AUTOOL Blog

Common Abnormal Issues with Car Brakes

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 risks and issues after long-term use or poor maintenance.

This article helps you understand and actively check common brake problems. Regular inspection can reduce safety hazards, extend the lifespan of your car brakes, and make every braking action safer and more reliable.

Pedal Feel

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. Braking force can drop sharply, so the system should be inspected and repaired immediately.

Hard or Stiff Pedal

When the brake pedal requires excessive effort, it may indicate a vacuum booster failure, loss of assistance when the engine stalls, or a leak in the vacuum lines. Check the automobile brakes assist system.

Long Pedal Travel

If you need to press the pedal deeper than usual to achieve braking, the cause is often excessively worn brake pads or issues in the brake lines. Replace worn pads promptly and inspect the brake fluid and lines.

Vibration and Noise

Vibrations During Braking

Steering Wheel or Vehicle Shaking

If the steering wheel or car body shakes violently during high-speed braking, it is often caused by car brakes rotors overheating, warping, or wearing unevenly. This causes uneven braking force and can affect vehicle control.

Pedal Pulsation Without ABS Activation

If the brake pedal bounces without ABS intervention, it may indicate an uneven rotor surface or a damaged bearing. Inspect and repair the automobile brakes system in time.

Sharp Metal Sound

A sharp metallic noise usually means the car brakes pads are worn to the limit. The warning plate may be rubbing directly against the rotor. Continuing to drive can damage the brake rotors, so immediate replacement is necessary.

Persistent Friction Noise

Continuous friction noise may indicate a foreign object, such as a small stone, embedded in the automobile brakes pads. It can also come from improperly installed components. Inspect, remove debris, and ensure all parts are correctly fitted.

Noise After Braking

If noise remains after releasing the brake, the caliper may not return properly. This can cause dragging and may lead to overheating.

Brake Service Tools

Brake Fluid Bleeding and Exchange Tools

The original vibration and brake service section included AUTOOL AST603, AST605, AST612, and AST618. These are preserved as product shortcodes for brake fluid bleeding and exchange workflows.

Warning Signs

Significantly Increased Braking Distance

  • Excessive Wear on Brake Pads or Rotors: Worn-out pads or rotors reduce braking efficiency. Inspect them and replace them if necessary.
  • Aged Car Brake Fluid: If car brake fluid is old or contains too much water, its boiling point decreases and braking performance drops. Regularly check and replace the fluid to maintain safety.
  • Reduced Tire Grip: Worn tire tread or incorrect tire pressure can increase stopping distance. Inspect the tires and ensure they are properly inflated and in good condition.

Car Brake Warning Light Illumination

  • Handbrake not released: Illumination of the warning light is a normal reminder that the handbrake is still engaged.
  • Light stays on during driving: The car brake fluid level may be too low, the ABS may have a fault, or a sensor problem may trigger the warning.
  • ABS and ESP lights on together: This indicates a fault in the electronic braking system. The vehicle may lose control during emergency braking, so the system should be inspected and repaired immediately.

Burnt Smell or Smoke

  • Overheated brake pads: Frequent braking while driving down a long slope can cause brake fade, which is a decrease in braking performance due to overheating.
  • Dragging brakes: If the wheel cylinder fails to retract properly, the brakes rub against the wheels continuously and generate a burnt smell or smoke.
  • Partially released handbrake: If the handbrake is not fully disengaged, it keeps pressing against the brakes during driving and can eventually produce a burnt smell or smoke.
Pulling, Rain, and Leaks

Vehicle Pulls to One Side During Braking

  • Severe wear on brake pads of one side: Unequal friction causes the vehicle to pull toward the side with more effective braking.
  • Seized wheel cylinder or blocked brake line: A seized wheel cylinder or blocked line disrupts normal brake force on the affected side, causing deviation when braking.
  • Suspension system failure: Failed components such as shock absorbers can upset vehicle balance and create uneven brake force during braking.

Abnormal Braking in Waterlogged or Rainy Conditions

After driving through water, braking performance often deteriorates because a water film forms between brake pads and discs, causing temporary slippage. Gently press the car brakes several times to generate heat, dry the pads and discs, and restore normal braking.

If braking still feels weak, inspect the brake system further. Water may have entered the brake oil circuit, disrupting car brake fluid flow, or it may have caused rust on key components.

Car Brake Fluid Leak

First, check the inside of the wheels or the vehicle chassis for oil stains. Car brake fluid is typically pale yellow or transparent, which helps distinguish it from other fluids.

If the car brake fluid level is too low, air enters the brake lines and affects braking performance. In severe cases, this can cause complete loss of braking ability and create a major safety risk.

Other Warning Signs

Other Warning Signs

  • Abnormal ABS Activation: If ABS engages frequently during light braking on dry roads, the wheel speed sensor may be faulty. Incorrect sensor signals can trigger unnecessary ABS activation.
  • Cloudy or Black Brake Fluid: Cloudy or black car brake fluid indicates deterioration. Degraded fluid can corrode lines and damage components. Replace it promptly, typically every 2 years or 40,000 kilometers.
Emergency Handling

Emergency Handling Recommendations

If the car brakes suddenly fail while driving, try the following steps calmly:

  1. Pull the handbrake slowly to assist with deceleration. Do not yank it sharply, because this may cause the vehicle to spin out of control.
  2. 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.
  3. Look for an escape ramp or a friction obstacle, such as a guardrail. Gently brush against the obstacle to slow down the vehicle gradually.
Brake Fluid Testing

Money-Saving Tip: AUTOOL AS502 and AS506 Brake Fluid Testers

In vehicle maintenance, brake fluid testing is critical for driving safety. Compared with traditional methods, the AUTOOL AS502 provides more reliable data through higher sensitivity and accuracy. It detects brake fluid water content and evaluates fluid performance more accurately, helping owners and technicians determine whether brake fluid needs replacement.

The AUTOOL AS506 Car Brake Fluid Boiling Point Tester supports two modes, Normal and Brand. Users can switch based on fluid type, brand, and formula, enabling accurate detection for both regular and high-end dedicated brake fluid. The AS506 finishes fluid condition testing in just 16 seconds, improving efficiency and supporting fast maintenance decisions.

If you want to test the quality and boiling point of your car brake fluid multiple times at a more affordable price, the AUTOOL AS502 and AS506 are practical choices. They are easy to operate and support fast testing for a professional-grade maintenance experience.

Contact Hanna for brake fluid tester discounts.
WhatsApp: +86 18926477404
Email: sales@autoolstore.com

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