Agreed.  Had this happen recently with my 1980 Mercedes.  It would fail at the stoplights, drop the pedal, and would slowly creep forward (automatic transmission).  Then when the car moved (light turned green), it became normal (pressure built up again).  Eventually, I started the car one morning and it wouldn't stop so badly that I had to stop.  Fluid looked good but brownish (old should be changed).

  Changed the master cylinder, bled brakes and all is well now.

  Do this quickly.  This is a symptom of impending concern.

dooley <pdooley@GTE.NET> wrote:
  The problem is definitely the master cylinder. Intermittent behavior is a
classic symptom. It will only get worse.

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Mike Collum
Sent: Saturday, July 29, 2006 9:21 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Brakes oddness

The master cylinder exibited this exact behavior in my '84 a number of
years ago. I changed the crappy brake fluid and haven't had the problem
since (same master cylinder).

YMMV

Mikel
Houlton, Maine

Edward Maglott wrote:
> Master Cylinder. The rubber seals in there sometimes exhibit this
> sometimes sealing, sometimes not symptom. Especially likely if you find
> the level of brake fluid is not dropping.
> Edward
>

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