2007 s3 hissing from brake pedal?

[AndrewBates]

Hi new to the forum and had a quick search about an issue im having but couldnt find much, recently got a 2007 s3 in sprint blue a few days ago, love the car but having an issue with a hissing noise that happens constantly but dissapears when the brake pedal is depressed and comes back when it is released, any info or help would be appreciated

 

[max69vk]

Its a common fault (especially on MK5 Golfs) due to a worn seal/valve on the brake booster unit. Typically VAG are well aware of the fault but wont admit any liability as to fix the 0.50p part the entire brake booster unit needs to be replaced, which in turn usually requires the engine to be unbolted and rocked forward (for clearance). Rather strangely this seems to affect more Auto or DSG equipped cars with cruise control rather than Manual gearbox vehicles.

Some people have driven with this fault for years/months without any other issues or it affecting the brake performance, the choice is yours as to whether you want to take the risk.

 

[AndrewBates]

I'm a mechanic myself(final year apprentice) so would happily do it myself, by brake booster do you mean the servo/master cylinder unit? Is it always that that's the fault or can it be traced to a vacuum pipe or anything?, Thanks for the reply