Ive got a 2000 Z3 owned it for many years, manual 2.5 roadster with dsc. My zed wasnt driven for several months due to work schedule, pulled it out of the garage and the brake pedal went to the floor when braking, heard a woosh of air under the dash when i press the brake pedal. I checked all 4 rotors/lines and no leakage, ordered a new master cylinder installed this afternoon but same issue, a sound of hissing air under the dash as i press the brake pedal down. Any ideas of what might need to be replaced?

 

thanks in advance for any suggestions.

Hi Mike....welcome to the Forum

It sounds very much like it is the brake servo that has failed and the mechanical linkage interaction is no longer present and as a result leading to lack of pedal and also would explain the hissing air noise.

I would remove it and examine it to see whether this is the case.
Also worth checking that the vacuum hose is attached and not ruptured.

 

 

Thanks for the reply, ill give it a look this weekend. Hopefully that will solve the issue...

There is a brake vacuum line that runs from the servo unit check that at the point it meets the servo is a seal and a non return valve if the seal goes or the non return fails it will give those symptoms.

Dave