[SOLVED] Chevy Silverado Clunking Noise When Accelerating

You’re driving your Chevy Silverado peacefully down the highway when suddenly a loud clunking noise shakes you out of your reverie as you accelerate. That’s definitely not normal. It can be quite concerning to hear a clunking noise, but you don’t have to be too worried about it. While a clunking noise is a symptom that there’s something wrong with your Chevy, it’s easily diagnosed and fixed.

It’s also a very common problem. Chevy owners will retell stories of how they’ve been getting ‘the clunk’ with their vehicle over the past few decades and what seemed to solve it for good. We’ve gathered all that valuable information into this article, along with expertise from mechanics so that you don’t need to keep visiting a mechanic all on your own. 

Why Does the Chevy Silverado Make a Clunking Noise when Accelerating? [Common Reason]

Clunking noise during acceleration in a Chevy Silverado may be caused by drivetrain or suspension issues. Possible causes include a worn driveshaft, loose/broken suspension component, or transmission problems. Get the vehicle inspected by a mechanic and make necessary repairs.

Reason Why Chevy Silverado Make a Clunking Noise when Accelerating?

To understand why Chevy Silverado makes clunking noise, you need to understand how ignition works. 

So, the engine burns air and fuel mix repeatedly. When the spark plug sparks 10 to 40 degrees before the top dead center. It results in a flame kernel by spark around the spark plug’s electrode. 

As the kernel increases in size and temperature, the heat and pressure around it increase to near its ignition point. Here, the hot gasses produced by combustion generate a pressure wave, which forces the piston down.

There are a few explanations as to why your Chevy Silverado makes a clunking noise when you accelerate. Here are the most common ones: 

• Engine Knock
• Accessory Pulley
• Dry Yoke
• Rod Knock

However, if you’re struggling with starting your Chevy Silverado, such as an issue where it cranks but doesn’t start: check out our article on that separate issue here. 

Top 4 Reasons For Chevy Silverado Clunking Noise When Accelerating

Here are the most common and probable reasons why your Chevy Silverado is making a loud and strange clunking noise when you try to accelerate it. 

Most of these reasons are not extremely serious and it’s definitely possible to fix them on our own. This issue particularly doesn’t really need the expertise of a mechanic in most cases, so you can save money and time by trying to deal with the issue on your own. 

Reason #1: Engine Knock

This is one of the most common explanations for the clunking problem. What exactly is an engine knock? An engine knock is a problem that occurs when only one portion of the fuel is detonating much earlier than the rest of the fuel. This takes place in the cylinder. The uneven timing of the detonation of some of the fuel is what causes the issue since all fuel should ideally detonate equally and at the same time for smooth and efficient functioning. The fuel is not supposed to be detonating by itself in the cylinder. 

The ideal functioning occurs when the spark plug triggers the combustion and burns up the entire amount of fuel that’s present in the cylinder. This results in a controlled and complete combustion process. 

Solution: So why does this happen? What causes only a portion of the fuel to detonate earlier than the rest? The culprit for this is most likely the octane rating of your fuel, which can be too low and cause this problem. While the octane rating is the most likely reason why this is happening, it’s also possible that there’s something wrong with the functioning of your engine.

Another common mistake that you might be making is adding the wrong fuel in your vehicle. If your vehicle requires premium fuel, and you’re adding regular fuel: this is a recipe for disaster and will almost certainly cause the Engine Knock issue which is the clunking noise that you’re hearing so frequently. Ensure that you’re using the correct fuel that’s intended for your vehicle. 

If you’ve performed all these checks and it seems that everything is working perfectly, you might want to check out the knock sensor itself, as this might be faulty. Additionally, the wrong fuel-to-air ratio can also cause untimely combustion, leading to the engine knock. 

Reason #2: Accessory Pulley

While this is a slightly less common explanation, it still might be a valid reason as to why you’re experiencing the strange clunking noise. 

Have you ever wondered how the water pump, power steering pump, air conditioning compressor all work in the vehicle? No? Well, you’re about to find out. 

Near the engine in the vehicle, there’s an accessory pulley. This looks very similar to a conveyor belt, and it moves a couple of pulleys that affect all of the “accessories” (the pumps, A/C, and more). This movement is what powers the accessories and allows them to continue functioning while the vehicle is in movement and driving. 

Solution: If the pulleys are cracked, bent, or rusted over with corrosion, they will rattle and make a loud clunking noise as your engine spins faster. This explains why you’d start to hear the sound only after you accelerate!

The easiest way to deal with this issue is to replace the pulleys that are malfunctioning. You will have to open up your vehicle to locate the damaged pulleys, but this can be done by a layman such as yourself — since it’s easy to spot the guilty pulley as it will be obviously damaged. 

You can source a replacement accessory pulley and easily do the replacement yourself!

Reason #3: Dry Yoke

This is one of the easiest issues to solve. All you would need to perform in this particular issue is whip out the good old lube. Let’s explain. 

The clunking can come from the slip yoke, which tends to get dry and under-lubricated through continuous use. 

Most people face this particular case and take their vehicle straight to the mechanic. All the mechanic does is use a bit of lubricant and charges you exorbitantly for the procedure, when you could’ve done it yourself. We recommend that you perform this lubrication yourself as one of the first steps to see if the problem goes away, and then go ahead to try and replace any parts. 

Solution: You will have to remove the yoke from the drive shaft. Once you’ve removed the yoke and have it as a separate part, you can work on applying lubricant to the spline shaft itself.

While this is easy enough, it’s possible to complicate the issue further by using the wrong lubricant. Make sure that you’re using a lubricant that is compatible with your transmission fluid. 

When they come in contact (the transmission fluid and lubricant) there should be no complications that further worsen the issue. That’s why you should always carefully read the labels!

Reason #4: Rod Knock

We hope that this isn’t the culprit for your clunking noise, but if all else fails, you should definitely consider this as one of the explanations for the issue. 

A rod knock occurs when the piston bearings inside the engine become damaged and begin to misfire. The pistons inside the engine are extremely important for the engine’s optimal functioning and if they begin to misfire, this affects the crankshaft. 

Ideally, the rod is supposed to travel up and down while the crankshaft spins in a rotational form, so any damage to the rod itself will cause an incorrect movement pattern. Most often, the clunking noise is explained by the rod banging against the crankshaft instead of allowing it to move in sync. 

Solution: While we would love to tell you to source the rod yourself and make the change, there are various complications that can arise with the procedure. It’s difficult to source the rod for one, and the exchange of the old rod to the new is also a dicey task since this is located right at the core of the engine where you could damage other parts as well.

It’s best to contact the Chevrolet dealership repair for this particular issue, but you can at least follow the preliminary steps so that you know that this is indeed the issue.

Other Reasons Chevy Silverado Makes Clunking Noise 

Besides engine knock, accessory pulley, dry knock, and rod knock, Chevy Silverado can cause clunking noise due to a variety of other factors as well. 

You might hear a clunking noise when decelerating under a vehicle or a banging noise when accelerating from a stop. Some other reasons for this to happen include: 

Too Low Octane

You might know that every car engine is designed with a specific number of octane, which determines the tolerance level of fuel to pressure. So, if the octane number is high, the greater the power output. That’s because the farther the piston will move towards the spark plug. 

But if the octane is low, it will try to reach the maximum travel by making several pockets of fuel and air mixture. It reduces the vehicle performance and also results in clunking sound. 

Bad Knock Sensor 

New model cars in the market are equipped with an engine knock sensor, which helps detect the communications with ECU. It is what diagnoses the problem. But certain times, the ECU can be defective. Meaning it can send incorrect signals to the ECU.

More air/fuel mixture is more than required in such a situation. And it results in the sound. 

Lean Air-Fuel Mixture

If the air/fuel mixture is more, the fuel portion is small. It can occur when there is an issue with the spark plugs, oxygen sensors, or oxygen sensors. 

Also, if there is not sufficient fuel in the cylinder, the burning duration of every mixture will be different. This further will result in denoting a mixture at an inappropriate time, and it causes the engine to knock. 

Carbon Deposits

Carbon cleaners are used to prevent the accumulation of carbon deposits in the cylinder. But when the carbon deposit reaches the cylinder, it can make the engine produce a knocking sound while accelerating. 

Faulty Spark Plugs 

Next comes the faulty spark plugs that generate enough power for the engine to operate. Now, with age, the spark plug gets damaged, resulting in reduced spark. 

This spark can be delayed, making the engine produce a knocking sound while accelerating. 

Low Oil Level

Low oil levels can also result in knocking sound. What happens is that when the level of oil drops, the rod bearing between the piston rod and crankshaft ruptures. After getting damaged, if it moves up or down, a rattling sound is produced. 

Why Is My Car Making Noise?

Besides making clunking noise while accelerating, your car can make many other noises. Even if you take excellent care of your vehicle, it is likely to make loud noises. But you must not get afraid of the sound. Instead, you should get it fixed. 

Below are some reasons to help you understand why your vehicle has been making irritating noise lately.

Engine Knocking 

If you notice engine knocking noise, it can be due to low-quality fuel. To stop the noise, you can change the fuel. 

Besides low-quality fuel, rod knock can also result in noise around the engine. It’s a serious problem, and for this, you must get professional help. 

Clunking Noise When Braking 

If you hear a clunking noise while pressing brakes, you must not take it lightly as it’s a bigger problem than you realize.

Generally, this sound is caused by various factors, including loose wheel bearing, seized brake caliper, or worn-out ball joints. 

The presence of any of these problems can put you at risk of getting injured as the wheel won’t move how you want them to, or the brakes won’t work well. So, if you think there is a problem with the brakes, you must get professional help without wasting any time. 

Random Car Noise at High Speed

Is the sound you hear close to rattling, flapping, or knocking? If so, it indicates that there is something loose in the vehicle. It can be anything, from the trim to the bumper cover. 

When you hear the noise, you must figure out the exact source of the sound. If you frequently hear the noise, there is something loose inside the car. But if the car starts making noise at a certain speed, there is something wrong internally. 

Knocking Sound When Starting the Car 

If you hear a knocking sound when starting the car, it shows a problem with the transmission’s flexplate. Or it can be due to the starter. 

Either of the issues is serious, and you must get professional help as soon as possible. If the sound is coming due to a problem with the starter, the fixing can be done in a day. But fixing problems related to the transmission’s flexplate could cost a lot of money. 

Knocking Sound on Bumpy Road 

Do you often hear knocking sounds when driving on bumpy roads? If so, it can mean that you have a problem with the suspension. If you don’t want to invite any serious problem, you must take professional help quickly. 

Frequently Asked Questions 

Conclusion

We hope that you were able to resolve the clunking noise issue all by yourself. Three of the reasons we mentioned in this article — engine knock, accessory pulley, and dry yoke; are all easily rectified by yourself without the need to call a mechanic. 

However, if it happens to be a rod knock that you’re dealing with, you will have to book an appointment with your local mechanic. Good luck!