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

[Steve Mills]

Classic master cylinder failure- the brakes will eventually start to
self-apply as the car warms up. Makes for very challenging driving in
traffic after a while.

Steve

On Fri, Apr 13, 2012 at 1:17 PM, Thomas Rodriguez <trodri69 at gmail.com>wrote:

> 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
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