I've got an 855T and it has been loosing brake fluid, though no one seems to know where it's going. No pooling under the car, no visible leaks anywhere. First dealer told me $1880 to replace the ABS master cylinder. I said "thanks, no thanks". Me thinks they wanted to take me for a "ride". My usual mechanic checked over the whole braking system and gave me new pads. Still, a month later I needed to add a little fluid. I keep adding a little fluid every 3-4 weeks.

Any ideas?

JCD

I had a small leak over a period of time, couldn't figure it out until it got worse. It was the EBD (Electronic Brake Distribution) valve. I have it on a 1996 850 and comes out of the hydraulic block or master cylinder (can't remember). There may be a recall on this.

/Pete

I was experiencing loss of brake fluid, wich happened to be the clutch master sylinder. Lie down on the floor and look at the seals around the sylinder, while pressing/depressing the clutch pedal by hand. I had a tiny squirt coming there. The sylinder is replaced as an item, not repaired. It is a tricky job, that I decided to have done at the local dealer. In Norway I paid a little less than 400$.
Later I also had to exchange the ABS sensor, since it was leaking too. A lot cheaper.

Long shot - If a fluid is dissappearing, maybe you are burning it.

If you are losing brake fluid, and can't see it coming out, it could be sucked into the intake manifold somehow via the brake booster.

I'd check the vacume lines for evidence of brake fluid.
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2 8s & 2 7s 633,000 miles total

It also could be leaking off at the calipers and pretty much just "burning" away before you can detect it.
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Brandon
95 854T 92k
Pictures =)