[s-cars] Brakes seize up when engine is warm

[Thomas Rodriguez]

The brakes in my '95 S6 started malfunctioning yesterday and I need
some advice on the potential cause.

The brakes perform normally when the car is first driven from a cold
start.  As the entine warms up the brake pedal engages earlier and
earlier until finally there is no play left at all.  At this stage the
brake pedal becomes very hard and grabby as though it's getting way
too much boost. If I continue to drive I can feel the brakes engaging
on their own with progressively more pressure the longer I drive.
Eventually the braking pressure becomes so strong that the car cannot
be driven without smoking the brakes.  If the car is allowed to sit
for a while and cool down the brake function returns to normal.

When this happened yesterday the brake system warning lights lit up on
the dash board.  The owner's manual instructed me to check the level
of the brake fluid and hydraulic fluid.  I did this and found the
brake fluid level to be fine but the hydraulic fluid level was way
below its "low" mark.  I topped up the hydraulic fluid which took care
of the warning lights on the dash board but the brakes still seized up
the next time the car was driven long enough to warm up.

The car is currently parked until I figure this out.  I would
appreciate advice from anyone who has dealt with this sort of thing.

Thanks, Tom
'95 S6