Grotty Clutch Fluid on My Oilhead BMW

[Shaun the Fatman]

OK my turn to ask for help: The clutch activation rod on my R1150 enters the transmission and pushes against the car-type clutch between the Engine and the gearbox. The activation rod being pushed in by a "slave" cylinder worked the same way a brake caliper is.

I've bled the system several times, and then replaced the master cylinder piston and bled some more, but the same thing keeps happening...after 100-150 fast miles the clutch fluid turns to soup and I have to pump the clutch lever to get any pressure.

I'm suspecting the heat and vibration is letting the transmission oil seep past the felt seal around the rod. What I'd like to know is, even if that was happening, would it be possible for the transmission fluid to get into the clutch fluid? Anyone experienced something similar?

There's no sign of leaks, the clutch and transmission fluid are not changing levels etc.

I was hoping it was just me not finding and cleaning all the gunk out when I replaced the master cylinder piston, but now I'm suspecting there's a dodgy sphincter somewhere. Grateful for any (anatomically possible) suggestions.

[johnr]

arent the clutches on the oilheads dry? if so how would gear oil get into the clutch? isnt it possible that a seal had gone kaput somewheree and the clutch is in fact drawing air into the system and this is emulsifying the fluid? had a similar problem on a mates jam fj12. the slave cylinder seal was pulling air in. no fluid leak so it took us ages to figure it out. i suppose that a clutch isnt under the same pressure as a brake cylinder, so it might not leak if the seal was worn, or the cylinderbore was worn. it might even be the master cylinder on the bars pulling in air or rainwater?

[Shaun the Fatman]

Yer the clutch itself is a dry clutch, but the actuation rod (I think) has to go through the transmission to hit on it. When the clutch lever has hydraulic pressure the clutch itself works fine, so not worried about that.

Had transmission fluid leak for my K100 in a similar way, out past the clutch actuation gadget on the back of the gearbox, but as that was a cable-activated clutch, it was an isolated problem and easy enough to fix.

Could be a semi-dodgy slave cylinder like you say, all the joints look tight and dry. My only other thought is that the old worn Master cylinder piston let crud in, that I haven't entirely flushed out yet.

I'll keep on bleeding the system for the time being, to see if gets any better. Otherwise it's into the Shop for a strip down. The slave cylinder's a bugger to get at and that's a part I would have to replace rather than fix, so may have to fork over wads of cash to BMW Mottorad.

[kitkatman]

had a similar problem on a mates jam fj12. the slave cylinder seal was pulling air in. no fluid leak so it took us ages to figure it out. ?
the problem i have had on the fj12 is that on the slave cyclinder there is a rubber sleeve and tha the clutch oil was leaking past that.....i took the rubber off and gave the slave cylinder a good scrub up and then repace the rubber and used some of that rubber sealant stuff you can get from halfords...i did that 4-5months ago and i hav'nt had any problems since ( touch wood) and the clutch has kept the same pressure.....it was a pain in the arse to find as the clutch oil that was leaking was collecting in the slave housing....

[pyro]

the problem i have had on the fj12 is that on the slave cyclinder there is a rubber sleeve and tha the clutch oil was leaking past that.....i took the rubber off and gave the slave cylinder a good scrub up and then repace the rubber and used some of that rubber sealant stuff you can get from halfords...i did that 4-5months ago and i hav'nt had any problems since ( touch wood) and the clutch has kept the same pressure.....it was a pain in the arse to find as the clutch oil that was leaking was collecting in the slave housing....

Did you not get the other one?



after 100-150 fast miles the clutch fluid turns to soup and I have to pump the clutch lever to get any pressure.

Either air being sucked in past a seal or there is water in the system, did you clean out the slave as well? I would drain the whole thing, check the rubber seals at both ends and refill with fresh fluid, use a syringe to push fresh fluild UP the system, that works well but remember to put a cloth around the master or fluid will go everywhere.

[Shaun the Fatman]

Either air being sucked in past a seal or there is water in the system, did you clean out the slave as well? I would drain the whole thing, check the rubber seals at both ends and refill with fresh fluid, use a syringe to push fresh fluild UP the system, that works well but remember to put a cloth around the master or fluid will go everywhere.
Couldn't get to the slave cylinder as it's buried beneath the exhaust and swinging arm (which is why it has a bleed pipe, it's hell to get to for a simple operation like that).

I've tried that syringe trick on my Brakes after forgetting that pumping the handle with ABS switched off don't give it enough, and trying to bleed it with the power on pumped out ALL of the fluid in the ABS modulator in a sort of hosepipe effect..which I couldn't then top up from the handlebar reserve.

After a frantic wash-down of the fairing had a go squeezing some fluid back up the pipes to eliminate the flashy ABS warning light screaming "Blue Murder" at me. I now have decent brakes (may be some air in there still) but reluctant to try it again on the clutch, as you say it was a messy operation.

Got a vacuum bleeder on order from ebay, if the post will ever decide to deliver again. I'll try that on the Clutch as well as the Brakes, but if it comes to dismantling the bike to replace the pipes or crush washers I'll wimp out and get the BMW guys to work on it. That's the price I pay for not having a Garden shed, or a garden for that matter.

[John Hopkins]

If the fluid is turning to soup after only 150 miles, but the level is not changing and the soup is dark and dirty it must be a knackered rubber seal or the inside of the hose is rotting away...you havent got a hose up against something hot have you...

[pyro]

You could always sell it and buy something decent.... :p

[Shaun the Fatman]

Oi Behave.... first bike I've ever taken to 130, with ME on it and 2 weeks worth of camping gear. :p

I think it is some sort of seal/pipe failure, but checking out some of the BMW sites, theres a few reports of my original thought: transmission oil leaking into the slave cylinder causing it to fail or worse, creeping back up the slave rod onto the clutch... Mega Bucks to get that fixed.

I'm now wondering if the gear oil got extra slippy cos I added Molybed..molybdem,...er.. gear oil additive to it, that crippled my old sportster by making the press-fit starter motor ring slip...swapped out the oil for fresh to be on the safe side.

I'm beginning to think I shouldn't do that kind of research, it's like a hyperchondriac reading one of those Home Docter books
:confused:

Damn post strike, I still aint got my vacuum bleeder so It's just sitting there at the moment. I'll run it up the M11 tomorrow to see if the same "soupy fluid" problem happens.

[kitkatman]

Did you not get the other one?





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yes mate, but that was before then