There are many reasons why a car thumps when driving. While many drivers will feel frustrated and worried that this is a sign of some severe problems within, fortunately, it’s not always—thumping noise when driving can be as simple as the sound of your tires.
That is not to say you should be less careful about the issues. If the problems persist without being diagnosed and repaired, there is a high chance it will cost you a hefty bill in the long run.
First, let’s look at some of the common scenarios in which there is a thumping noise in car.
Cases When A Car Makes Thumping Noise When Driving
Car Makes Thump Sound When Accelerating
If you notice a thump noise when accelerating, it might indicate that either the starter motor or the transmission mount is at fault.
In this case, the sound usually originates in the front of your vehicle, and you should notice your car making thump noise when accelerating.
Should the starter motor be bad, then every time you turn the key and push Start, the vehicle can make a clicking or thumping sound. Or, your car won’t even start properly, and the engine refuses to ignite.
In other cases, when you turn the ignition switch and start the vehicle, you can hear the starter working, but the motor is not cranking.
It can happen for many reasons. However, a mechanical one might be the most likely. You should have your starter motor replaced by a mechanic if that happens.
Another delicate part is the transmission mount. Despite its size, the transmission mount plays a significant role in maintaining a decent performance for your ride.
The transmission mount is likely lost when you hear a clunk noise when accelerating from your engine like it is about to break out. The noise, in this case, appears when metal crashes into metal.
Sometimes when you go over a bump, your transmission mount can also make that thump noise when driving. The reason behind it is the shifting in your transmission while driving.
This indicates that your transmission mount is heavily affected, and you should go to a mechanic as soon as possible to avoid dangers.
Car Makes Thump Sound When Slowing Down
If your car makes a thump sound when driving slow, it’s likely because of a warped rotor. In this case, the unusual sound will possibly originate from your front wheel as you brake to slow down the vehicle.
Brake rotors are metal discs positioned behind the vehicle’s wheels. Together with the calipers and brake pads, they create friction to slow down the wheels as you brake.
Over time, this friction will accumulate damages and cause warped brake rotors as natural wear and tear.
When the surface is damaged and uneven, it can cause annoying sounds and make the performance of your brake diminish.
Other signs can tell whether your brake is going bad. The most obvious one is a decreased performance of your braking, i.e., the car takes longer and farther to slow down or stop.
Or, in some cases, you can experience a pulsating steering wheel when you try to brake. Besides a thump, it can also feature annoying sounds like squeaking or screeching.
When you notice any of the above symptoms, you should have a mechanic check your brake and replace the brake rotors if possible.
Car Thumps When Driving
Provided that your vehicle doesn’t thump when accelerating or when braking but rather when driving, a possible reason is worn tires.
Your tires can give off a strange thumping sound when they experience irregular or uneven wear or shifted belts.
In this case, the noise comes from outside of the car and depending on the position of the affected tire, it can appear in either the front or back of the vehicle.
You should regularly check the pressure and tread levels of your tires.
If you try to keep riding with a thumping and damaged tire, you are wasting more fuel and making the vehicle drag more, and you have a lot of significant risks and dangers on the road.
In other cases, if your tires are normal, you should check the suspension components. In this situation, the sound will likely be located in the vehicle’s front.
As your suspension mount experiences wear and tear over time, they allow the struts to vibrate against the car’s chassis, creating a rattling or thumping sound and a bumpier ride.
When this happens, you should bring your car to a repair shop and have a professional look at it to replace any worn-out components to ensure safety and performance.
Common Causes Of A Thumping Noise When Driving
This part will go into further details as to why your car can make a thumping noise and which components are at fault.
Tire Problems
As we discussed below, tire problems are the easiest to notice and fix an annoying sound. But worn-out tires are not the only thing that can cause such trouble. Sometimes, the type of tires you are using might be the root.
It is especially true if your tires are new and haven’t been damaged yet. Tires with steel belts are very tough and durable, but they can be very noisy, and that’s normal.
Belts with different materials such as fiberglass and synthetic are much quieter. Fortunately, in this case, the sound doesn’t indicate trouble.
Also, don’t forget to check for your tires’ balance and alignment regularly.
Worn-out Struts And Shocks
Struts and shocks are some of the suspension components. The struts are located in the front wheels, while the shocks are located in the back wheel to absorb shock when driving.
If they are damaged and worn out over time, they will vibrate against the vehicle’s body, and you will need to replace them.
Broken Starter Motor
A defective starter motor mount will likely make noise when you start or accelerate your vehicle. The mount connects the chassis and the engine to absorb vibrations.
If it is damaged, the vibration will impair the body and generate a thumping noise when the engine starts.
Check to see whether you have to replace it regularly.
Other Brake Problems
Damaged brake components will create a sound when the vehicle slows down. But other than worn-out brake rotors, some parts are also at risk.
If you have worn-out brake pads, the metal components inside the pad will make contact with the rotors to create sound.
Luckily, this is not highly complex trouble, and you can easily replace it with a new one.
Bad Transmission
In this case, the vehicle will make a sound in the front when you are downshifting without braking. To test it, go to a quiet place with smooth roads and test for yourself if this is the case.
If the sound persists, you should check all the vehicle’s fluids, including ATF fluid and power steering fluid. And remember not to overfill it.
Wheel Bearing Problems
A bad wheel bearing will often lead to an inconsistent thumping sound when your vehicle goes into a curve and changes in speed. Sometimes, it will be very loud and other times much quieter.
An excellent way to diagnose yourself is to use a dial indicator with your wheels to measure the bearing’s play. If it exceeds .005, you should replace it right away. You can also go to a mechanic to deal with the problem.
Exhaust System Problems
If you stop the car without turning off the engine and hear a thumping sound in your exhaust, it could be a sign of problems related to the exhaust system.
The thumping sound from the exhaust is the common case, actually. But when you notice it’s louder than usual or produce no sound at all, it’s time to worry about the exhaust system.
This time, you will have to visit a repair shop and check it out before it leaks more toxic air to the environment and affects the vehicle’s performance.
Worn-out CV Joint
The component transfers stable power between the transmission and the wheels when you are driving. If it is damaged, it can cause a click and thump sound.
The early sign of bad CV joints is oil leaking inside the wheel rim. So if you spot this symptom, give your buddy a visit to the nearest auto shop for help.
Why Is My Car Making A Thudding Noise?
Besides a thumping noise, sometimes you can also hear a thudding noise from your vehicle. If that’s the case, you should check for low tire pressure or wheel alignment.
Either will cause fuel drainage, and your ride’s performance will suffer.
Conclusion
That’s everything you need to know if your car makes a thumping noise when driving. Overall, the problems only affect the easy-to-replace car components and are nothing to be scared out of your wits.
Nevertheless, you should pay attention to minor signs like this to maintain an excellent condition for your vehicles.