I have a hissing sound coming from my brakes, inside near the pedal. One thing I can think of is the booster is making the sound and I hear it inside, sounds like a vacum leak. Is defintaly is the brakes, if I push on the brakes and hold them HARD the sound goes away, lift up it is loud then levels off.

I have yet to pull it into the garage to look at it. Brakes do work fine. Booster?

 

OK, pulled it into the garage today and took a look. The rubber boot had a tear in it. I put some silicone on it in hopes it will plug the vacum leak, but if it does not... Is this a servicable item or do I need a whole new booster?

 

The silicone worked, no more hissing, but it is just a patch, I am sure it will happen again. So my original question applies....

Is this rubber boot servicable or does the entire booster need replaced?