Changed brake pads and no obvious fluid leaks, brake pedal goes to floor with no resistance.

Changed brake pads and no obvious leaks, pedal goes to floor with no resistance
Experienced mechanics share their insights in answering this question :
When you replace your brake pads you had to push back the caliper pistons to get the pads out and the new ones in. After the calipers are put back on you will have to pump the brake pedal several times to pump it up using short strokes.

If you pushed the pedal to the floor then you may have to pull the pedal back and then use short strokes until you get a hard pedal. This is normal. Now after you try pumping the brakes up and the pedal keeps going to the floor, then you either have a leak somewhere or the master cylinder has excessive debris inside it and caused the pistons to get damaged. You would need to replace the master cylinder. If you want to have this looked at in person before doing a repair, a certified technician from YourMechanic can come to your home or office to verify the cause of your braking issue first.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

The cup seals or the cylinder bore may be worn. Any time that the brake pedal of a vehicle is fading towards the floor, internal leaking or cup seals being bypassed must be considered. A fading pedal that has no external leak is one of the most common master cylinder symptoms caused by the cup seals.
A brake pedal that sinks all the way to the floor could indicate a problem with the brake master cylinder or it could be due to a brake fluid leak. In either case, a careful assessment is required – once the issue is accurately diagnosed, you can then go ahead and fix the issue.
But if you hear a hissing sound when pushing down or letting up on the brake pedal, it usually is caused by the brake booster leaking air, which could mean there`s a leak in the booster diaphragm, master cylinder gasket, or vacuum hose. The brake booster relies on vacuum pressure to do its job.
Faulty ABS Module

The ABS pump in the braking systems tends to carry some braking fluid. Some seals hold it in place, but if they get worn out, it can cause the fluid to start leaking out.

Yes master cylinders can fail without leakage, the clutch master cylinder has a piston inside and there are separate channels for hi-pressure line and return(low pressure) line and their location in the cylinder differs for manufacturers.
Brake pedal difficult to push – The most common sign of a brake booster leak is your brake pedal feeling “harder” than normal. It will require more force to work and increase your stopping distance. If you notice this, you should get your car inspected as soon as possible. This is because it can affect your safety.
Stiff brake pedal action is a strong indicator of brake booster failure because the booster will have lost its ability to amplify the force of your foot to the brake, requiring you to use more pressure.
This can be due to a number of problems: a leak in a brake line, a loss of pressure within the master cylinder itself due to a failed seal, or air being introduced into the braking system. Your first reaction to encountering spongy brakes should be to rapidly pump the brake pedal with your foot.
Usually, your brake pedal will sink if the ABS or master cylinder cannot maintain the proper hydraulic pressure. This inability to maintain hydraulic pressure will not only make your brake pedal sink to the floor, but it will also make it much more difficult to stop your automobile.
Illuminated Warning Lights

An illuminated ABS warning light is the most common sign of a bad ABS module. The stability control light, traction control light, and other warnings will also likely turn on.

Bench bleeding is especially useful with new master cylinders. It`s a great way to get air out of the cylinder itself and begin your brake bleeding process quickly and easily. You can get bench bleeding kits from any number of places, but we picked ours up at Classic Performance Parts when obtaining a brake kit.
Some signs that your vehicle may have a bad brake caliper can include abnormal noise, reduced braking ability, fluid leaks, or the feeling that your vehicle is pulling to one side. Unlike brake pads that should be replaced consistently, calipers ought to last with the vehicle.
Brake Booster Check

With the car turned off, pump the brake pedal four or five times until you get a hard brake pedal. Continue to hold the brake pedal down with moderate pressure and start the vehicle. The brake pedal should drop.

Hissing. A hissing noise is usually the brake booster leaking air. There could be a leak in the vacuum line, the booster diaphragm, or the master cylinder. A small leak could cause a hissing sound when you press on the brake pedal or let off.
Brake pulsation usually only has one cause, which is warped rotors/brake discs. The main cause of warped rotors is excessive hard braking or fast stops which can severely overheat the discs.
If your foot slowly sinks to the floor with normal pressure on the brake pedal, the master cylinder is leaking internally. To diagnose a clutch master, clamp the rubber fluid line near the slave and press the clutch pedal. If the master cylinder is good, the pedal won`t move.
Use a screwdriver to press and hold the plunger in the rear of the master cylinder. The plunger should be very firm, if not immovable, past a few millimeters. If the plunger keeps moving in, this indicates a fault of at least one of the internal seals.
Unless the ABS system is actually activating, that system would not be implicated as a “cause” of the poor acceleration. In any event, once the ABS codes are read by the mechanic using a scanner, it will be evident what is wrong with that system.
In order to operate, your ABS system needs electricity. This is controlled by the anti-lock fuses and relay. The first fuse (a 10 amp fuse) must be good in order for electricity to flow to the relay, and the relay must function to provide power to the second fuse (a 30 amp fuse).
Without a scan tool capable of reading ABS codes, a visual inspection is the easiest thing to do when diagnosing an ABS light. ABS sensor wiring can be inspected from underneath a vehicle that is safely supported on ramps — you may not even need to take the wheels off.
Air as cause of malfunction

As far as the hydraulic clutch is concerned, the following symptoms may occur: Change of the pedal travel. Difficulties in disengaging the clutch. Imprecise pedal feel.

Most master cylinder failures are caused by leaks developing around the piston seals. As the piston seals wear or the cylinder bore becomes scuffed or pitted, piston seal leaks cause a falling or spongy feel in the brake pedal.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Changed brake pads and no obvious fluid leaks, brake pedal goes to floor with no resistance.
ANSWER : When you replace your brake pads you had to push back the caliper pistons to get the pads out and the new ones in. After the calipers are put back on you will have to pump the brake pedal several times to pump it up using short strokes.

If you pushed the pedal to the floor then you may have to pull the pedal back and then use short strokes until you get a hard pedal. This is normal. Now after you try pumping the brakes up and the pedal keeps going to the floor, then you either have a leak somewhere or the master cylinder has excessive debris inside it and caused the pistons to get damaged. You would need to replace the master cylinder. If you want to have this looked at in person before doing a repair, a certified technician from YourMechanic can come to your home or office to verify the cause of your braking issue first.

Read Full Q/A … : Changed brake pads and no obvious fluid leaks, brake pedal goes to floor with no resistance.

Supportive bar attached to brake pedal interrupts proper braking process
ANSWER : It’s possible to have someone alter the brake pedal or adapt a brake pedal from a different vehicle. You may call around to some customization shops to see if anyone is interested in taking on the project. But first, I would try reaching out to the selling dealer with your concern – especially since it is a new model. Good luck.

Read Full Q/A … : Changed brake pads and no obvious fluid leaks, brake pedal goes to floor with no resistance.

Brake pedal goes 3/4 way to floor
ANSWER : Hello there. This is a more unusual problem, especially given the amount of parts you have replaced. In most cases, the pedal travel is due to either the master cylinder or the brake booster, sometimes both.

Given that these have been replaced, there may be other causes. The most likely fault that comes to mind would be that there may be air in the brake fluid system or one of the brake calipers could be stuck requiring extra travel to engage.

This can occur over time and brake fluid attracts moisture or from replacing the brake components. Some vehicles may be difficult to remove all of the air from when bleeding and require the vehicle to be bleed different ways. If the brake system was vacuum bled then it may need a mechanical bleeding to resolve the issue. If you would like to have this done, a certified mechanic can diagnose your brake pedal issue and determine what should be done next.

Read Full Q/A … : Changed brake pads and no obvious fluid leaks, brake pedal goes to floor with no resistance.

Why is my brake pedal going all the way down to the floor?
ANSWER : If you are having to refill the brake fluid from it getting low and the brakes go to the floor means you have a leak in the brake system somewhere. You may have a broken brake line, leaking wheel cylinder or caliper. You should not drive the vehicle until the brake system is inspected and repaired from the leak.

Read Full Q/A … : Changed brake pads and no obvious fluid leaks, brake pedal goes to floor with no resistance.

Low brake pedal and anti-lock brakes are not kicking in.
ANSWER : The brake pedal is working to stop the vehicle, but there may be air in the controller unit causing the ABS brakes to not function. I recommend bleeding the brake system from the farthest location from the master cylinder to the master cylinder including the ABS unit. If the brakes are still spongy after a full bleed, then the controller will need to be replaced. If you need further assistance with your brake pedal being spongy, then seek out a professional, such as one from Your Mechanic, to help you.

Read Full Q/A … : Changed brake pads and no obvious fluid leaks, brake pedal goes to floor with no resistance.

Brake pedal has very little resistance
ANSWER : From what you’ve described, I’d advise you to not drive the vehicle and get the brakes bled out. It’s possible that you still have a brake fluid leak in this case.

I’d suggest having this looked at by a certified technician, like one from YourMechanic, who can diagnose your brake system firsthand and bleed your brake system if necessary. Best of luck.

Read Full Q/A … : Changed brake pads and no obvious fluid leaks, brake pedal goes to floor with no resistance.

Brakes are failing no fluid leaks at all and brake fluid resevoir still full
ANSWER : An internal seal failure in the master cylinder is possible and that is easily tested for by either blocking off the master cylinder ports and/or using pressure gauges to measure pressure developed within the system upon pedal application. It is possible that the problem is due to present air in the system or a leak that has admitted air on repeated application of the brakes over time. Of course, the system can be thoroughly bled to rule that possibility in or out. If the wheel bearings are loose, that will cause excessive pedal travel. Also, it is possible that a clogged proportioning valve could play a role in this. To answer your question about safety of operation, you are right that in this particular scenario, it is manifestly unsafe and unwise to operate the vehicle until it is repaired. If you desire that this problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a low brake pedal diagnostic and the responding mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic.

Read Full Q/A … : Changed brake pads and no obvious fluid leaks, brake pedal goes to floor with no resistance.

Brake sensor is to sensitive causing brakes to flicker while driving. 2005 Mercury Montego
ANSWER : Hi there – your brake light switch needs a minor adjustment. It is adjusted too "tight" or close to the brake pedal lever, or possibly has failed. Adjusting/replacing it will eliminate this flickering problem. I recommend a brake light isn’t working inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.

Read Full Q/A … : Changed brake pads and no obvious fluid leaks, brake pedal goes to floor with no resistance.

Eric smoalih

I am a certified master technician with the National Institute for Automotive Service Excellence (ASE), and I have been working as an auto mechanic for over 15 years. I am passionate about my work, and I take great pride in helping people keep their cars running smoothly.