[Vwdiesel] brake servo

[Dianne Roa]

I have a 1984 VW Rabbit *diesel*.  When I push the brake pedal down, there
is a hissing sound.  The first time I push the pedal down, the brakes work
fine.  If I pump the brakes several times, the vacuum assist from the brake
servo goes away.  I put a vacuum pump on the brake servo input.  I created
a vacuum on the brake servo and it gradually leaks down.  Also when I put
the vacuum on the servo I can hear a slight leaking sound.  If I put the
vacuum on the servo as soon as I push the pedal down it goes to zero.  I am
not absolutely sure if the problem is with the servo or the vacuum pump.

Bob Roa