Loud hissing sound from break pedal....
 

My son went out to start my jeep (1999 jeep grand cherokee this morning and pressed the break. He pressed it so hard that I now have a loud hissing sound from my break pedal. Has this ever happened to anyone or do you have any idea what it could be?

Thanks!

Diaphragm in brake booster has a hole in it maybe, get a new brake booster.

Gonna be around a hundred bucks, labor not included.

Kid may have future as NFL kicker.

I agree. Mine has the same thing only when you press the brake hard. I'm putting the job off until spring.