R100S oil change

[20774]

So , If you screwed this up badly would the low oil pressure light come on? With the light off can you still risk toasting your engine?

I'm not totally sure, but here's what I think might go on. Normally, the oil fills the canister area and flows from outside the filter into the inner core going through the paper, and from there it gets pulled through the engine. Snowbum has diagrams of the oil flow here:

http://bmwmotorcycletech.info/oilsketch.htm

There is high pressure in this region...there have been instances of collapsed oil filter elements. At any rate, the oil finds the least restrictive path to the rest of the engine...generally that's through the filter element, but it could be through the pressure relief valve in the base of the canister area. All that should be good.

If the o-ring is cut, what will happen is that the oil finds the path of least resistance which would be past the o-ring straight into the sump. So, the oil being pumped through the engine is unfiltered. This is what will destroy the engine along with the lowered pressure to critical bearing surfaces. Don't know if the oil pressure light will come on...it only comes on with very low pressure but I think in the situation of o-ring failures, the pressure doesn't drop significantly, it's just unfiltered.

I'm certainly open to corrections on this...but that's what I think is happening.

 

[toooldtocare]

So , If you screwed this up badly would the low oil pressure light come on? With the light off can you still risk toasting your engine?

I’m one of those that screwed up the white O ring. The bike was a 1995 R100RT. I changed the oil on a very cold day. A few days later, after a ride to an Airhead Tech day where I helped others, I noticed oil on the pavement under the bike. Since the bike was a 95, the shim was not required and the dept of the canister did not require the paper washer either. I had pinched the O ring, almost cutting it in half. The oil light did not come on, and the engine suffered no damage. I proved that over the many thousand miles that I continued to ride that bike with no problems.

Moral of the story is, if it feels like the cover is not going on right, stop and look to see what the problem is. I blamed it on the sub freezing day, not on me messing up.

Wayne

 

[lkchris]

Sorry, on your '77 you need the shim. Its purpose is to protect the o-ring from the sharp edge of the filter canister and frankly simply to give the o-ring something to seal against.

In the mid to late 1980s, these engines began to feature filter canisters with folded over edges that provided the flat surface required for o-ring sealing and protection. You didn't need the shim on these models.

I'd be interested to see official BMW publications addressing the need for shims to adjust for canister depth ... most of this is I think and invention of a few gurus and I can say I've never seen the need.

No, you don't use the paper gasket on anything newer than a /6.

 

[20774]

No, you don't use the paper gasket on anything newer than a /6.

Kent, I know you've said this is the past and generally it might be true. But I can attest that in my situation, with a canister that is somewhat close to the engine surface, I need a gasket, in fact I run two gaskets, in order to shift the cover away from the block to allow room for the o-ring to reside without getting super crushed. Yes, I use the metal shim. So IMO it is not a universal statement that anything newer than a /6 doesn't need a gasket. To borrow a thought from the past, "Trust but measure to verify."

 

[beemerphile]

Proper o-ring compression is necessary - even if you have to break some "rules" to achieve it.