How to Troubleshoot Car Brakes

2024 Author: Samantha Chapman | [email protected]. Last modified: 2023-12-17 09:13

The braking system of a car is essential for the safety of the vehicle. Without working brakes it is impossible to slow down or stop when necessary. Solving the problems associated with this system is not always a simple task. Each component must be in good condition to work properly and recognizing malfunctions requires some knowledge of mechanics and the ability to diagnose the specific damage.

Steps

Step 1. Study the different brake systems that are fitted to modern cars

There are two sub-systems on a passenger car: the deceleration system, with hydraulic operation that is dynamically controlled by the driver, and the parking system activated by a mechanical lock that prevents the vehicle from moving when is parked. Here are the specific problems you may encounter on each of them:

• Parking brake.

  • Failure to enter. If the handbrake does not engage, the car could start moving when it is left unattended.

    • Check the range of movement of the lever or pedal that activate the parking brake; if they reach the end of their travel without the system operating, the connection cable may be broken or the brake disc / drum is not working as it should.
    • Make sure the brake stays on when you pull it. If this does not happen, the mechanism that locks the brake in its position, whether cam or gear, is broken or badly adjusted.

  • Failure to disarm. Make sure the brake releases when you release the lever / pedal. If it does not unlock, the drive action works against the brake force, wearing it out and overheating its components.

    • A blockage of the drum / rotor components could be the cause of a faulty handbrake.
    • Damaged cables or connections can also prevent the parking brake from releasing.

  • Components of the decelerating brake.

    • The master cylinder supplies pressure to the hydraulic fluid that allows the pistons to activate the clutch components (pads on disc brakes or shoes on drum brakes) so as to slow down the rotation of the wheels. The brake pump is mounted inside the engine compartment, on the driver's side, near the wall that separates the passenger compartment from the compartment itself. Check the following to understand if you have a problem with the master cylinder:

      • Check the fluid level inside the tank. Some cars have a clear reservoir that allows you to see if there is enough brake fluid or not. In other models, however, it is necessary to unscrew or remove the clamps to remove the lid from the tank. There should be reference marks for the maximum and minimum fluid levels.
      • Check the area around the master cylinder for fluid leaks. These could indicate damage to the reservoir or pump seals.

    • The pistons cause the pads or shoes to come into contact with the brake disc or drum. They are located on each axis of the car, around the disc assembly or inside the drum brake, depending on the type of system mounted on your car.

      Check each hub for fluid leaks. You can usually do this by looking behind each wheel for obvious fluid dripping or stagnation on the inner surface of the hub-wheel-brake assembly

    

    Step 2. Try to isolate problems with a test drive

    Find an empty parking lot or a quiet side street to take this test.

    • Check the "travel" of the brake pedal by starting the engine and applying pressure to the pedal while the car is in neutral or in the parking position (if the gearbox is automatic).

      • Start with gentle pressure to understand how far the pedal moves before encountering resistance. The "game" depends on car to car, but usually it shouldn't be more than ¼ of the entire available race.
      • Press harder and hold the position to see if the pedal begins to yield or move gradually towards the floor.
      • Pump the pedal quickly a couple of times to make sure it returns to the same position each time you step on it. If the pedal stops at the highest point, then there may be air trapped in the brake hydraulic line.
    • Release the handbrake and put the first or transmission lever on Drive, release the clutch.
    • Listen for any metallic or screeching sounds coming from the axles while the brakes are not activated. When the car moves, a number of parts are involved including rotors, bearings and gears, so noise is completely normal; however, very loud metallic sounds or screeching can indicate brake damage.
    • Press the brake pedal lightly and pay attention if the noises increase or disappear. A constant friction noise indicates that the brake components come into contact evenly, while a "rattle" means that the disc or drum are deformed.

    

    Step 3. Check if the car slows down normally

    Pay particular attention to vibrations or changes in resistance that you feel on the pedal. These may warn you of the presence of air in the hydraulic system.

    Accelerate to a speed that is safe for your location, around 30km / h, and squeeze the brake firmly. Try to observe if the wheels seem to be pulling in another direction. A faulty brake can cause the car to head to the opposite side where the brakes readily “lock” the wheels

    

    Step 4. Check the visible components of the brake system

    Park the car on a solid and flat surface, even better in the garage or in the paved driveway. Wedge the wheels and jack up a tire. Add additional support if you have to work under the semi-raised car (with wheels equipped with spoked rims, the brake discs are visible even with the car on the ground).

    • Check the surfaces of the discs (if your car is equipped with this type of brakes). They should be smooth and shiny with a uniform silver color. Violet or bluish areas indicate that the discs have overheated, while rough areas, deep scratches or a stained and grainy surface are a symptom of abnormal wear or deformation of the disc.
    • If the wheel is raised, try to shake it to see if there are any abnormal bearing movements. Spin it and listen for any strange sounds or uneven brake contact. Ask a friend to step on the brake pedal to see if the wheel locks up.

    

    Step 5. Check the brake fluid

    The level should be between the minimum and maximum marks engraved on the tank. Never "top up" brake fluid if the level is not clearly below the "minimum" mark. As the brake pads wear and decrease in thickness, the piston pushing them against the brake adjusts its position accordingly, requiring more fluid. Fitting new pads allows the piston to return to its original position and therefore also the fluid level is restored. "Refilling" brake fluid when the pads are worn causes excess fluid by the time the pads are replaced.

    

    Step 6. Replace the brake pads

    If you hear a screeching or clicking noise when you brake, it could indicate that you need to change the pads. Excessive dust on the wheels is also a symptom of this, as well as noisy or vibrating brakes. It is also often a good idea to turn or replace the discs during this operation.

    

    Step 7. Ask the mechanic to check your brake booster system

    If this unit is malfunctioning, the pedal must be depressed more than usual to apply the brakes.

    

    Step 8. Check the brake booster for leaks

    If the pedal is very hard to step on, then the brake booster needs to be repaired.

    

    Step 9. Drain the fluid from the brake system and replace it with a new one

    Contaminants within the hydraulic system can cause problems in proper operation. If the pedal has to be depressed more than normal to activate the brakes, then there may be a foreign agent in the fluid.

    

    Step 10. Examine the brake system and replace any broken or damaged components

    A hard pedal indicates a break or blockage in the system.

    

    Step 11. Install a new master cylinder

    If the pedal seems to have no pressure and the car is not braking as it should, perhaps you need a new pump.

    

    Step 12. Check the disks

    If the brakes are noisy or vibrate, this could be due to bad discs. The problem could lie with just one drive or all four.

    Warnings

    • Be very careful with brake fluid as it can corrode body paint very quickly. Any drop that falls on the paint must be removed immediately.
    • Brake dust can (and often does) contain asbestos. Never clean the brakes with compressed air as it releases the asbestos particles into the air that you will eventually breathe if you do not wear specific protection. Clean them with a specific detergent or water.