Master Cylinder internal seals are failing. Replace the Master Cylinder before you have an accident when it fails permanently.
you either need a new brake master cylinder or your brakes need to be bled
Have your brake system checked immediately! (by a proffesional)
Try bleeding your brakes. If there is air in the system it can give a spongy feeling to your brake pedal and require you to pump your brakes and/or put your brake pedal to the floor.
Check your brake fluid. Next maybe your brake lines need to be bled. OR you just might need new brakes.
You need to bleed the brakes.
i do not no
The power brakes on most vehicles operate on the engine vacuum. If there is a leak or problems with the power brakes it can make a hissing sound. But then, sometimes power brakes do that when they're working properly. It could be from either a hole in the diaphragm of the brake booster or normal operation. If the sound is new, and was not there before, and your brake pedal is going to the floor, then you should have the power booster replaced.
Air in the brake system- Brake system needs to be bleed and fluid needs to be added while you are doing that.
If you are losing fluid and the pedal is low, you have a brake fluid leak.
Probable causes: Low or no fluid in reservoir; Worn brake pads/shoes; Air in brake lines; Leaking brake line.
The best way to tell when you need brakes is by squeaking, when the brakes are rubbing against the metal, when your brake pedal goes all the way to the floor and when you are running out of break fluid.
try and bleed brakes , if that wont work you need a master cylander