You could have a clogged brake line, most likely one of the front rubber ones.
The Brake booster might not be working correctly. Run the engine for a few moments, then turn the key off. Once the engine dies, press the brake pedal a few times. You should hear a hissing noise each time you press the pedal. Then hold the pedal down and start the engine. The pedal should move and get softer. If none of this occurs, verify that the booster has a vacuum source. If the booster has a vacuum source, and still does not boost the pedal effort, the booster is more than likely bad. One other alternative would be a bad check valve. Simply remove the valve and blow into it. It should blow easily in one direction, and not at all in the other.
Your power brake booster may be defective. You may have a vacuum leak or the booster itself could need replacing.
No, a busted brake booster will not cause the brake pedal to go to the floor. It will however cause the brake pedal to be extremely hard to push. A defective master cylinder will cause what you describe. Replace the master cylinder and bleed the brakes. It can because it happened to me. The booster lost vaccum and the pedal went to the floor. Sorry, you are wrong. The only reason the pedal went to the floor was because the master cylinder failed. The brake booster only boosts the pressure on the master cylinder and allows you to not have to push so hard on the brake pedal. Cars of yesteryear did not even have a brake booster and they stopped just fine albeit you had to push the pedal allot harder than with power brakes. A failing brake booster will not cause your pedal to go to the floor although it might cause it to go lower than normal before the brakes apply. As long as the master cylinder is good you will still have brakes, but you will have to really push hard and might even have to pump them up in order for them to stop the car.
If you are losing fluid and the pedal is low, you have a brake fluid leak.
Vacuum brake booster is defective or the hose going to the booster is leaking.
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.
you either need a new brake master cylinder or your brakes need to be bled
Have your brake system checked immediately! (by a proffesional)
This one is easy. Brake booster diaphragm is ruptured, causing a massive vacuum leak, which will cause the engine to run poorly when the brakes are applied. A loss vacuum assist will make it difficult to stop the vehicle.
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.
it could be a lot of different factors such as master cylinder is leaking past seels, crack in a brake line, leaking wheels cyclinders or calipers, air in the brake system that will cause brake pedal to go to floor if it is hard and wont move could be a failed brake booster
Air in the brake system- Brake system needs to be bleed and fluid needs to be added while you are doing that.
Probable causes: Low or no fluid in reservoir; Worn brake pads/shoes; Air in brake lines; Leaking brake line.
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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.
More than likely, there is air in the brake line or a leak in the line. Go to a mechanic and have the brakes "bled". He'll know what you are talking about. It's fairly inexpensive to do. Bad brakes, bad master cylinder, broken brake line, low brake fluid.
try and bleed brakes , if that wont work you need a master cylander
Defective Master Cylinder or broken brake line. Replace the master cylinder and bleed the brakes.
you need to have some one in the car to pump the brakes till thay get hard. and win they do you crake the bleder open on the brake calaper.the brake will go to the floor then you titan the bleder. and repeat thia over till the brake flouid comes out and there is no more air in the line.
Vacuum booster is working--When vehicle off there is no vacuum assist (for power brakes) When vehicle is on vacuum is present Brake pedal going to floor is another problem--no fluid in master cylinder? Leak in system? Brakes not adjusted properly?
The best way to know when your automobile needs brakes is when they start squeaking, grinding against metal, leaking brake fluid and the pedal going to the floor.
Brake Pedal Goes to the Floor After BleedingAlthough there could be more than one reason, I suspect that even though you may have bled the brake system, AND the brake fluid reservoir is full, your brake bleeding was not successful, and you STILL HAVE AIR IN THE BRAKE LINES, or in the wheel brake slave cylinders.
After changing the brakes the first few times you press on the brake pedal it will go to the floor; that's because the calipers haven't been pushed back to position. Remember that you had to retract the calipers completely before you could put in the new brake pads. Sometimes it takes a few pumps before the calipers are back in position. Make certain that the brake fluid is all the way up, then bleed the brakes again, and watch that fluid level. If it goes low for just one pedal push then you'll suck air again and you'll have to start over. Just one bubble of air in the brakes will cause trouble.
If your brakes are new and the system has been bled, your next step is to see if you have a leak in any of your brake lines and also check your brake master cylinder to see if it's working or not.
Low brake fluid, drums/rotors in need of replacement, pads in need of replacement, air in the brake lines, worn master cylinder, brakes out of adjustment... all possible reasons.