The braking system of a vehicle has one important purpose; to slow down (and stop) your vehicle. The brake pedal is what you use to communicate to the car that you want it to slow down and it should always function the same.
When you push down on the brake pedal a little, you’re telling your car to slow down a bit. When you apply maximum force to the brake pedal, you’re telling your car you want to slow down as fast as possible. But even with stomping on the brake pedal, it should not go all the way down to the floor easily.
So what happens if you push down on the brake pedal and it does goes all the way to the floor with very little effort? If the pedal sinks to the floor, there is an issue in your braking system that should be addressed as soon as possible. The inability to stop quickly is very likely to cause a serious accident.
Reasons Your Brake Pedal Goes to the Floor
Technically, there are three main causes that would make the brake pedal sink all the way to the floor.
1) Leak from Brake Line or Brake Caliper
One of the reasons is, the brake system loses pressure from an external brake fluid leak. The leak may coming from a brake line or one of the brake calipers on your vehicle. Finding and fixing this leak should be your top priority.
2) Bad (or Leaking) Master Cylinder
Another reason is a bad brake master cylinder allowing fluid to bypass seals internally. This master cylinder is where the action of increasing the brake fluid pressure occurs. If this cylinder is not working properly, there are two possibilities: the brake system won’t be as powerful as it usually is or the brakes won’t work at all.
3) Air in Lines
Unlike brake fluid, air is compressible. This means it will be much harder to get a proper, consistent braking feel when you have air in the brake lines.
If you’re low on brake fluid, top it off and then bleed the lines to be safe. If you have no brake fluid, there is a very good chance you will not be able to stop until you hit something.
4) Brake Fade
Typically only an issue on hills or after repeated heavy braking, brake fade is a reduction in stopping power as the braking system takes on more heat than it is designed to handle. If your pedal starts to sink after heavy braking, you may have boiled your brake fluid, or perhaps your brake pads are hotter than they were designed for.
When your brakes fade to the point where you can barely stop, you should replace your brake fluid. Once your brake fluid boils, it is never able to handle the same amount of heat as it once could.
Diagnosing and Fixing the Problem
The good thing about noticing when the brake pedal goes down to the floor is that it’s usually very easy to diagnose, as there aren’t many possibilities as to why it’s happening.
Even better is that you can actually diagnose the issue yourself even with limited mechanical experience. In case the brake pedal goes to the floor, there are several actions to be taken in order to fix the issue.
1) Check Brake Lines and Brake Calipers (or Wheel Cylinders)
The first action you can take is to check the level of the brake fluid. If the fluid is full, it means that there is no leak. If some fluid is missing or it is empty, it means that you have a leak somewhere.
In case there is a leak, you must check all brake lines from all four wheels, to see if the brake lines are leaking. In case the brake lines are dry, it means that the issue is not there. If you see that there is a leak on one of the four wheels, it means you found the issue.
In order to fix it, you need to remove the wheel, find the source of the leak, and replace the part if necessary. Often the culprit is a leaking caliper or wheel cylinder seal.
2) Check the Brake Master Cylinder
The second action you can take is to check the brake master cylinder, as it has two sets of seals which can wear in time and cause leaks. If this is indeed the issue, the brake master cylinder must be replaced with a new one.
Pay attention, it is recommended to be replaced with a brand new unit, not with a rebuilt one because they don’t last long or sometimes don’t even work from the beginning. As with many other objects, when a second-hand unit is used, it is not as effective as a brand new one.
It is very important to mention that if you notice there are leaking signs, do not try to drive your vehicle, as the brake system will not work properly and is unsafe. Instead, try to fix the issue and if you cannot manage it by yourself, have your vehicle transported to the nearest trusted service, where trusted professionals are able to solve your issue.
3) Check Brake Rotors
Brake rotors are usually visible without removing the wheels and may tell a story about what’s going on with the brakes. Are there any gouges in the rotors? Do you see an uneven distribution of brake pad material along the surface of the rotor? Do you see any fluid leaks in the vicinity of the wheel?
4) Bleed Brakes
If you have soft brakes, you’ll want to try bleeding your brakes to see if this fixes the problem. Air in the lines can quickly lead to a squishy brake pedal.
Take care not to get air into the ABS module. ABS lines can be tricky to bleed.
5) Replace Your Brake Pads
If you’ve just experienced brake fade after a large hill or a track day, consider replacing your brake pads. Brake pads that are designed to handle a higher temperature may be more appropriate for your use case.
Keep in mind there is no one brake pad that can do it all. Changing to a sport pad may reduce your stopping power on the street during a panic stop, when brakes tend to be much colder than they would be on a steep hill under heavy braking.
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27 thoughts on “Why Does My Brake Pedal Go to the Floor? (Causes and Fixes)”
Have a ford escape that the brake pedal went to the floor one time and then would slowly go to the floor for a few stops after that. However, since then it has worked fine. Any ideas?
Have you tried bleeding the brakes?
I bled the master cylinder with brake pedal using little pastic screw in things with clear pastic tubes. then i pluged each of the 4 holes in master cyl with the little plastic screw in things but with screws in them to make them stoppers and i went into car and stepped on brake pedal. it was hard as a rock. i then attached the brake lines, bled the lines and brake pedal still went to the floor. I bled the master cyl on my vise until no bubles in the clear plastic tubes. put back master cylinder. i bled each line many times, no air squirted out, used 1/2 quart of brake fluid. Still pedal goes to the floor. ????? no leaks , brake fluid in resevoir stays at same level.
Someone else on a repair site said he put a piece of wood behind the brake pads so that the pedal would not have to go down as far. But I thought it would fall out so i found some old brake pads for my maxima and placed them behind the good brake pads. This would probably only help if your slider pins weren’t working well and left a space between rotor and pads or piston and back of pads after applying brakes. But brakes still go to floor.
That sounds like a bad idea. If your brake pads are worn, just replace the brake pads. If your pedal sinks to the floor, check the system to make sure there’s no air in the brake lines.
master cylinder is as hard as a rock when plugs in holes for each brke line, booster good, put double brake pads in calipers to leave no space for brake fluid to be used up, bled all lines many times and got no air to come out. Still brake pedal goes to the floor. please help, $100 to he who solves my problem.
What do you mean by “put double brake pads in calipers to leave no space for brake fluid to be used up”?
I have a 66 Cadillac and the brake pedal goes down about 3/4, I had it to two different shops and they tell me its normal, I just don’t think that’s right.
Some brake pedals require more force than others. That said, if you think your brakes feel spongy it may be a good idea to have the brake system bled. Replace the brake fluid while you’re in there if it’s been a while.
I have a 2000 buick park avenue ultra supercharged. Cars solid rust underneath. I had to replace brake pads on front and all four bleeder screws just dissinigrated at the touch of a wrench so I replaced front two calipers so if have somewhere to bleed from but now I can get my breaks to bleed with the engine off and as soon as I start it I’m back at the floor. Theres a brake distributioning system referred to as the brake proportioning valve and I think it may have rust or other contaminants inside of said valve cause I could get my front passenger side to bleed buy couldn’t get any kind of bleed off my driver side caliper(both new) so I replaced that line and then still couldn’t get it right. So my question is is there a way that I could bypass this proportioning valve for the time being as though I can’t afford it right now by running Lines straight from the master to the calipers? And if so would I have to bleed both sides at the same time in order a assure that the air wouldn’t be just going back to the other side everytime I let off on my bleeder screw?
Have you replaced all four bleeder screws and/or calipers? It sounds like the system isn’t sealed, and each time you try to bleed one corner perhaps it’s pulling air from somewhere else. I’m not sure if you can bypass the proportioning valve.
Since the car is very rusty I’m wondering if there is a leak elsewhere in the system that is allowing air in while you’re trying to bleed the brakes.
My brake pedal goes to the floor without any resistance in the morning but stays firm and responsive to the touch for the rest of the day as soon as the pressure has built up again.
I would get it checked out. Bad brakes aren’t something to mess around with.
I have a 2006 Dodge grand caravan… My breaks go all the way to the floor and has started this a while ago… I have changed the brake pads, calipers, master cylinder, brake booster, and still can’t figure it out…
I have an s10 ZR2 2002 4 wheel drive with abs all around. I blew a back break line and drove it home just using the front brakes to stop. Replaced the bad line and then attempted to bleed
all four wheels according to proper procedure, but was now unable to get any pressure on the brake pedal, it just keeps going to the floor, no resistance. Only dribble coming out of all four calipers when bleeding them. Replaced the master cylinder and two front calipers because of age, still the same problem. With a vacuum gauge I was able to see a reading of 17 in the brake booster which held for 4 hours until I pressed the brake pedal. The abs fuses are good, anyone have an idea what is causing my loss of brakes?
Double check that all four bleeder screws are tight. Some vehicles also have a bleeder screw on the master cylinder, so look there as well.
When you pump the pedal several times, does pressure return? Do you see any brake fluid leaks around the vehicle? Does the fluid level in the reservoir drop?
should read “stomping on the brake pedal” (not gas)…
the advice about buying a new (simple system) master cyl. rather than rebuilt is sound, however NOT because remanufactured components in general are of poor quality…a rebuilt master cyl. can often be found at very low cost, and is preferred by shops that just want to get you going on the cheap
Thanks for catching that. I’ve updated the article.
In my experience remanufactured parts are hit and miss – they can anywhere from excellent quality to defective out of the box. When they work, they’re definitely a great way to get you going on the cheap, like you said.
The difference in used is if that is your choice buy a seal kit and a hone kit to fit the cylinder bore of the master cylinder. Tear down the defective master and inspect the cylinder bore for pits or deep scratches, if so buy a new master. If smooth very lightly ( it’s aluminum be gentle ) hone the cylinder bore with a 3/8 drill so it has a light cross hatching then STOP! Lube the seals before install with brake fluid or some kits have a paste to use. Be gentle on the seal install, no hammer mind set here. Once together prime the master with brake fluid by moving the plunger in and out till fluid comes out of the master. Install master and bleed all four wheels starting with the shortest line (front wheel closest to the master) and the next closest wheel till all are bled of old fluid and air pockets. Test brakes on back road. The pedal should be hard by mid travel or before. That said a new master of good quality will possibly last longer but a good rebuild will last several years at least. Short on money? Try this if you have the tools and skill. Otherwise buy a new master and prime it before installing.
i have a BMWx5 brack peddle went hard and brake lock on took it to a garage they changed the servo and it was still the same then they change the master cilinder and bleed it i fech it back and drove down the road and lost peddle completely but there was no leeks on the brakes abs unit is working fine
I’d take it back to that garage to see what happened.
Most likely the master was not bled properly. You need to get the car repair company to go back and fix it.
brake pedal only goes to the floor when engine is running
With engine not running pedal returns to normal
any suggestions to problem
Some cars have a power assist unit in back of the master brake unit on the firewall of the engine compartment. It may not be functional due to a leak in the diaphragm.
Hi Joe, if the diaphram is leaking would the pedal by spongy or hard ?? 1977 k5 blazer.try
A B S light on all the time. 2004 f150
Could be a bad wheel speed sensor or the ABS module. I’d take it to a shop to get it checked out.