Have a 2002 Monte SS with 84K miles.

Yesterday, suddenly pedal went to the floor. Found leaking brake fluid all down the area under the master cyl. Also can hear a loud hiss when depressing the pedal, and a cloud of what must be vaporized brake fluid rises from under the booster. It must be vaporized, not just fluid hitting a hot surface, because the engine was off overnight.

I'm assuming this means the master has leaked into the booster? If so, I think both need to be replaced, is that right?

All comments appreciated.

 

Try a new master cylinder first. Doubtful they both failed at the same time.

 

I thought that if brake fluid leaked into the booster, it would fail pretty quickly.