AUTOOL Blog
Common Abnormal Issues with Car Brakes
29
Sep
Sep
The car brakes system is the most important “safety line” while driving. It directly affects the safety of both the driver and passengers. However, this crucial safety line can develop various risks and issues if it is used for a long time or not properly maintained.
This article will help you understand and actively check these common problems. Doing so can effectively prevent safety hazards and extend the lifespan of your car brakes, ensuring that every braking action is safer and more reliable.
Abnormal Brake Pedal Behavior
- Soft or Spongy Pedal: If the brake pedal feels soft or sinks to the floor when pressed, it is usually caused by car brakes fluid leakage, air entering the lines, or a malfunction in the master cylinder. As a result, braking force drops sharply. You should immediately inspect and repair the system to ensure safety.
- Hard or Stiff Pedal: When the brake pedal requires excessive effort to press, it may indicate a failure in the vacuum booster, such as losing assistance when the engine stalls, or a leak in the vacuum lines. In this case, you need to check the automobile brakes assist system.
- Long Pedal Travel: If you have to press the pedal deeper than usual to achieve braking, it is often caused by excessively worn brake pads or issues in the brake lines. Therefore, you should replace the worn pads promptly and inspect the brake fluid and lines.
Vibrations During Braking
- Steering Wheel or Vehicle Shaking: If the steering wheel or the car body shakes violently during high-speed braking, it is often caused by car brakes rotors overheating, warping, or wearing unevenly. This leads to uneven braking force and can affect vehicle control, so you should address it promptly.
- Pedal Pulsation (Non-ABS Activation): If the brake pedal bounces without ABS intervention, it may indicate an uneven rotor surface or a damaged bearing. In this case, you should inspect and repair the automobile brakes system in a timely manner.
Brake Noise
- Sharp Metal Sound: If you hear a sharp metallic noise, it usually means the car brakes pads are worn down to the limit. The warning plate may be rubbing directly against the rotor. Continuing to drive in this condition can damage the brake rotors, so immediate replacement is necessary.
- Persistent Friction Noise: If the friction noise continues, it may indicate that a foreign object, such as a small stone, is embedded in the automobile brakes pads. It can also result from improperly installed components. You should inspect and remove any debris, and ensure all parts are correctly fitted.
- Noise After Braking: If you still hear noise after releasing the brake, the caliper may not return properly. This can cause dragging, which may lead to overheating.
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Significantly Increased Braking Distance
- Excessive Wear on Brake Pads or Rotors: Worn-out pads or rotors reduce braking efficiency. You should inspect them and replace them if necessary.
- Aged Car Brake Fluid: If the car brake fluid is old or contains too much water, its boiling point decreases, which directly lowers braking performance. Regularly check and replace the fluid to maintain safety.
- Reduced Tire Grip: Worn tire tread or incorrect tire pressure can also increase stopping distance. Therefore, you should inspect the tires and ensure they are properly inflated and in good condition.
Car Brake Warning Light Illumination
- When the handbrake is not released: Illumination of the warning light is a normal reminder. This indicates that the handbrake is still engaged, which is a standard safety prompt.
- When the light stays on during driving: This may be caused by three main issues. First, the level of car brake fluid could be too low. Second, there might be a fault with the ABS (Anti-lock Braking System). Third, a problem with the sensor could also trigger this situation.
- When the ABS and ESP (Electronic Stability Program) lights come on at the same time: This means there is a fault in the electronic braking system. In such cases, the vehicle may lose control during emergency braking, so you should have the system inspected and repaired immediately.
Burnt Smell or Smoke
- Overheated brake pads: This usually happens when you brake frequently while driving down a long slope, which leads to brake fade (a decrease in braking performance due to overheating).
- Dragging brakes: The wheel cylinder fails to retract properly, causing the brakes to rub against the wheels continuously. This constant friction then generates a burnt smell or smoke.
- Partially released handbrake: The handbrake is not fully disengaged, so it keeps pressing against the brakes during driving. This prolonged contact will eventually result in a burnt smell or smoke.
Vehicle Pulls to One Side During Braking
- Severe wear on brake pads of one side: If the brake pads on one side of the vehicle are significantly more worn than those on the other side, they will generate unequal friction during braking. This imbalance directly leads the vehicle to pull toward the side with more effective braking.
- Seized wheel cylinder or blocked brake line: A seized wheel cylinder fails to push the brake pad properly, while a blocked brake line restricts the flow of car brake fluid. Either issue disrupts the normal brake force on the affected side, causing the vehicle to deviate when braking.
- Suspension system failure : The suspension system plays a key role in keeping the vehicle stable and ensuring even contact between tires and the road. If components like the shock absorber fail, it can upset the balance of the vehicle, leading to uneven brake force and pulling during braking.
Abnormal Braking in Waterlogged or Rainy Conditions
After driving through water, braking performance often deteriorates. This is mainly due to a water film between brake pads and discs, causing temporary slippage. To fix this, gently press the car brakes several times—this generates heat to dry the pads and discs, restoring normal braking.
If braking still feels weak, further inspect the brake system. Water may have seeped into the brake oil circuit (disrupting car brake fluid flow) or caused rust on key components. Both affect braking, so a thorough check is needed to identify and fix the issue.
Car Brake Fluid Leak
First, check the inside of the wheels or the vehicle chassis for oil stains. Typically, car brake fluid is pale yellow or transparent, so this color can help you identify if the leaked fluid is brake fluid.
If the car brake fluid level is too low, air will enter the brake lines. As a result, the braking system’s performance will be affected. In severe cases, this issue can even cause a complete loss of braking ability, which poses a major safety risk.
Other Warning Signs
Abnormal ABS Activation: If ABS engages frequently during light braking on dry roads, the wheel speed sensor may be faulty. This sensor detects wheel rotation; malfunctions cause incorrect signals, triggering unnecessary ABS activation.
Cloudy or Black Brake Fluid: Cloudy or black car brake fluid indicates deterioration. Degraded fluid can corrode lines and damage components, compromising braking safety. Replace promptly—typically every 2 years or 40,000 kilometers.
Emergency Handling Recommendations
If the car brakes suddenly fail while driving, you can try the following steps:
Pull the handbrake slowly to assist with deceleration. Do not yank it sharply, as this may cause the vehicle to spin out of control.
Downshift to use engine braking. For manual transmission vehicles, downshift one gear at a time. For automatic transmission vehicles, switch to manual mode or shift into L (Low) gear.
Look for an escape ramp or a friction obstacle (such as a guardrail). Gently brush against the obstacle to slow down the vehicle gradually.
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The AUTOOL AS506 Car Brake Fluid Boiling Point Tester supports two modes—Normal and Brand. Users can switch freely based on fluid type, brand and formula, enabling accurate detection of performance indicators for both regular and high-end dedicated brake fluid.
The AS506 finishes fluid condition testing in just 16 seconds, greatly boosting efficiency. It also has a wide-range boiling point detection function, fully evaluating fluid’s high-temperature resistance. This helps users judge fluid quality, aging level and replacement cycle, providing safer, more reliable vehicle protection.
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