Grinding Noises? Squealing Brakes? What It Means for Your Heavy-Duty Truck

Don't ignore grinding brakes! Learn what these noises mean for your heavy-duty truck and how to prevent costly breakdowns with routine maintenance from Fleet Care Services.


Your heavy-duty truck is the workhorse that keeps your business moving. It tackles demanding jobs, hauling heavy loads across countless miles. But what happens when unusual noises creep into the symphony of your engine? 

Grinding, squealing, or any changes in your braking system can send shivers down any fleet manager's spine. Don't ignore these warning signs! This guide will decipher the language of your truck's brakes, helping you identify potential problems and prevent costly breakdowns. By understanding the telltale signs and implementing a proactive maintenance plan, you can ensure your trucks remain safe and avoid the hassle and expense of unexpected truck brake repair.

Understanding Your Truck's Braking System

Before diving into specific noises, let's establish a basic understanding of how your truck's air brake system functions. Unlike passenger car brakes that utilize hydraulic fluid, heavy-duty trucks rely on compressed air to apply braking force. This complex system consists of several key components working in harmony:

  • Air Compressor: This powerful pump generates compressed air, the lifeblood of the entire braking system.
  • Air Reservoirs: These large tanks store compressed air to maintain consistent braking power, ensuring your truck can come to a safe stop even after repeated brake applications.
  • Air Lines and Valves: These interconnected lines and valves act as a complex network, delivering compressed air to the brakes throughout the vehicle. They are strategically placed to allow for individual wheel braking and emergency air release.
  • Brake Drums or Discs: These rotating components house the braking materials that create friction to slow down the wheels. Depending on your truck's model and application, it might utilize drum brakes or disc brakes. Drum brakes enclose brake shoes within a rotating drum, while disc brakes utilize brake pads that clamp onto a spinning disc.
  • Brake Shoes or Pads: These consumable parts make direct contact with the drums or discs to generate friction when the brakes are applied. Brake linings wear down over time and need to be replaced regularly to maintain safe stopping power.
  • Slack Adjusters: These self-adjusting mechanisms automatically maintain proper brake lining clearance for optimal performance and to prevent excessive wear.

The Language of Your Brakes

Now that you have a roadmap of the system, let's translate those concerning noises your truck might be making:


This often indicates excessive wear on brake components. Worn-out brake linings, or severely worn brake drums in the case of drum brakes, can grind against each other. This harsh sound is a clear signal that your truck is in need of immediate attention. Ignoring a grinding noise can lead to complete brake failure, posing a serious safety hazard. It's crucial to schedule a truck brake repair to replace worn-out brake shoes or pads, and potentially resurface or replace the brake drums depending on the extent of the wear.


This high-pitched squeal might be caused by a glazed lining, a warning sign that the braking material on your brake shoes or pads has hardened and lost its effectiveness. In some cases, a dab of brake anti-noise compound applied according to the manufacturer's instructions might solve the issue. However, persistent squealing often points towards needing new brake pads or shoes. Don't wait until the squealing becomes unbearable — replacing worn-out brake linings is a relatively inexpensive preventative measure compared to the potential consequences of neglecting this issue.

Metallic Screeching

This loud, harsh screech can be alarming and indicates severe wear. Metal-to-metal contact between the backing plate of the worn-out brake linings and the drum is a serious issue requiring immediate attention. Continued operation with this sound present could lead to complete brake failure, posing a safety hazard to yourself and others on the road. Schedule a truck brake repair immediately to address this critical issue.

Air Leaks

While not a noise, a noticeable drop in air pressure or a constant hissing sound can indicate air leaks within the system. Leaks compromise the system's ability to deliver sufficient pressure for proper braking. Air leaks can occur in various places within the air line network, and finding and repairing them promptly is crucial to ensure optimal brake performance and avoid potential safety risks.

The Importance of Preventive Maintenance:

A staggering 12.6% of commercial vehicles are taken off the road during brake safety inspections due to violations! This translates to significant downtime and lost revenue for your business. Regular preventive maintenance is crucial to avoid such costly setbacks and potential accidents. Here's how to keep your trucks' brakes in top shape:

Regular Inspections

Conduct thorough visual inspections of your brake system during pre-trip checks. Look for any signs of wear, leaks, or damage to components like air lines, brake drums, or brake calipers (in the case of disc brakes). Pay close attention to the thickness of the brake linings — most manufacturers provide recommended minimum lining thickness specifications.

Schedule Brake Adjustments

Slack adjusters ensure proper brake lining clearance. They automatically compensate for wear on the linings, maintaining optimal performance. However, these mechanisms can malfunction or become seized over time. Regular brake adjustments, following the manufacturer's recommended intervals, are vital for optimal braking performance and maximizing the life of your brake linings.

Replace Worn Components

Regularly check brake pad or shoe thickness and replace them when they reach the manufacturer's recommended wear limits. Waiting until the linings are completely worn out can lead to damage to other brake system components, increasing repair costs.

Proper Spec'ing

Using the correct brake components for your specific truck and application is crucial. Overheating due to improper brake specifications can lead to premature wear and potential brake failure. Consult your truck's manual or a qualified technician to ensure you're using the appropriate brake pads, shoes, or drums for your truck's weight rating, engine power, and typical haul loads.

Final Words

At Fleet Care Services, we understand the importance of keeping your trucks operating safely and efficiently. Our team of certified technicians is equipped to handle all your truck's brake system needs, from routine maintenance and inspections to complex truck brake repair and replacements. We use only high-quality parts from trusted brands and adhere to strict industry standards to ensure your brakes are performing optimally. Our commitment to quality and customer satisfaction ensures your trucks are back on the road quickly and safely, minimizing downtime and keeping your business running smoothly.

In addition to expert truck brake repair, we offer a comprehensive range of services to keep your fleet in top condition, including:

  • Preventive maintenance: Our comprehensive PM programs can help identify potential brake problems before they become major issues, saving you money and preventing costly breakdowns.
  • DOT inspections: We can perform thorough Department of Transportation (DOT) inspections to ensure your trucks comply with all safety regulations, including brake system standards.
  • 24/7 emergency roadside assistance: Unexpected breakdowns can happen at any time. Our 24/7 emergency roadside assistance ensures you have a reliable partner to get your truck back up and running, minimizing downtime and lost productivity.

Don't wait for a grinding halt to your business! Contact Fleet Care Services today to schedule a comprehensive brake inspection and ensure your trucks are ready to conquer the road. We are committed to providing you with the expertise and services you need to keep your fleet safe, reliable, and profitable.