Brake Pedal Hissing

[Kashew]

I have a a3 tdi yr 2000, recently when driving i can hear a hissing noise from the brake pedal, the only only way to stop the noise is to press the brake pedal. Has anyone experianced a problem like this or know what the cause is and how serious it is??

Thanks

[a8 tech]

Yes there was and is a recall for split servo pipe, please check with your local dealer if the campaign has been carried out or outstanding asap

[Kashew]

Hi, thanks for the info, is there a way i can check myself to see if the servo pipe is split?

[Crasher]

That won’t be a split servo feed hose, the hiss all the time but find the vacuum pump on the back of the head and run your hand along the plastic pipe and feel for splits at joins. If you do this with the engine running, take care not to burn yourself. To me It sounds like a faulty servo, a major leak from the servo can also cause turbo power delivery issues as the vacuum system also controls the turbo and EGR.

[Kashew]

Thanks for the advice, is a faulty servo a big job? is it ok to use a local mechanic or leave it with audi and should i expect a big bill???

[Crasher]

The worst part is bleeding the brakes, you need a diagnostic computer, a battery charger, two people and a pressure brake bleeder to ensure all the air is out. Otherwise you will have a long pedal travel that will initially be blamed on the master cylinder but after the MC has been changed eight times, the mechanic will finally realise something is wrong.

[a8 tech]

lol

[Crasher]

How many times have you seen that then? :D Me, many times..

[a8 tech]

o yes and it becomes a mind game, The pedal drops to the floor.
Best method I found years ago
FOOT POWER OVER PRESSURE BLEEDER, PUMP IT HOLD IT OPEN THEN CLOSE, PUMP IT PUMP IT PUMP IT,OPEN CLOSE ETC LOL

[Crasher]

I also do the foot pedal method whilst running the pump in outputs tests, seems to get a better result.

[a8 tech]

I avoid the basic setting and bleed conventionally which 9/10 gets the pedal spot on.