The $2000 O-Ring

[Sava66]

I'm sure this article has been discussed at length, but I did a search and didn't see anything on it in these forums.

http://bmwmotorcycletech.info/Oil.htm

I started to read it in preparation for my first oil change, but it was kind of hard to get through because I couldn't picture the parts without ever having seen them.

Can anyone tell me if this $2000 O-Ring is applicable to my bike (1982 R65) and kind of simplify what the trick to not screwing up my engine is? Thanks.

[Air4Life]

Here's another bit that might assist you:

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

[Barry]

Yes it is applicable to your bike.

Anton Largiader's site posted above is a lot more palatable and that's the clearest diagram around but don't worry about the diagram being of an oil cooler type installation. The detail of the shim and the O ring is still correct as in principle is the canister depth table. The other bit of detail you won't recognise in Anton's diagram is the square section O ring which will be a much smaller diameter on your filter.

If you have calipers or a micrometer I advise that you measure the shim, gasket and O ring thickness yourself rather than assume they are the published sizes. Here's my own measurements and decision table.

"Simplify the trick" Well it is simple in principle. The 2000$ O ring has to be under between 0.2mm and 0.8mm compression.  A good visual indicator is that an old O ring should come out somewhat squared off to show it has been under some compression.  If it comes out still perfectly round then that indicates not enough compression and if it comes out with extruded feather edges then that indicates too much compression.

[Bob_Roller]

This is a problem, that has taken on a life of it's own .

Appearantly at some time in the past, the sleeve that the oil filter sits in, was installed at an incorrect depth, too far in .

That led to the large white o ring to not be compressed enough and cause loss of oil pressure .

When you take your oil filter out, look at the o ring, if it is square in a cross section view, you're getting proper o ring compression .

Just make sure when you put things back together, the metal ring goes on first .

[Barry]

Bob's right it should be simple and in the majority of cases it probably is but only recently someone new to airheads had no oil pressure at idle and found the cause was due to a canister depth that had sunk to over 4mm. I think it needed 3 shims to get adequate compression on the O ring.

For that engine at least following the standard instructions without awareness and understanding of this issue would have resulted in disaster.

[leswaller]

Is this problem common to all airheads? Having recently bought an R60/5 which was serviced as part of the deal so I have not yet needed to change the filter. Am I going to have to deal with this issue?

[Bob_Roller]

It's not a real common problem, if your bike has a fair amount of miles on it and the engine is running fine, I wouldn't get paranoid over it .

For peace of mind, do the measurements when the filter gets replaced next .

I would be more concerned of someone not familiar with BMW airhead bikes putting the metal washer and o-ring in incorrectly .

[Barry]

Is this problem common to all airheads?

It's not so much a problem as a poor bit of design that was introduced to facilitate the use of oil coolers and the rest of us were lumbered with it. So no it's not common to all airheads. I think the oil coolers were introduced around the the time of the /7 models. If you have a /5 or /6 with a flat plate filter cover then you don't have the 2000$ O ring. There's another cover behind that plate and filter replacement is fairly straight forward.

[tvrla]

Appearantly at some time in the past, the sleeve that the oil filter sits in, was installed at an incorrect depth, too far in .

From what I've read, the canisters weren't necessarily installed too deep, more like they can migrate away from the cover.  They might be fine for the first 60K of their lives, then suddenly start sinking.

[leswaller]

Thanks Barry, so with my SWB /5 I can forget it and not get paranoid when I change the filter