Soft VW Passat brakes

[Louis-Alain Richard]

> 
> I'd be taking a hard look at the ABS valve assembly. 
> 
> Roy Wendell


I agree with Roy. The ABS/TCS/ESP unit is basically a valve block with 8
or 12 electro-valves in addition to a few small reservoirs. The brake
pressure passes through it all the time. And there is a special
procedure to bleed it, usually it involves running the pump with the
"escape" valves open. To do it, one must use a device like VAG1552 or
similar. So if your dealer didn't complete this operation, there still
can be air in the block no matter how thorough they were with the
standard bleeding operation. However, I'd be deceived by such a dealer,
because it's a standard procedure for cars with Bosch 5.3 or 8.0 ABS
units. In fact, with a spongy pedal and no hydraulic components faulty,
the ABS unit is the one to be replaced.

There is another possibility: if your car has a vacuum power brake
system, a faulty vacuum booster can produce too much assist and then
help push the pedal to the floor with little pedal pressure. It's a
common failure mode on the newer car with the "Emergency brake assist",
the mechanical or electronic device that makes the vacuum booster to
pushes the pedal to the floor in an emergency stop. 

HTH, and good luck !

Louis-Alain