Hissing sound driver side near the brake booster.

[Xugos]

Recently a hissing sound has developed near my brake booster. When i press the brake it goes away, the moment i release the brake it comes back. The car stops fine although i feel that it may have a tad play before i feel pressure.

Normally i can figure things out but this one has me stumped, and i dont feel like breaking something or getting to far ahead of myself.

Thanks in advanced.

[mt.aero]

Check the vacuum lines going from the throttle body to the master cylinder and the one from the brake booster to MC too. Sounds like they are cracked or loose.

[Xugos]

believe i found the issue. I checked the vacum line from the master cylinder to the intake and the seal on the master cylinder is bad. if you or anyone may know the actually name of the part or a part number be very helpful but i will be making a trip to the dealer to pick the part up.

Edit: i think this is the part i need. eEuroparts - Brake Booster Grommet - # 4836680

[mt.aero]

I would say it looks like you got it figured out. Nice!

[Xugos]

Well it is still hissing but not as loud now. The new grommet went on tight so i cant imagine it is leaking still. what i need to do is just replace the vacum lines and see if that fixes it. anyone know how much line i need to buy, sizes, fittings etc. and maybe a diagram of the lines so i can put them on right.

I hope the booster isn't going bad i will be very upset. does the booster show signs of dieing in terms of stopping power?

some info on the car:
169k miles
9-5 aero 2003

[jlrSAAB]

the hissing sounds may be produced by air in the brake circuit.

vacuum the circuit in a brake specialist workshop and refill again.

this option is more simple and cheaper.

[Tamas Laszlo]

It will be the brake booster itself......membrane is broken inside and leaks. When the hole gets bigger even engine check light will come. It will produce a "poor fuel" in cylinder where the vacuum connected due to leak.
I think this could be your problem....
Check the booster with a special equipment in WS for leak.
Regards

[Tamas Laszlo]

anyway...
The after-market booster is quiet cheap. (thesaabsite.com)
So don't worry!!!