No brakes and air hissing into the cabin?

[SavageMotorsport]

Hey guys, I have a 2004 Jetta Wagon 1.8T and I am having a problems with the brake booster leaking air into the cabin. On the boost gauge it is sitting at -15 and has a small hiss the the whole time. If you press the pedal all the way down the hissing sound goes away and the boost gauge moves down to -20 where it belongs....

The car has hardly no brakes at all.You have to keep pumping the brakes to make the car slowly come to a stop.

I removed the OEM booster with a salvage yard booster and it does the exact same thing. Tired of this issue I went and ordered a new booster from the dealer. I installed the brand new booster and and even replaced the o-ring on the back of the master cylinder and I still have the same problem...

I pulled the hose off the intake and you can't blow through the check valve either....



Anyboddy have a solution???? I am puzzled big time!!!

[VWBugman00]

Have you checked the hose itself? I had the vacuum source come loose on me once, and it made that sound. If you replaced the booster, and it's still making that noise, I doubt its the booster. Try replacing the hose and the check valve, see if that fixes the issue.

[Jetazg03]

i am having a similar problem with my 01 golf. No brakes at all & when depressing brake pedal I can hear a hissing or air sound coming into cabin.
I personally think the Master Cylinder has failed...I am going to start there. Let me know what you find. Look at the Master Cylinder!
How much was a factory Booster anyways?

[VWBugman00]

For the brake booster, about $200 from ECS tuning, for the master cylinder itself, $140 ish from ECS

[Holmes741]

Gotta find where that hiss is coming from....Have any friends that smoke? Blow smoke into where you think the hiss is coming from and see if you can locate it. I know it sounds old school, but it really can work...