"Hisssss" noise form the brake
 

I noticed a low "hissss" noise from the brake when the car (99 S80T6) is running. It sounds like a small leak from a vacuum hose. This noise stops as soon as I step on the brake pad and resumes as soon as I release the brake pad. I checked the brake fluid level. It is OK. The brake is working well.

Tried to contact my mechanic, but it was after 6pm and he was closed. Any idea what was the problem? Thanks.

RE: "Hisssss" noise form the brake
 

Sounds like a bad brake booster to me. Pretty common problem.

RE: "Hisssss" noise form the brake
 

Hello Tech

Thanks for your prompt reply. Is it still save to drive it for a few more days. I'm pretty tied up until next Tuesday. How many hours will it take to replace it? Thanks.

RE: "Hisssss" noise form the brake
 

You should be safe with it like that. Also it should take a couple of hours to either get is swapped or for you to swap it.

RE: "Hisssss" noise form the brake
 

Thanks a lot. Tech.

RE: "Hisssss" noise form the brake
 

i just bought a 01 s80 and i have the same hissing problem i see that it is a very common problem obviously if it is stickied but how safe is it to drive under this condition? I just dont want to mess up my new beloved car.

RE: "Hisssss" noise form the brake
 

As long as the brakes still feel pretty good you should be fine for a little bit. If the pedal gets hard then change out asap.

RE: "Hisssss" noise form the brake
 

i have a two week 2001 S80 2.9 with stc and my brakes hiss so i have come to the conclusion that it is brake booster since it seems to be a common problem so here is my question where i can find a new one for cheap volvo and fisher tires told me that its 700 for the booster and fishers said 620 so where did you find yours and hopefully for cheap. The labor was 260 is that okay for that type of service? THanks for the help in advance.

TO TECH
how long is a lil bit the breaks are nice soft and responsive at the moment

RE: "Hisssss" noise form the brake
 

It might be a day or a year you never know. If the pedal gets hard it is time to replace ASAP.