I discovered that the brake pedal goes to the floor this morning. When I moved the car, I noticed that my driveway has some spill spots roughly where the driver's side front wheel was located. I refilled the brake with fluid and it took about 2/3 of the bottle. Pedal still goes to the floor. For the last several days, the ABS light has been on constantly but the brakes seemed to be normal with one exception: I felt something very much like the ABS shudder during very slow stops.

Does it sound like a master cylinder? The calipers were replaced with new (rebuilt ones) about 4 months ago.

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87 300D 265Kmi
Factory rebuilt crate 603.96x engine at 200K