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.

 

Never heard of brake fluid vaporizing. And the brake boosted is run with vacuum not pressure. But either way you need to see where it is leaking from and then go from there.

 

It's spraying out from somewhere beneath the booster. I can't see from where exactly without taking things off. I'll try that next. It's definitely not leaking from the master, or the connection between the master and booster. I don't think it's coming from a brake line either, because of the hissing, but a spray of brake fluid goes all over and it's hard to know for sure.

 

Yep, sounds like you need to clean that entire area with brake clean and make sure everything is dry and then start looking. Probably a job that would be easier with someone helping. Make sure to wear safety goggles so you do not get brake clean or brake fluid in your eyes.