Brake fluid overflow (R1200GS)

[Mouse]

I was cleaning my brakes the other day, and I noticed that when I pushed the pistons back into the caliper (gently of course) a load of brake fluid pissed out of a tube under the seat.

The bike has just had an annual service, which involves changing the brake fluid in the wheel circuit. As the pads are quite worn down, I'm assuming that the technicians overfilled the reservoir, thus causing it to overflow when I pushed the pistons in.

Am I right? Is this a normal occurance? The brakes and ABS appear to be working fine, but is there anything I should check to be sure?

Also, does this mean that the brake fluid reservoir is open to the air (via the overflow tube)? Or is there a valve of some sort?

Cheers for any advice.

 

[sproggy]

There is a min/max level indicated on the master cylinder. This is irrespective of pad wear so as the pads wear and the pistons move out (in?) to take up this wear you will need to top up the fluid accordingly. But not by much. If the fluid was topped up to the 'max' with worn pads, pushing the pistons back in to fit new pads (or to clean) might make the fluid overflow. I'm not sure of the arrangement on the 1200 but can say for sure that the reseviour would definitely NOT be open to the air. There may be a valve and an overflow, but you should still check that the fluid level is somewhere between 'min' and 'max', preferably the latter to allow for it to drop as the pads wear.

Make sure you wash any spilled/overflowing fluid off all components using fresh water as it will strip paint off anything it sits on.

If you re-fitted the worn pads your fluid level is probably too low now since you've lost some - top it up asap.

 

[Mouse]

Surely the difference between 'min' and 'max' on the reservoir would be enough to cater for the full range of brake pad wear?

What I'm really wondering about is how this might have affected the servos and ABS ... the reservoir in question is the servo reservoir that's hidden under the tank somewhere - I'll have to remove the tank and take a look at it.

 

[sproggy]

Surely the difference between 'min' and 'max' on the reservoir would be enough to cater for the full range of brake pad wear?

It might be, but I'd never make that assumption.

What I'm really wondering about is how this might have affected the servos and ABS ... the reservoir in question is the servo reservoir that's hidden under the tank somewhere - I'll have to remove the tank and take a look at it.

Do you really have to remove the tank to check the fluid level? I can't believe that BWM were that stupid when they designed the bike.

There is almost no chance at all that you caused any damage to the servo or ABS just by losing a little fluid - I assume there's a diagnostic facility as there is on my Rockster which would flash a red light at you if there was a problem, and dangerously low fluid would be the first thing it would look at. Presumably the bike still rides/stops the same? No offence, but you're probably being a bit paranoid. If everything seems normal then it probably is.

 

[Tobers]

I did the same and got a small puddle of brake fluid under the bike - about 2 teaspoons worth I reckon. There must be an anti-backflow valve thingy under there somewhere.

No ill effects though.

 

[Mouse]

Do you really have to remove the tank to check the fluid level? I can't believe that BWM were that stupid when they designed the bike.

As far as I know, but I'll investigate properly later

There is almost no chance at all that you caused any damage to the servo or ABS just by losing a little fluid - I assume there's a diagnostic facility as there is on my Rockster which would flash a red light at you if there was a problem, and dangerously low fluid would be the first thing it would look at. Presumably the bike still rides/stops the same? No offence, but you're probably being a bit paranoid. If everything seems normal then it probably is.

I fully agree I'm being paranoid! The bike has shown no abnormal warning lights etc and the brakes work just fine.

Better safe than sorry though