Hello, Before I get into buying parts like crazy for no reason I would like to ask about this: Couple of days ago while driving downhill coming to a stop and waiting for traffic my brake pedal started to go down to the floor. replaced 2 rear wheel cylinder one was leaking bad 2 months ago.

Noticed as well that between the master cylinder and the power booster brake fluid leaking (picture below) the vacuum hose it's ok not broken or craked

My question: which one should be the problem causing the leak? master cylinder or power booster? and if this will be the cause for the pedal going to the floor.

Thanks !