Why does my Mercedes-Benz make a moaning or groaning noise when I apply the brakes?

Steve Mowat

Steve Mowat

Steve Mowat, Owner of Avantgarde Automotive, began as a BMW apprentice in 1997, then excelled at McLaren and Mercedes-Benz. In 2009, he founded his business.

As a Mercedes-Benz owner, you appreciate the luxury and performance of your vehicle. However, if you’ve noticed a moaning or groaning noise when applying the brakes, it’s essential to identify the cause and address it. In this article, we will explore common reasons for this issue and provide expert tips for resolving it.

Worn Brake Pads and Rotors

Brake pads and rotors are crucial components of your braking system. Over time, they can wear down, which may result in a moaning or groaning noise when applying the brakes.

  • Some Mercedes-Benz models, such as the C-Class W204, have been known to experience faster brake pad wear.
  • To resolve this issue, you will need to replace the brake pads and rotors. You can find the specific part numbers for your vehicle in your owner’s manual or by contacting a Mercedes-Benz specialist.
  • Tools required: socket set, torque wrench, and a brake caliper tool.

Visit our Mercedes repairs page for more information on brake pad and rotor replacement.

Brake Caliper Issues

A sticking or seized brake caliper can cause the brake pads to remain in contact with the rotor, creating a moaning or groaning sound.

  • This issue has been reported in the E-Class W212 model.
  • To fix this problem, you may need to replace or rebuild the brake caliper.
  • Tools required: socket set, brake caliper tool, and a suitable lubricant for the caliper slider pins.
Brake caliper issues can cause noise when braking.

Damaged Brake Booster

A damaged brake booster can compromise your braking system and cause a groaning noise when applying the brakes.

  • The Mercedes-Benz ML350 W166 has been known to experience issues with the brake booster.
  • Replacing the brake booster can resolve this problem. The part number can be found in your owner’s manual or through a Mercedes-Benz specialist.
  • Tools required: socket set, wrenches, and a suitable replacement brake booster.

Check our Mercedes servicing page for expert assistance with your brake system.

Brake Fluid Contamination

Contaminated brake fluid can lead to reduced braking efficiency and noise when applying the brakes.

  • Regularly check and replace brake fluid to maintain optimal performance.
  • Use only the recommended brake fluid for your specific Mercedes-Benz model.
  • Tools required: brake fluid tester, turkey baster, and a suitable container for the old fluid.
Ensure your brake fluid is clean and at the proper level.

Brake Disc Thickness Variation

A variation in brake disc thickness can cause a moaning or groaning noise when braking.

  • This issue can be resolved by having the brake discs machined or replaced.
  • Specific Mercedes-Benz models, such as the S-Class W222, have been known to experience this problem.
  • Tools required: micrometer or dial indicator, socket set, and torque wrench.

Don’t Hesitate to Seek Professional Help

While these tips and advice can help diagnose and potentially resolve the issue, it’s crucial to remember that they are not exhaustive, and individual circumstances may vary. If you’re uncertain or need expert assistance, don’t hesitate to contact Avantgarde Automotive. Our experienced team of Mercedes-Benz specialists is here to help you maintain the exceptional performance and luxury of your vehicle.

Remember, these tips and advice are for informational purposes only, and we cannot be held accountable for incorrect or out-of-date information. Always consult a qualified Mercedes-Benz specialist when addressing any issues with your vehicle.

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