Q&A for How to Troubleshoot Your Brakes

This may be caused by poor brake adjustment or uneven brake fluid pressure in the system.

This may be caused by a caliper not releasing, a pad binding, or an issue with an emergency brake not releasing.

This can indicate warped or torn rotors or unevenly worn brake pads. Extremely hot rotors can cause warping, while inconsistent pad wear may be caused by poor installation, bad retention springs, or issues with the brake calipers.

A grinding noise usually indicates serious issues with pads or rotors. It can also be caused by road debris getting caught in the brake pads and rotors.

Most likely a bad master cylinder, or brake booster, if your car is equipped with it.

Inspect all the wheel cylinders, lines, and the calipers for leakage. Look for damp areas around the lower section of each brake drum or caliper. If there are no signs of leakage, than bleed the entire system over; pay close attention to the line from the master cylinder to the brakes. Also, look up the proper order to bleed the wheels; this is very important.

If your brakes do not work and your pedal is really hard, the only thing it can be is a brake booster. Make sure the vacuum line connected to the booster is not clogged or disconnect it and try the brakes.

That depends on what you mean by "hard" and "normal." If you mean it's difficult to stop the car, then you have a leak in the brake booster system. If you mean the pedal feels hard to press, then when it goes to "normal" is when you may have developed an air bubble in your brake lines and need to bleed them.

Sounds like a leak in the booster or lines. Do a thorough check of hoses and both booster and master cylinder.

The master cylinder may fail because of contaminated brake fluid, which swells seals and makes them soft and ineffective. As fluid ages, it absorbs moisture and lowers the boiling point of the fluid and will destroy the seals. There are replenishing and compensating ports for each piston. These ports may be clogged up, sometimes when people open brake fluid they may get pieces of foil in the bottle they then pour fluid in the master cylinder, clogging it.

If you have ever had your rotors machined, you need to measure them. When machining a rotor, you remove mass. This could cause the rotors to heat up faster.

No the master cylinder is in front of the booster. Servo refers to drums.

You have air in the system, they need to be bled. This will fix that problem.

Try replacing rotors and your calipers. Some brake systems need to be bled in a certain order.

By visual inspection. The master cylinder leaks inside the driver side. The lines start from the master cylinder and end in the wheels; there are connection blocks for ABS and valves plus hose connections that all need to be visually inspected. Lines can get damaged under the vehicle by objects on the road, or poorly-positioned lifting equipment. Vibrations can cause a loose and broken line. Rust inside and outside can cause line leaks. But when brake pads just wear out this makes the brake fluid level go down in the reservoir and give a false idea of a nonexistent leak. Keep a record of fluid refills for the time when new pads will be installed and remove that amount to prevent overflow.

It could be that air entered the system, and it needs to be bled. It could also be air seal leakage in the brake amplifier or a defective brake amplifier.

Get off the road as soon as it is safe, turn on your emergency flashers, and contact roadside assistance (AAA, OnStar, or other) or a towing company. Do NOT continue to drive a car with defective brakes.

Test your metering valve. This valve ensures the rear gets pressure before the front, so when you brake, the rear wheels do not slip when the car dips forward.

It could be worn brakes. You should check pads immediately if you have disc brakes.

No, you do not. Bleeding is only necessary if you replace parts in the fluid system. You should flush and bleed every 5 years or so.

Of course, otherwise it is impossible to install them. It's best to do this with a clamp.

Brake boosters are designed to hold a vacuum when the engine stalls to allow you two or three power assists. This is a good test -- get in the car, press the pedal until it is hard to press further, then hold your foot on the brake pedal and start the engine. The pedal should sink to the floor if your car is operating normally.

If you have floating rotors and the piston pushes the inner pad to the rotor, the caliper then slides because of the slide pins. Grease the edges of the pads and the opposite side of the friction materials where the piston or bracket makes contact. The grease acts as a cushion, so you won't hear the clicking noise.

When rotors get hot and water gets on them, it creates hard spots. Hard spots cannot be machined, so you will have to replace the rotors.

This could be a problem with the master cylinder. It has a return spring that pushes the primary and secondary pistons back, which pushes the booster's pushrod, then the pushrod connected to your pedal. Some vehicles have a return spring for the pedal assembly; the spring can be worn, broken, or even missing.

More info is needed, as each make and model can be slightly different. If you have a car with rear disk brakes the procedure is different than a car with rear drum brakes.

Jack up your car and look at the brake pads. They should be at least 5mm thick. If less, they need to be changed. If you have a fairly modern car, check your dash lights. Modern cars have brake sensors.