Spongy brakes

Tiny
KINGW1701
  • MEMBER
  • 2011 LEXUS GX 460
  • 4.6L
  • V8
  • 4WD
  • AUTOMATIC
  • 100,000 MILES
Brakes are really spongy. Can hear a hissing noise with I press on brakes. Sometimes at a stop the car will release but a tiny bit and I have to press on brake pedal harder to stop vehicle. Pedal also has a lot of travel in it. Brakes were replaced at approximately 80,000 miles. Took to a firestone complete auto care center they said nothing wrong. Another shop said it is a possible brake booster/master cylinder but could also need bleeding.
Thursday, May 5th, 2022 AT 7:48 AM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

If the brake system hasn't been touched since the pad replacement and this started now, there isn't air in the system unless a line has failed. You would likely see a leak if that was the case.

I need you to try something. With the engine running and the vehicle stopped, pump the brake pedal a few times and then hold downward pressure. See if the brake pedal slowly goes to the floor. You can do this with the engine off, but the pedal will be harder to press.

Also, let me know if when stopping the pedal is stiff and hard to press.

Also, open the hood and have a helper start the engine and depress the brake pedal while you listen to see if there is a vacuum leak at or around the brake booster. The brake booster is located behind the brake master cylinder. I attached a pic and circled the master cylinder to help you locate the booster.

Let me know what you find.

Joe

See pic below.
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Thursday, May 5th, 2022 AT 9:01 PM
Tiny
KINGW1701
  • MEMBER
  • 3 POSTS
Thank you for the reply! I've owned the car since it had 85k miles on it and it has done this from day 1. I can hear hissing when I pump the brakes and the pedal never really stiffens up. It's like when I stopped at a light, I can feel the pedal give just slightly then I have to push it further to stop the car from rolling.
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Friday, May 6th, 2022 AT 12:02 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

If you are at a stoplight holding the brake, will it eventually go to the floor? Also, is there anything that changes the hissing sound you mentioned? For example, does it get louder if you press harder?

Let me know.

Joe
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Friday, May 6th, 2022 AT 7:56 PM

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