I noticed that there is a hiss when I step on the brake. This Voyager has power brakes. There does not seem to be any noise until I step lightly on the break pedal. When I push really hard and the pedal goes down a bit more the hiss stops.
The brakes work fine.
What is causing this noise? I assume it a vacuum or leak in the booster system (since the booster is exposed to air pressure on one "side". Should I replace the booster (assuming a catastrophic failure is coming) or is there something else that can be done?