Hydraulic system problems ('85 5000 turbo)

[Douglas Fifield]

All,

If the servo is completely toast, it will not charge the accumulator
at all.  The car will drive, the brakes will work (in a fashion), but
the accumulator will not charge.  The brake pedal is as hard as a rock
as soon as the engine turns off.

D.

On 8/18/06, Kneale Brownson <kneale at coslink.net> wrote:
> At 11:16 AM 8/18/2006 -0400, Ameer Antar wrote:
>
> >
> > The only other weak point I can think of is the brake accumulator; this was a
> > rebuilt one. Could this be causing these symptoms? Any more advice or
> > diagnosis procedures is much appreciated.
>
>
> The test for the accumulator is to run the engine above an idle (like after
> you've driven far enough to warm up the hydraulic oil well), shut off the
> engine and pump the brake pedal repeatedly until you go from a normal feel to a
> stiffer feel.  Anything under about 20 pumps indicates a failing accumulator.
> Anything under five pumps indicates a dead accumulator.
>
> There really is no "rebuilding" in the sense of taking the sphere apart and
> replacing the bladder that flexes to compress the nitrogen gas on one side of
> it while the oil is under pressure and then holding that pressure for use as
> the brakes are applied without the engine running.  A bad valve that releases
> pressure prematurely can be tested for and replaced and the bladder can be
> tested to be certain it holds a charge for a while, but it's impossible to tell
> that the bladder might let the gas escape over a month or so, I'd think.  Or
> might just fail shortly after being put back into service.
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-- 
Douglas in MN
95.5 Audi S//6 Avant
73 BMW R60/5 mit Toaster Tank