R1100GS rear crank seal frustration

[Latman]

On finding there was oil leaking from my rear crank seal, I gathered the courage and have recently replaced my inner and outer crank seal, along with clutch plate, however, after a 40 mile test ride .... oil continues to leak ...

So, I tear the bike down again, ordered new outer seal, clutch and flywheel bolts and replace outer crank seal again ... another 40 mile test ride ..... another oil leak ...

I used the most careful of seal seating methods not involving the special BMW tool, using all the advice I could gleen from here and advrider to oil and ease the seal in with inner lip inward and seat it nicely both times. There were no rough spots on the crank or crankcase surfaces to mash the seal.
The transmission input shaft seal is not leaking - that was suceessfully changed as a prophylactic measure.

I have no independent BMW specialist mechanics in my area to send it to, only the BM dealer ... but that would be last resort ...
Im at loss as to the solution ...

 

[Posh Pete]

Daft laddie questions: is the oil level correct and are you using the correct specification oil?

 

[Magnon]

Daft laddie questions: is the oil level correct and are you using the correct specification oil?

Daft laddie questions V2: Who's supplying the seals and are they Kosha / Pukka items ??

 

[Latman]

Yep, oil is to spec and seal nr1 came from Motorbins, nr 2 from Motorworks.
Asked the same question on advrider and up came an interesting theory worth investigating:

"is it possible that the engines crankcase vent is plugged or pinched off?"

 

[Posh Pete]

Sound suggestion. A lot cheaper and easier than replacing yet another seal!

 

[uncle dick]

Yep, oil is to spec and seal nr1 came from Motorbins, nr 2 from Motorworks.
Asked the same question on advrider and up came an interesting theory worth investigating:

"is it possible that the engines crankcase vent is plugged or pinched off?"

That was my first thought. IIRC the breather arrangement changed halfway through 1100 production. The 'valve' was built into the front timing cover. Later bikes did away with it. Easy enough to check though, just take the pipe off the airbox and see if it chuffs a bit when running.

 

[Latman]

Just got around to trying to check the crankcase ventilation.
Looks like I need to got through the whole procedure of lifting the rear sub-frame and get the airbox out again to do it .... or there a short cut?

 

[uncle dick]

Just got around to trying to check the crankcase ventilation.
Looks like I need to got through the whole procedure of lifting the rear sub-frame and get the airbox out again to do it .... or there a short cut?

What are you actually trying to do - remove the airbox, or just the pipe?

 

[Latman]

I just removed the end of the breather hose from the box, started it up and it pulses air through the hose, so breathing seems to be OK. Back to drawing board...

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