Hydraulic system problems ('85 5000 turbo)

[Douglas Fifield]

Ameer,

We recently went through this over on the S-car group when I had a
brake light stay on, a hard brake pedal immediately upon shutting off
the engine, and a thrumming brake pedal when the engine was running.

Fred correctly guessed the brake servo and gave a detailed description
of how to test that hypothesis.  I don't know how to link to that
thread, but I wound up replacing my servo.  I did a write-up on that
if you are interested.  I don't know how similar my case is to yours.

Let me know if you need to know the servo test procedure.  Fred
obviously can provide that as well.

D.

On 8/17/06, Fred Munro <munrof at sympatico.ca> wrote:
> Ameer;
>
> You may have a bad brake servo. When you run the engine, the brake bomb is
> charged and the reservoir level goes down. When you stop the engine, the
> pressurized bomb discharges through the leaking servo into the reservoir and
> the level goes up. A badly leaking servo will prevent enough pressure from
> building up in the system to provide brake boost - the fluid recirculates
> from the pump through the leaking servo back into the reservoir.
>
> There is a standard test for the servo, but the test is not effective if it
> is leaking so badly that the bomb discharges rapidly . To test a servo with
> a bad leak, remove the return hose from the servo to the reservoir and pinch
> it closed. Attach a hose from the servo return and lead it into a bottle.
> Start the engine. DO NOT APPLY THE BRAKES! If the servo is bad, oil will be
> flowing into the bottle. If it is good, no oil will be coming out of the
> hose. NOTE: Make SURE you remove the RETURN hose, NOT the FEED hose from the
> bomb!
>
> This is based on my fading recollection of the Type 44 hydraulics. I just
> went through this with my UrS6 and FWIR the systems are fairly similar in
> function.
>
> HTH
>
> Fred Munro
> '94 S4
> '97 S6
>
> -----Original Message-----
> From: quattro-bounces at audifans.com
> [mailto:quattro-bounces at audifans.com]On Behalf Of Ameer Antar
> Sent: August 17, 2006 10:56 AM
> To: Quattro List
> Subject: Hydraulic system problems ('85 5000 turbo)
>
>
>
> All, I&#39;m having a major problem with the hydraulic system on my 5000
> turbo. Hopefully someone can help. I&#39;ve replaced pretty much every
> component in the system, including the rack, pump, accumulator (bomb),
> reservoir, all hoses/lines and fittings. The accumulator is one of those
> recharged bombs. The only piece I havn&#39;t changed is the brake servo. The
> problem is after replacing all that, there&#39;s still almost no power
> steering or brakes. The power assist does seem to randomly change. Some
> times I can feel a little assist, but for the most part there&#39;s pretty
> much nothing. Since there&#39;s no power steering or brake, I&#39;m thinking
> it&#39;s got to be something up with the pump or upstream of that... Any
> ways to do diagnosis?
> Also, I noticed that the fluid level in the reservoir changes a lot. When
> the car is off, it&#39;s right about at the max, and when running it&#39;s
> very close to the minimum. Is that normal? I&#39;m pretty sure I used  the
> right banjo bolts b/c this system uses crush washers instead of o-rings. I
> believe those pumps only use one type of bolts. Are the pumps different for
> the o-ring vs. crush washer systems? The reason I ask is because the pump
> doesn&#39;t have a tag on it.
> &nbsp;Thanks for any advice.
> &nbsp;
> -Ameer&nbsp;
>
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-- 
Douglas in MN
95.5 Audi S//6 Avant
73 BMW R60/5 mit Toaster Tank