Disappearing (and reappearing) BRAKES

[Kneale Brownson]

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At 12:14 PM 05/19/2002 -0700, amz at eskimo.com wrote:

>Had a strange thing happen to me yesterday.  Got car back from the shop
>(clutch master replacement) on Friday.  Drove it for a few hours on
>Saturday.  Brakes worked fine.  A little while later, the brake pedal seemed
>to depress a bit lower than usual, but car stopped as usual.  Suddenly,
>while driving in slow/stop-and-go traffic, the brake pedal went straight to
>the floor.  Brakes DID apply at the very bottom.  However, car was only
>going about 20 mph at the time.  Tried pumping and nothing changed.
>
>Since I had 20 mph braking and thinking that I might have lost brake or
>hydraulic fluid, I slowly drove to the Audi dealer that (luckily) was a mile
>down the road.  By the time I got there, the brakes engaged with the pedal
>halfway down.  A check under the hood showed full fluids.  I tried pumping
>the pedal again and the top "half" just caused a slight hissing sound and
>the lower half of the pedal gave full braking.
>
>With the brakes improving (and not wanting to pay the dealer to diagnose the
>problem), I took back roads to get home.  A couple of miles from the dealer,
>the brakes returned totally to normal.  Car is back at the mechanic, but
>(without popping the hood yet) they're initially stumped.
>
>What the heck is/was going on???

I'd ask whoever replaced the clutch MC how they bled the system.   Since
the clutch shares the brake system fluid supply, it's possible they did
something to that system.
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