Hissing noise from brakes

Hi all, this morning for the first time ever I heard a hissing noise when I hit the brakes hard. They work for stopping me in regular traffic, pedal is not mushy. Has me concerned that something may be about ready to give out. I don't hear it all the time while driving, just if I'm on the brakes pretty hard. Original owner and never heard this before. Should I go ahead and bring it in to mechanic? Thanks!

 

Hi Sherry, you mentioned before that you worked at a dealership. Wouldn't one of your pals there take a look? It's probably just brake pad squealer indicating the pad is worn.

 

sounds like the vacuum booster is on its way out. With you foot on the brake shut the motor off, if the brake pedal immediately rises, the booster or check valve is bad. If it doesn't rise immediately see how many brake applications you can get with the motor off before the pedal get rock hard... usually 2 - 1/2 is OK.

 

Yeah, work at a Chevy dealership. As long as it isn't the motor the guys here can usually fix whatever is wrong. One of the guys changed my plugs for a 12 pack of Miller Lite I'll have to check out the pedal in a little while. Thanks!

 

With my foot on the pedal, turned off motor, it does't rise immediately. Not quite 2 pushes on the pedal and it is rock hard...1 push and just a little more and it won't move anymore.

 

Could be your brake booster. Brake fluid level good?

 

Will have to check the fluid after work. One other thing, it sounds weird but whatever is wrong seems to be messing with the idle, seems to be a bit smoother when I hit the pedal and hear the hissing noise, when I let off the pedal it goes kinda rough. No CEL lights or anything coming on.

 

That sound a lot like a brake booster or some vacuum issue.

 

take some needle nose pliers and squeeze the hose from the intake manifold to the booster closed and see if the idle improves.

 

I had them check it out at work, gonna have it replaced

 

cool, whats "it"?

 

Booster, gonna order it tjis week