# Hissing noise by the brake booster **URL:** \ **Category:** General Discussion\ **Tags:** fx35\ **Created:** [March 3, 2019, 11:01am UTC](https://community.cartalk.com/t/hissing-noise-by-the-brake-booster/135673 "2019-03-03T11:01:15Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![bentham72\_148947](https://avatars.discourse-cdn.com/v4/letter/b/9d8465/32.png) [@bentham72\_148947](https://community.cartalk.com/u/bentham72_148947)\ **Post date:** [March 3, 2019, 11:01am UTC](https://community.cartalk.com/t/hissing-noise-by-the-brake-booster/135673/1 "2019-03-03T11:01:15Z")
I am hear a hissing noise by the compartment where the brake fluid is located. Could this noise be caused by have bad brake pads that need to change. ---
**Author:** ![tcmichnorth](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tcmichnorth/32/25126_2.png) [@tcmichnorth](https://community.cartalk.com/u/tcmichnorth)\ **Post date:** [March 3, 2019, 11:46am UTC](https://community.cartalk.com/t/hissing-noise-by-the-brake-booster/135673/2 "2019-03-03T11:46:40Z")
There is a large amount of vacuum stored in your brake booster. Start your car and let it idle for about 30 seconds. Push your brake pedal down. It should depress fairly easily for about 1/3 to 1/2 way down. Let it idle for another 30 seconds and do not touch brake pedal. Turn the car off, and wait a couple of hours. After a couple of hours get in car. Do not start it and press on the brake pedal. It should go down easily for the first 1/3 to 1/2 way down. It should do this 3 times then you will notice that it is hard to press down from the top. If it’s hard to press down from the top the first or second time, you have a leaking vacuum hose between your engine and brake booster or a bad brake booster. ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [March 3, 2019, 3:15pm UTC](https://community.cartalk.com/t/hissing-noise-by-the-brake-booster/135673/3 "2019-03-03T15:15:43Z")
> [@bentham72\_148947](#): > > Could this noise be caused by have bad brake pads that need to change. Very doubtful , but it does not really matter . You have a problem that could cause failure at the worst possible time . Find an independent brake shop soon. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [March 5, 2019, 4:29am UTC](https://community.cartalk.com/t/hissing-noise-by-the-brake-booster/135673/4 "2019-03-05T04:29:35Z")
Unlikely related to brake pads, but good chance as posted above there’s a problem with the brake power booster. Besides braking problems, this could cause engine-performance and emissions problems too, so good idea to get it looked at by a shop w/due speed. ---
**Author:** ![bentham72\_148947](https://avatars.discourse-cdn.com/v4/letter/b/9d8465/32.png) [@bentham72\_148947](https://community.cartalk.com/u/bentham72_148947)\ **Post date:** [March 12, 2019, 1:47pm UTC](https://community.cartalk.com/t/hissing-noise-by-the-brake-booster/135673/5 "2019-03-12T13:47:31Z")
I tried and it did not work. It is also draining my battery. ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [March 12, 2019, 1:55pm UTC](https://community.cartalk.com/t/hissing-noise-by-the-brake-booster/135673/6 "2019-03-12T13:55:41Z")
Your first post was 9 days ago . Brakes are kinda important so why do you not have this in a shop. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [March 13, 2019, 3:05am UTC](https://community.cartalk.com/t/hissing-noise-by-the-brake-booster/135673/7 "2019-03-13T03:05:21Z")
> [@bentham72\_148947](#): > > I tried and it did not work. It is also draining my battery. Check to see if the brake lights at the rear of the vehicle are on.