Soft VW Passat brakes

[E. Roy Wendell IV]

On 9/19/06, Peter Orban <peter at peter237.imti.nrc.ca> wrote:
>
> Hello Everyone,
>
> I have a '03 Passat, V6, with 5-spd fwd transmission, with some brake
> problems.
>
> I know it is not stricktly an Audi, but under the skin it is and Audi
> design
> ;-)
> I also did check this on the VW Vortex and Club B5 tech forums  
> before, no
> real
> help there.
>
> In any event, the problem is when the engine is running, I can push  
> the
> brake
> to the floor without too much effort. When last year I took ther  
> car for
> brake
> fluid replacement I mentioned this to the dealer. They declared the  
> car
> "unsafe
> to drive" and butchered their way through an MC replacement (don't  
> even
> ask!).
> After that the brake has been exactly as before. When asked them about
> this,
> all they said that every V6 Passat does that. They also promised to  
> check
> with
> some VW tech people, but they never returned with any answer.
> I am taking in the car for a fuel pump recall (different dealer  
> though)
> and
> will raise this issue again, as I will be running out of guarantie  
> soon.
>
> Any comment on this as to the source of the problem?
> The car only has only about 16,000km on it.
> I am also wondering if anyone had similar issues with A6 and A4  
> cars, they
> probably have the same brake components?
>
> Thanks, Peter
> '83 4k

I'd be taking a hard look at the ABS valve assembly. Other than the  
master cylinder, this is the only component that could cause a drop  
in system pressure and therefore a change in pedal height with  
constant applied force without a massive loss of fluid. No experience  
with the particular model in question but the basic hydraulic guts of  
ABS systems haven't changed in quite a while and the type 44 manuals  
have extensive test routines for the exact problem you describe. They  
involve plumbing a very high pressure gauge into the brake lines,  
depressing the pedal, and looking for any signs of pressure drop over  
a specified time period.

Roy Wendell
erwendell at mac.com
Too many type 44 tq
A pair of MR2s