 to 25% crush on the white o-ring. Less than 10 and you're in danger of letting oil bypass the canister resulting in much less oil pressure. More than 25 and you're in danger of splitting the o-ring resulting in oil bypassing the canister and much less oil pressure.

HTH....

[GregL]

Thanks for the informative replies. You're both correct in that it's a non-oil cooler model. I have read both Anton's and Snowbum's articles. My canister depth measures approximately .132", or about 3.3 mm. My black o-ring measures 3.6 to 3.7 mm. As I mentioned, I'm going to have to use the gasket, unless the larger cross-section of the white o-ring (4mm) will also seal the cover to the engine case.

I've ordered the PS4945 filter kit from my local NAPA (thanks for that tip also) and will know more when it arrives.

[20774]

My canister depth measures approximately .132", or about 3.3 mm. My black o-ring measures 3.6 to 3.7 mm. As I mentioned, I'm going to have to use the gasket, unless the larger cross-section of the white o-ring (4mm) will also seal the cover to the engine case.

GregL -

Your description of the black o-ring thickness and using gaskets is counterintuitive. The black o-ring is not thick enough. Putting a gasket on the outside cover only serves to move the mating surfaces farther apart, thus reducing the tension on the o-ring. The gasket is designed to provide an oil seal between the cover and the block. But in doing so, it physically spaces the cover further away from the internals of the filter, thus resulting in less compression on the o-ring.

Your 3.3mm canister depth is something close to nominal. I would think that with the white o-ring, you would use one shim and no gasket.

Here's some numbers, provided by Oak in an Airmail magazine a number of months ago.

- o-ring thickness = 4mm
- shim thickness = 0.3mm
- gasket thickness = 0.5mm
- canister depth = 3.3mm (your number)

Doing the math, one white o-ring and one shim results in 25% compression...perfect. Add the gasket and the compression drops to 12.5%. Do not use the gasket!!!!

Take the black o-ring thickness you mentioned - 3.7mm. Redoing the math for black o-ring and one shim results in about 19% compression. Using the gasket drops it to a dangerously low 5.4%.

Get the proper o-ring, use one shim, and ride it. Next time you change, you should see a reasonable squaring-off of the white o-ring. That's a good indication you have a suitable amount of compression.

[GregL]

Kurt, I understand what you are saying, and it makes sense to me, but when I see a 3" wide puddle of oil on the ground in 10-15 seconds, I must conclude that, in my case, the gasket is a necessary thing. Even if the use of the 4mm white o-ring seals the cover to the crankcase, preventing external oil loss, the whole thing seems shaky at best. External loss of oil will be no less catastrophic than internal loss of oil pressure, therefore I will be inclined to use the gasket, and if necessary, two shims instead of one to provide the necessary crush of the o-ring.

[Dennie]

never seen one leak like that, anyway my gs needed 3 shims, have you seen the price on that cover? wow

[AntonLargiader]

... External loss of oil will be no less catastrophic than internal loss of oil pressure, therefore I will be inclined to use the gasket, and if necessary, two shims instead of one to provide the necessary crush of the o-ring.

If you are leaking oil with only 3.3mm canister depth, you have a separate problem that you DON'T want to hide by sealing the cover to the block with a gasket. Most likely the O-ring is cut.

[20774]

If you are leaking oil with only 3.3mm canister depth, you have a separate problem that you DON'T want to hide by sealing the cover to the block with a gasket.

+1...The gasket was needed on the /5 and /6 oil fiter setups where the sealing was done with internal o-rings. The cover gasket was needed for leaks past the cover. But with the new setup, the gasket is really only needed for a spacer. So I agree that something else is going on, possibly a warped cover or gouges in the engine block or the cut in the o-ring as suggested. You're nominal canister depth should be fine with no paper gasket.

[GregL]

Anton, thanks for your response.

I suspect that the separate problem is the black O-ring, with it's smaller 3.6mm cross-section. It's sealing the end of the canister (barely), but not being crushed enough to expand out to seal the block and prevent pressurized oil from leaking out the cover. I just checked, and my owner's manual says "Install new O-ring on center pipe, put new filter element and sheet metal ring inside oil filter housing, put new paper gasket, small and large O-ring on cover".... the diagram seems to show the older configuration with separate filter end O-rings. As I recall, all of the filter elements I've used had the seals on them and no separate O-rings were needed... and yes, I checked... there's no left over O-ring down on the center pipe.

The NAPA filter kit will be in today... I'll know more after that.

[GregL]

Well, I just returned from picking up the NAPA filter, only to find that the shim is not included, only the white O-ring, which does measure 4mm, and a paper gasket. It's surprising that that gasket is always showing up, even though it's supposedly not needed and the shim always is if you have a canister without the rolled edge.

I'm still nowhere on resolving this issue for now... it's either order online and wait, or 200+ miles roundtrip to the BMW shop.

[Kirbster919]

Sorry to revive an old topic, but I have a question relating to it. I just changed the filter on my 1986 R80 for the first time (bought it in the fall, changed the oil but left the filter, since it was just for storage's sake and I couldn't get a filter in time).

The old filter was installed with the white o-ring, but no shim and no paper gasket. In my haste, I ended up slightly bending my shim, but it seemed pretty true, so I laid it on a table, put a book over it, and then installed it. I started the bike up and oil leaked out, so I knew something was wrong. Well, it turns out that the shim cut the o-ring.

I had to get the bike buttoned up for the week, so I improvised. I installed the old o-ring, with no paper gasket and no shim. The oil light isn't on, so I know I have at least some pressure. No oil is leaking anymore. With this setup, according the earlier linked websites, I'll have .15mm of extra "crush" on the o-ring than with the shim and gasket.

While this setup isn't ideal, this bike is my only source of transportation. I think I'm probably safe to ride this bike to the BMW dealership to pick up the part. Does anybody have any opinions?

[20774]

Question...what is the depth of your canister? Knowing that and the various stackup lets you determine the exact amount of o-ring compression.

Question...does you canister have the rolled edge? I forget which years they used that. If you have the straight sharp edge on the canister, there's a real danger of cutting the o-ring on that edge.

Are you sure the shim cut the o-ring? That seems hard to do, unless it was severely mangled in which case it would be wise to have used it at all. Maybe the o-ring was just pinched somehow...

[osbornk]

If you have ridden the bike 94,800 miles with your current procedure and no apparent wear or other problems, I wouldn't worry a lot about it. What you are doing now must work. My shim is so thing, I don't think the presence or absence of it would make enough difference to matter. both the o-ring and filter have plenty of room for variation.

[jforgo]

I stock extra white Orings, and save the old shims. i do the measurement as shown in the recent ON article. I figure having the extra shims and white Orings leave me prepared for any issues, or changes in canister depth.

There is a sharp side to each shim - always make double sure this is facing towards the engine!

[alkoivisto]

[QUOTE=osbornk;446484]. My shim is so thing, I don't think the presence or absence of it would make enough difference to matter.


I'm thinking leaving the shim out if math calls for it is courting disaster as the shim is sealing surface for canister side of O-ring the way I see it !!

About three years ago after oil/filter change, I started up motor and oil pressure gauge installed year prior showed nearly zero psi at idle and maybe 20 psi max on throttle. To make long story short, the new OEM BMW white O-ring section diameter was smaller than that of Emgo white O-ring section diameter. New BMW part was undersize. Re-assembled with extra Emgo O-ring and oil pressure good. What I do now is pre-install filter cover using O-ring and shim only leaving filter and paper gasket out. I look for about 1/16" space between cover and engine block with O-ring un-compressed or press cover in and it should spring back out that 1/16". Adjust shims/gaskets as required. If good re-assemble with filter and paper gasket. Works for me anyway.

Install of oil pressure gauge is cheap insurance as oil pressure sender only lights off idiot light when disaster is in progress in my opinion. I located mine in place of inoperative clock.

Oil pressure gauge was installed following potentially catastrophic O-ring problem. Luckily big end rod bearings survived 1500 mile ride home with container of STP added to oil when tell-tale knocking began. Idiot light gave absolutely no warning, even at hot idle. I now always inspect oil filter after use. Any shiny bits, especially tin coating and copper(!!!) base from rod bearings should be cause for alarm.

[Manfred]

Install of oil pressure gauge is cheap insurance as oil pressure sender only lights off idiot light when disaster is in progress in my opinion. I located mine in place of inoperative clock.

Details, please. Sending unit is where?, etc.

Thanks!

[sportridertex]

The bike has been working great for all these years,and you have to go and muck with it.....

More riding, less reading......
;)

[jforgo]

[QUOTE=osbornk;446484]. My shim is so thing, I don't think the presence or absence of it would make enough difference to matter.



The shim is always needed to fill the openings around the circumference of the canister. if your clearance is below norm, I believe the solution was to add the outer gasket with the 3 holes, which is not normally used on later bikes.

[alkoivisto]

Details, please. Sending unit is where?, etc.

Thanks!

Idiot light sending unit located lower left side of engine block just below pushrod tube seals. Similar in appearance and function to neutral switch.

[20774]

The shim is always needed to fill the openings around the circumference of the canister. if your clearance is below norm, I believe the solution was to add the outer gasket with the 3 holes, which is not normally used on later bikes.

The gasket was used on the early bikes with the filter which had the internal bolt to tighten...the outer cover to the case was generally flat. The gasket was needed in order to prevent seepage. The only reason to use a gasket in the later bikes is if the internal sharp-edge canister is too close to the outside of the engine case. If this is the situation, the gasket's sole purpose is to move the filter cover out in order to not completely mangle the o-ring. It's job is really not for dealing with oil seepage as that is the existing white o-ring's job.

[alkoivisto]

The gasket was used on the early bikes with the filter which had the internal bolt to tighten...the outer cover to the case was generally flat. The gasket was needed in order to prevent seepage. The only reason to use a gasket in the later bikes is if the internal sharp-edge canister is too close to the outside of the engine case. If this is the situation, the gasket's sole purpose is to move the filter cover out in order to not completely mangle the o-ring. It's job is really not for dealing with oil seepage as that is the existing white o-ring's job.

Yup. My R100 had gasket in place when I bought it and I've just now had one of those "Doh!" type realizations in that gasket being in place created a borderline/deteriorating oil pressure condition per my earlier post.