Hi chaps, just purchased an 2008 Mondeo 2.0tdci Titanium X. Its a great car but I have notice a quite loud hissing / Vacuum noise from the drivers side of the dash. Its not a high pitch hiss and its continuous until you stop (no volume changes)I think I can faintly hear it at a stand still

I turned off the all ventilation (opened and Closed vents) but no change, turned off the radio also.

Any ideas what this could be? Thanks in advance

astonm

Could it be the air con pipes ?

[quote name='Mondeoman' timestamp='1305839581' post='128083']
Could it be the air con pipes ?
[/quote]

Could be but I did have it turned off, the other way I thought of it is that it could be mixed up with a Vacuum noise?? Maybe that would change the diagnosis?

UPDATE: Well the hissing / vacuum noise is coming from behind the drivers side of the dash. It is a constant noise UNTIL that is you put your foot on the break!!!! When stationary you can hear the noise put your foot on break it goes completly.

Any ideas??

sounds like a seal on the brake servo has worn allowing air to bypass

Is that a big job?