Brake problems

[Jaime J]

Air leakage from buster?

Yesterday while going home from work, I noticed that my brakes, when applied, were different, maybe sponge at low RPM’s. When I arrived at home and turned the engine off, wile applying pressure to the brake pedal, I heard an air sound coming from the pedal area. I don’t know if it was coming out or it was being sucked.

I have a1997, 1500 GMC Z71, 5.7 with 130,000 plus miles

Can anyone tell me if I have a problem with my Buster or if it’s the Master Cylinder?

Thank you in advance for the help. I am new to the forum.

[GM-Tech]

First of all, it's a booster, not a buster.

 

When you step on the pedal, air is drawn into the booster from inside the vehicle from the area where the rod comes out of the booster that connects to the brake pedal. This is normal.

 

However, this is usually not that loud and it only occurs AS you are pressing the pedal. Just a brief (1 second or less) hiss. It should not continue to hiss while you're holding the pedal down. If it does continue, you have a booster problem.

 

One test for a booster is, with the vehicle not running, pump the pedal 4 or 5 times to deplete the reserve in the booster. Let the pedal up, rest your foot lightly on the pedal and start the vehicle. The pedal should fall away, indicating the booster is operating. Understand that it could still operate even if there's a small leak.

 

A bad booster does not cause a spongy pedal. It causes a hard pedal.

[Jaime J]

Thank you very much for the help and sorry for misspelling the word I will follow your instructions and I will let you know the results.