Hoping someone can help, take a look at this

This is a jar of relatively new Dot 4 brake fluid from my bake brake master cylinder. Blakey pointed it out to me on our trip. The front brake master was filled at exactly the same time and is perfectly clear.
Question? Do the gurus think I may be having a rubber hose breakdown or something. I have replaced the braided line by necessity a while ago but just used rubber brake line from a garage. I was finding the back brake unresponsive, there has been no leakage and if there was water I thought it would be whitish.
I was just thinking that I was getting back on top of the repair schedule. Must be port time
RT.

The only thing I can think of is a breakdown of the rubber hose.
Keep an eye on how it takes to turn that colour again (assuming you have replaced the fluid).

hey rt ...was it only a refill or was it a total bleed through.?
had a smilar issue this year after bleeding but i didnt bleed it all out so was basically a top up ......different oils though... really wierd thing (was clutch in the car)

Definitely not a good colour for brake fluid. When flushing the cars and bike through every year I alternate between the super blue brake fluid and the clear. That way you can quickly see when all the old fluid is out of the system and the new stuff is coming through. Not so vital on the K but with some cars with very complex brake circuits like the Volvo 240 series pre ABS there is a lot of pipe and brake bits in them.

So give it another flush and see what the stuff that comes out looks like.
Regards,
K-BIKE

Did the cap not get screwed down enough, or has the internal rubber seal on the cap perished enough to allow moisture and/or road grime to get in?
I would get that outta there and some good clean stuff in quick smart lest the master cylinder and caliper seals cark it prematurely.

Tks, brand new master and bellows so I can only assume the hose is breaking down. I agree that it's definitely a complete bleed out, just one more job. I think I used submersible fuel line for this on reflection
that may be wrong. So far I just siphoned the old stuff out and put new stuff in just to make it look better while I get my radiator fan back.
Cheers RT

Bit of proper hose from BMW won't cost you the bank ;-)

i believe its a chemical reaction rt ...not all brake fluids are the same ..and certainly wouldnt turn all the fluid the same colour other wise.... if it was weepage it would be sitting in the pipes and wouldnt be affecting the whole lot at the resevoir ....

2 cents from an silly old fella

I would definitely not use submersible fuel line in case it causes a problem which it seems it may just have. As soon as possible get some genuine brake hose rated for brake fluid in place of the current and give it a good flush with brake fluid after fitting it.
Regards,
K-BIKE

i agree,use the proper brake line. been a mechanic for almost 40yrs and tend to experiment here and there but not with brakes. that is a life and death item !! it really bothered me when they introduced abs and computer crap to brake systems. mess with anything else on a vehicle but keep the brakes reliable and simple. had a r1150r for a while but them power assit brakes scared me. they worked fine with power,but without power it took both hands to stop, and if they came back on in the middle one would go over the handlebars !!!

Well I've been to Pirtek, a hose specialist here in Oz and bought a metre of special brake hose. (that's how they sell it). So I'll have some spare if anyone over this part of the world needs rear brake lines. Thanks for everyone's help.
RT

I've had some rear brake problems recently and an automotive engineer friend told me that dark brown brake fluid is a certain indicator of water contamination.

Just something of which to be aware.

Paul.