Why would the master brake cylinder make a thrushing noise and no brakes on a 95 Pontiac sunbird and?

Answer 1

There may be air in the brake system. Bleed the brakes and see if this helps. Bleeding the brakes requires two people, a quantity of new brake fluid, and wrench the correct size to open bleed valves on brake plates. The brake plate is the flat plate that the brake mechanisim is mounted on, and has a hose coming to it from the body of the car. The hose carries the pressure from the master cylinder to the individual wheel cylinders, and where it connects to the brake plate there is usually a bleed valve, which is a hexagonal piece of metal with a hole in it. When the bleed valve is loosened, it allows brake fluid to drain from the system. If no one is in the car with their foot pushing the brake pedal to the floor, air will enter the brake system through the bleed valve. So, have someone in the car who can push the brake pedal down, open the hood, and remove the cover from the brake fluid reservoir on top of the master cylinder. Have the brake pedal pushed down slowly (to keep the brake fluid from splashing all over the place. Be careful, brake fluid is highly corrosive!) as the bleed valve is opened, and held down until the bleed valve is closed. Repeat this procedeure three times, and then check the fluid level in the reservoir. Add fluid if necessary and go to the next wheel, which should be the left rear, as you want to start with the right rear, seeing as it is the furthest from the master cylinder. Work the right front after the left rear, and the left front last.