Brake problems

[flat-planedCrank]

Hi all,

Got some problems with the brakes on an audi a4...

They seem to seeze on when the ambient temp gets low. Even if the brakes seem ok when you move the car, as soon as you touch the brake pedal the pedal goes to the floor and the brakes stay on.

Garages have looked at it and said they can see nothing majorly wrong - they saw one caliper was sticking so it was replaced, also changed the brake fluid as a precaution - but the problem has returned.

Does anyone have any guesses as to where to look for the problem? Master cylinder? Servo?


Any help or thoughts appreciated

[XG332]

Master cylinder might be sticking hence not returning and staying on.

[davepoth]

Does the car have rubber brake flexible hoses?

I've heard of them decaying inside and acting like a one way valve - the fluid can get down to the caliper but can't get back. It would cause the problem you're having.

[littleredrooster]

Sounds like a servo problem to me.

[flat-planedCrank]

Thanks for the help all - local garage thinks its the master cylinder as well - but apparently the master cylinder + servo are one unit?

So it's an expensive job to replace - apparently the steering rack needs to come out

[saladdodger]

Must be a week for duff Audi brakes, mine are causing me grief as well, issues with bleeding,

What year is your A4

[flat-planedCrank]

2001, its an A4 B6 - http://en.wikipedia.org/wiki/Audi_a4#B6_.28Typ_8E....

[oakdale]

As has already been stated, it's usually the servo on these.