I've got a '99 Suburban 350 2wd. When brakes are applied, it sounds like air leaking out of an air hose. The noise is constant until you let off. My mechanic told me that I need to replace the brake power booster. Braking is limited even though I just replaced the front brakes. Can anything be done to improve the functioning of the booster or is a new unit the only solution?

 

If the booster is leaking air it must be replaced.

 

Thanks for your response,

Eric

 

Eric, just because you have a sound like air leaking out of your brake booster doesn't mean it is bad. The valve in there will make that sound sometimes.

To check and see if it is bad, turn your car off, pump the brakes fifteen times and hold pressure. Crank engine and if your foot goes down about an inch or two and stays there, the brake booster is good. If it goes straight to the floor or goes down and comes back up, then it is bad.

I wouldn't automatically assume that it is bad just because it is making a noise.

 

We're all just kind of assuming the hose from the Intake Manifold to the Booster isn't dry rotted, cracked, or has a hole in it.

That hissing noise could be air going either way.

 

The manifold hose is in good shape. I replaced the power booster for $113 (O'Reilly Auto Parts) and I'm back on the road. Decided to replace the master cylinder which was original equipment for another $30.