Brake Bleeding Problem.

[passat TS]

David,

Thanks for replying.

I did not do a bench bleed per say( btw, the bentley doesn't mention it, it 
just says in MC replacement; "...bleed the brakes...").
What I did was open the fittings in the MC while at 15 psi, and let some 
fluid running.
You might be right regarding the angle, and with the longer MC, this angle 
is even worst.

The problem doing the bench bleed is the two of the ports on the MC are 
pointing directly down, so when I remove the provisory bleeding lines, the 
fluid in the MC will drip away leaving air inside.

I'll try the bench bleed anyway.

Hopeful, there is a chamber inside the MC that is trapping this air, which 
won't leak the fluid while I transfer from the bench lines to the  actual 
brake lines.

Thanks,

Carlos.



>From: David Conner <conner at cfm.ohio-state.edu>
>To: passat_ts at hotmail.com
>CC: quattro at audifans.com
>Subject: Brake Bleeding Problem.
>Date: Fri, 27 Jul 2001 10:39:08 -0400
>
>You wrote...
>"I need some help diagnosing this brake bleeding problem.
>
>I replaced literally all the brake system in my CGT, (incl MC)...
>So, I jumped in the car and the pedal is going all to way to the floor, 
>with
>little or no resistance.
>
>Air trapped in the MC?"
>
>Carlos,
>My guess is air in MC.
>The following tip is copied from
>http://www.cardone.com/english/club/
>
>"It is recommended that you bench bleed the MC before installation.
>  All air must be removed from the master cylinder using the bench bleed
>method.
>Failure to do so is the #1 cause of failure and may result in spongy or low
>brake pedal; this will void the warranty.
>  Use a wooden dowel or blunt tool
>Use only a dowel or blunt tool during bench bleeding.
>Sharp or metal tools can cause damage to the master cylinder piston and
>bore. "
>
>So what is this bench bleed kit?
>Essentially ... you clamp the MC in a vise.  Run lines/hoses from the brake
>line outlets back into the reservoir.  fill reservoir with fluid, then pump
>the piston by hand with a wooden dowel.  This will circulate the fluid thru
>the piston and back into the reservoir.  Do this until no more air is seen
>in the tubes.  To fabricate these return lines you need to get some of the
>old lines, cut them off short, and screw the short pieces into the MC
>outlets.  Then route clear plastic tubing from the lines into the
>reservoir.  Luckily you have some old lines laying around from the
>replacement job.
>
>HTH,
>Dave C.
>
>I think this bench bleed method is especially important on cars where the
>MC is installed at an uphill angle which can trap air in the upper portion
>of the MC.
>
>
>


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