Re: 98 mustang brake problem
I don't think it is wise for a novice to try and fix brakes. If the pedal is going to the floor then it sounds quite dangerous and you should take it to a mechanic. In fact it should be returned to the place that repaired your brakes before as it seems like it is a problem with the work they carried out especially if they have worked on the master cylinder already.
It sounds to me like there is a problem with your Master cylinder if the fluid level is still full and the pedal is going to the floor.
The hissing sound will be the brake booster as this is operated by vacum.
71 429SCJ Mustang