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Squealing Brakes? Don't Ignore These 5 Signs of Trouble!

During the 2023 Brake Safety Week, over 12.6% of commercial vehicles had brake problems. AM PM Diesel Services lists five signs your truck's brakes need attention for safety and cost-effective repairs.
April 1, 2024
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5 min
Squealing Brakes? Don't Ignore These 5 Signs of Trouble!

Did you know that during 2023 Brake Safety Week, over 12.6% of inspected commercial vehicles were taken out of service due to brake-related violations? A squealing sound may seem like a minor annoyance, but it could be a signal of a much larger problem. 

In this article, AM PM Diesel Services will explain the five key signs that your truck's brakes need attention, empowering you to ensure your safety and avoid costly repairs down the road. By understanding these signs and taking prompt action, you can keep your brakes in top condition and your semi-truck brakes rolling safely.

Sign #1: Your Brakes Are Squealing

We'll start with the most common warning sign: squealing brakes. While an occasional squeal might not be a cause for immediate concern, persistent or loud squealing is a definite red flag. This sound is often caused by friction between the brake shoes and drums when the brake lining material wears down.

This grinding action produces a squealing noise and indicates that your brake shoes are nearing the end of their lifespan. Ignoring this warning can lead to metal-on-metal contact between the drum and shoe, causing significant damage to your drums and potentially leading to brake failure. If you hear a persistent squealing noise when braking, it's time to schedule a truck brake service to have your brake shoes inspected and replaced if necessary.

Abnormal Vibrations When Braking

If you feel a shaking or pulsating sensation in the brake pedal or steering wheel when applying the air brakes, it's a sign of a potential problem with your truck brake system. This vibration can be caused by several factors, including:

Warped brake drums: Overheating from excessive braking or worn-out brake shoes can cause drums to warp, leading to uneven braking pressure and vibration. In severe cases, warped drums can also cause a pulsating feeling in the brake pedal.

Loose wheel components: Loose lug nuts or other loose components on the wheel can cause the entire wheel to wobble when braking, resulting in vibration. Always ensure your lug nuts are properly torqued after any wheel service.

Imbalanced tires: Imbalanced tires can also vibrate, and this vibration can be mistaken for a brake problem. However, a vibration caused by unbalanced tires will typically be felt throughout driving, not just when braking. Schedule routine tire balancing and wheel alignments to prevent this issue.

It's crucial to have a qualified mechanic diagnose the cause of the vibration during a truck brake service and address the issue promptly to ensure safe braking performance. Ignoring vibrations can lead to premature wear and tear on other brake system components.

Increased Stopping Distance  

One of the most critical signs of brake trouble is an increase in the distance it takes your truck to come to a complete stop. This can be caused by several factors, including:

Worn-out brake shoes: As brake shoes wear down, there is less material available to create friction with the drums, reducing braking effectiveness. This is why it's important to replace your brake shoes before they wear down completely.

Leaking air: A leak in the truck air brake system can reduce air pressure, leading to spongy brakes and a longer stopping distance. If you notice a spongy brake pedal, don't hesitate to pull over to a safe location and have your brake system inspected for leaks.

Contaminated brake shoes: Oil, grease, or other contaminants on the brake shoes can reduce their ability to grip the drums, compromising braking performance. Contamination can occur from leaking axle seals or from driving through deep puddles or mud. If you suspect your brake shoes are contaminated, they will likely need to be replaced during a truck brake service.

If you notice that it's taking longer than usual for your truck to stop, don't hesitate to pull over to a safe location and have your brakes inspected by a qualified mechanic. Increased stopping distance is a serious safety concern that should not be ignored.

Uneven Brake Shoe Wear

Uneven wear on your brake shoes can be another sign of a problem with your braking system. This can be another sign of a problem with your braking system, and it can be caused by a variety of factors, such as:

Rusted/missing springs: If brake shoe return springs become rusted and seized or are missing altogether, the brake shoes may not retract completely from the drums. This continuous contact with the drums can cause excessive wear on one side of the shoe, as the affected shoe will be constantly dragging against the drum surface. A visual inspection during routine maintenance can identify rusted or missing springs. In such cases, replacing the springs with new ones is essential to restore proper brake function and prevent uneven wear.

Improper drum alignment: While less common than the previous cause, improper drum alignment can also contribute to uneven brake shoe wear. Misaligned drums can cause the brake shoes to make uneven contact with the drum surface, leading to one side of the shoe wearing down faster than the other. A warped drum or worn hub assembly can be potential culprits behind drum misalignment. A qualified mechanic can diagnose drum alignment issues and recommend resurfacing the drums or replacing the hub assembly, if necessary, to ensure proper brake shoe contact and even wear.

Uneven brake shoe wear can compromise braking performance and should be addressed by a qualified mechanic as soon as possible. Ignoring this issue can lead to more extensive repairs down the road.

Low Air Pressure Warning Light 

Many heavy-duty trucks are equipped with an air pressure warning light for the air brake system. This critical light should never be ignored. If this light comes on, it indicates a problem with the air pressure that is essential for proper brake operation. There are several reasons why the air pressure warning light might illuminate, including:

Air leaks: Leaks in the air brake system can deplete the air pressure needed to apply the brakes. These leaks can occur in various locations, including hoses, valves, or connections. A qualified mechanic can identify and repair any air leaks in your truck's air brake system.

Malfunctioning air compressor: The air compressor is responsible for maintaining the air pressure in the system. If it malfunctions, it may not be able to generate enough pressure to operate the brakes effectively. Early detection and repair of a malfunctioning air compressor can prevent a complete brake failure.

Moisture in the air system: Moisture can accumulate in the air brake system and cause corrosion, leading to leaks and other problems. Regular draining of condensation from the air tanks is essential to prevent moisture buildup.

Ignoring a low air pressure warning light is incredibly dangerous and can lead to complete brake failure. If this light comes on, pull over to a safe location and turn off your engine immediately. Do not attempt to drive your truck until the problem has been diagnosed and repaired by a qualified mechanic who specializes in truck brake repairs.

The Importance of Regular Air Brake System Maintenance

Your truck's air brake system is a complex and vital component for safe operation. Regular maintenance is crucial to ensure its proper functioning and to prevent costly repairs down the road. Here are some key maintenance tasks to consider for your truck air brake system:

Visual inspections: Regularly inspect the air brake system for leaks, loose connections, and damaged components. Look for any signs of wear or corrosion on hoses, valves, and other system components.

Air pressure system checks: Ensure the air pressure system is maintaining the proper pressure levels as specified by the manufacturer. Low air pressure can significantly reduce braking performance.

Moisture removal: Drain condensation from the air tanks on a regular basis to prevent corrosion and ensure optimal system performance. Consult your truck's owner's manual for the recommended frequency of draining the air tanks.

Component lubrication: Lubricate caliper slide pins and other moving parts in the air brake system to ensure smooth operation and prevent potential sticking issues.

Following manufacturer's recommendations: Refer to your truck's owner's manual for specific maintenance intervals and procedures for your air brake system. Following these recommendations will help to ensure the longevity and safety of your truck's braking system.

By following a regular air brake system maintenance schedule, you can help prevent brake problems and ensure your truck operates safely and efficiently. Early detection and repair of potential issues can save you money in the long run and prevent a potential roadside breakdown.

Final Words

Don't wait for a catastrophic brake failure to address warning signs! By understanding the five key signs outlined in this article and prioritizing regular air brake system maintenance, you can take control of your truck's safety and avoid costly repairs. At AM PM Diesel Services, our team of certified mechanics has the experience and expertise to diagnose and repair all types of truck brake problems, from worn-out brake shoes to complex air brake system issues.


Hayden Mathews

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