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RE: pulsing brake pedal

From: meck@hutton.net (Jon Meckem)
Subject: pulsing brake pedal
Date: Sun, 1 Jun 1997 18:55:30 -0400
Message-ID: <19970601225526930.AAB239@ppp11.hutton.net>
Sender: owner-quattro@coimbra.ans.net
Precedence: bulk

I just replaced the master cylinder on the 5k, thinking it would help the
pulsing feel in the brake pedal.  It did not.  The symptoms are a spongy,
pulsing feeling as you apply firm pressure to the pedal.  The pedal
eventually stops and gives a firm feel, but not before pulsing for an inch
or two.  Any recomendations?


>First, remove the upper hydraulic line going to the brake servo behind the master cylinder.
start the car and check the servo port. There should be no fluid escaping from the servo with
the system at operating pressure. If there is, the servo is defective.
>Next check the reservoir for aeration of the fluid. If there is aeration, look for the source
of the air to be the front seal of the boost pump(the only place in the entire CHS system where
a suction can exist).
>Next, test the accumulator. Run up the system and shut off the engine. You should have at least
10 power assisted pedal applications before the system goes dead. If not, the accumulator check
valve is defective.

JR North@City Motors