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Semi Truck Grinding Noise: 11 Causes You Shouldn’t Ignore!

Hearing some weird and unusual sounds on your semi-truck is a common scenario. However, it is also an indication of an underlying issue.

A grinding noise is a sign of several issues in your semi-truck, such as problems with the transmissions, losing bolts and bearings, faulty gears, and many others.

This post will tackle grinding noise in a semi-truck, what’s causing them, and what you can do to prevent them from getting worse.

Here’s Why Your Semi-truck is Making a Grinding Noise:

Semi-truck grinding noises typically occur due to worn-out components such as transmission bearings, wheel bearings, brake pads, cv joints, engine mounts, clutch, gears and low transmission fluid. These noises may be experienced while your semi-truck is accelerating, coasting or slowing down.

Semi-truck Grinding Noise When Driving

When driving, you can hear a grinding noise in your semi-truck is the most common scenario. When you try to coast, accelerate, or slow down, there are instances when you can listen to one.

Though it is customary to hear these kinds of noises when driving a semi-truck, sometimes they serve as a reminder for you to check it up. 

Semi-truck Grinding Noise When Coasting

It is suspicious to hear a grinding noise when coasting or driving in neutral, and you have pressed down the clutch. That’s why if you think there are more weird noises than usual, you should not ignore them.

The typical indication of grinding noise when coasting is a bearing issue in the transmission. The small bearings found on the back of the input shaft are the possible culprit of this sound.

To fix it, remove the transmission and the top cover to see other internal parts near it for inspection.

Semi-truck Grinding Noise When Accelerating

Like any vehicle, you can also hear a louder sound from your semi-truck as soon as you accelerate. But sometimes, you may hear something different from its usual sound.

A grinding sound when you accelerate is an indication of several possible issues. It includes problems with the transmission, worn-out engine or motor mount, bad wheel bearings, or damaged continual velocity (CV) joints.

There are specific ways how you can fix each of these possible issues. If the transmission is the cause, replacing it with a new one is better.

However, please refrain from doing it yourself since the transmission has complex and sensitive parts. Always ask for professional help instead.

For a worn-out engine or loosened motor mount, you can fix it yourself if you have the right tools. Always ensure that you secure it in its place to avoid it from loosening again.

If the culprit is bad wheel bearings, replacement is the best solution. You can handle it if you have the skills and knowledge, but if not, take your semi-truck to an automotive repair shop instead.

Lastly, for damaged CV joints, you also need to replace them. The replacement may cost you up to $500 for the parts and up to $800 for the labor.

If you have the skills and experience to do it yourself, you may only have to spend about $200.

Why Does My Truck Make a Grinding Noise When it Slows Down

Another instance when you may hear grinding noises in your semi-truck is when you slow down.

The leading cause for these noises can come from the alternator or wheel bearings, brake pads, and velocity joints.

Examine each of these parts as soon as you encounter a grinding noise when lowering your speed. That way, you can pinpoint the exact issue and have it fixed.

To avoid further damages and expenses, it is always better to seek professional help with your semi-truck instead of fixing it yourself.

Semi-truck Grinding Gears

Grinding gears are an indication of a faulty transmission in your semi-truck. When it happens, most of the time, there is disengagement in the clutch.

There are also other causes for grinding gears, which you should learn about to avoid misdiagnosing the issue of your semi-truck.

What Causes the Gears to Grind?

The most common reasons for grinding gears are:

  • Clutch problems.
  • Torque converter problems.
  • Low transmission fluid.
  • Gear system damage.
  • Internal transmission damage.
  • Bad driving habits.

The clutch is usually the main culprit of grinding gears, usually when shifting.

In other cases, the transmission is also responsible for the noise, particularly the torque converter.

Lack of transmission fluid can also lead to internal transmission damage. Aside from this, you also need to check thoroughly to see possible signs of old or corroding transmission. In that case, you should replace it.

Apart from all the mechanical issues that lead to grinding noise, your driving habit may also be a culprit.

Frequent usage of aggressive shifting, carrying loads beyond the capacity of your semi-truck, or other careless driving actions can also cause grinding noise which you should not ignore.

Does Grinding Gears Damage Transmission?

Occasional grinding gears are a regular occurrence when driving a semi-truck. However, frequent grinding can cause damage to the transmission and gearbox.

When left ignored, grinding gears can also cause problems for the engine. It is a rare occurrence, but it is likely to happen.

Once you experience some issues on any of the mentioned parts because of grinding gears, you will most likely have regular vehicle jerks when driving and excessive fuel consumption.

Eaton Fuller 10-Speed Transmission Grinding

The Eaton Fuller 10-speed transmission can cause grinding, especially when you switch it to low. If it happens, the possible reason is an unsynchronized transmission to the semi-trucks engine.

The most appropriate solution is to remove the rear part of the transmission without pulling it. You can drag the covers of the countershaft and brace it to reinstall the auxiliary section of the transmission.

Truck Grinding When Starting

As soon as you start the semi-truck, its engine produces a sound indicating its good performance.

However, there are several occurrences when you also encounter grinding noises while turning on the ignition or shortly after the engine has started.

Grinding Noise When Turning the Key in the Ignition

You expect the engine to crank when you turn the key in your truck’s ignition. It usually happens when the ignition and the charging system are in good condition. However, it might not often occur.

The common reasons are:

  • Bad starter drive gear.
  • Lousy starter solenoid.
  • Bendix clutch dust contamination.
  • Dead battery.

If your semi-truck experiences a grinding noise as soon as you turn the key ignition, allow a professional mechanic to inspect and troubleshoot to fix it.

Starter Motor Noise After Starting

You should only hear a short whir every time you turn the starter motor. If there are grinding noises that prolong this sound, there is a possible underlying issue you should not ignore.

The best possible reason a grinding noise is present when starting the semi-truck is the misalignment of the starter from the ring gear. Other causes include damaged or missing gear teeth and a damaged solenoid.

To fix this problem, replacement is the most suitable solution. It is not a complicated repair procedure. You only need to replace the starter or the solenoid and install the new gear.

Semi-truck Brakes Grinding

The brakes can also cause semi-truck grinding noise. It can appear when the brake friction material or brake linings have worn out.

Another cause is if the steel brake rotor rubs against the metal brake pad backing. When it happens, contact between the two creates a grinding noise.

Grinding Noise When Braking but Pads are Fine

Usually, you can hear a grinding noise when braking if the semi-truck already has worn-out pads. But sometimes, it is not always the case.

Suppose you already checked and see that the pads work fine.

In that case, the possible indication of the grinding noise can come from the solid lodged between the caliper and the rotor, worn-out rotor discs, broken shims, unlubricated caliper bolts, and broken wheel bearings.

If you haven’t used the semi-truck for a long time, it can also cause a grinding noise. You may check the pads to see if they still have proper lubrication and haven’t worn out yet.

Brakes Make a Grinding Noise When Stopping

If you hear grinding noises when stopping or slowing down, the brake pads of the semi-truck are most likely the issue.

The brake pads lose their quality and thickness over time. You can hear grinding noises as soon as it occurs due to the brakes scrubbing off.

Why are My Brakes Grinding After New Pads and Rotors?

There are rare occurrences that even when you have new pads and rotors, there is still grinding on the brakes.

If you have a similar experience, check if rust builds up on the brakes. It can occur due to moisture, lack of lubrication, and misalignment of the brake clips.

You can fix it quickly, and you should not experience any grinding. If it persists, a visit to an automotive can solve the issue.