New cars are so quiet, you can sneak up on somebody, and they may not know you’re behind them. Manufacturers have always been innovating modern ways to make cars quieter to improve vehicle comfort.
Mufflers, resonators, catalytic converters and new Gas Particulate Filters (GPF or OPF) have all helped to make cars quieter. The engine also has mounts and seals that keep it quiet.
But we have come across or have cars that are louder than they’re supposed to be. This could be as a result of one or more of these parts failing. It could also be because some parts meant to keep the car quiet have been stolen or changed
Here are 10 reasons why some cars are louder than others.
Table of Contents
1. Damaged Exhaust/Exhaust Leak
Your car will be louder if the exhaust is damaged or has a leak in it. This can occur because the underside of the vehicle has hit something, puncturing the exhaust. Rust may have also eaten up the exhaust and caused it to separate.
A leaking or damaged exhaust causes a loud rumble under your car. The faster you drive, the louder it gets, and it is not a pleasant sound. Exhaust leaks are mostly found directly under your vehicle.
An exhaust with this issue is very dangerous. Hot fumes exit the end of your exhaust where there’s nothing to get damaged. If this exhaust exits from under your car, the hot fumes will melt and damage parts under your vehicle.
Remember, your fuel tank is also under the vehicle. If it gets hit with these hot fumes after an extended period, it could cause a fire. So, it is advised to fix or change a leaking or damaged exhaust as soon as possible.
2. Bad or Stolen Catalytic Converter
Catalytic converters or cats help prevent harmful exhausts gases from exiting your vehicle. They also help keep your car quiet. If they get stolen or go bad, your car becomes louder.
Catalytic converters are essential components of your exhaust system. They rarely go bad but if they do, they can function properly thus making your vehicle louder.
Stolen catalytic converters are more common in this case. Now, you would ask why would anyone steal a catalytic converter?
Well, the components inside are rare earth metals that react with poisonous exhaust fumes, making them harmless. This makes them expensive and valuable.
The first-gen Toyota Prius has been a huge target for cat theft. Selling one of these old cats can fetch between $1,500 and $2,000. Once this is taken off, the noiseless Toyota Prius sounds like a working tractor.
3. Resonator Delete
Resonators don’t make your car quieter. Instead, they help smoothen the frequency of sound coming from your engine. This can be the difference between a smooth and rough-sounding engine.
The sound of a vehicle can be altered by simply changing or removing the resonator. Most sounds from the engine are a mix of combustion (explosion) and rubbing metal parts, which are not pleasant to the ear. Resonators will help smoothen this sound (frequency) giving the engine a calm note.
Like every part of a vehicle, if the resonator goes bad, then the sound changes to a louder, raspy exhaust note.
4. Failing Muffler
Mufflers or silencers are found at the end of your vehicle and control how loud your vehicle would be. This is part of your exhaust system is usually a large piece with various components inside that regulate how loud or soft the car is.
All vehicles must have mufflers, it is required by law for all new vehicles. A good muffler or bad muffler makes a huge difference with the sound you hear at the back of your vehicle.
This is a relatively minor issue compared to other parts close to the engine. Although, consequences could be increased exhaust fumes and possibly affect your gas mileage.
5. Broken Seals or Gaskets
Seals are found on connecting parts of your exhaust. The primary function of a seal is to stop things from escaping from air-tight areas. If any one of these seals is broken, the exhaust may rattle and become louder.
Seals are found everywhere in your vehicle, your door jams, engine compartments, and your exhaust system. When broken, they can’t perform their simple task.
In the case of your exhaust, the seals help reduce eliminate noise from connected parts of your exhaust. If broken your car becomes louder similar to a leak in your exhaust system.
6. Bad Spark Plugs
Bad spark plugs mean your engine does not fire correctly. When the engine doesn’t fire correctly, there’s an imbalance. The engine gives a different sound and in severe cases, the engine can even rock back and forth.
Without spark plugs your engine will not start, it can start on bad spark plugs but will not run smoothly. The sound the car emits will be like a sputtering sound like the engine wants to go off eventually.
In some cases, they may not even be bad. Just covered with oil or carbon. A simple clean or replacement of all spark plugs will solve this problem.
7. Bad Engine Mounts
Engines have mounts that cushion the harsh and loud vibrations coming from your engine. Bad engine mounts will transfer these loud vibrations into the vehicle, making it very uncomfortable.
Mounts have a layer of rubber on them, and just like any rubber part, they wear and break over time. Rubber mount issues are usually common in older cars. But they can be found in newer vehicles if not mounted properly.
Bad mounts transfer the excess noise and vibration to be transferred into the cabin. This is a big problem as it can only be fixed by lifting the engine, which involves a professional. Leaving an issue to linger so long will eventually lead to damages in other parts of the engine.
Luckily, engine mounts are relatively inexpensive. The only real cost comes with labor.
Also read: 15 Cars that NEVER Rust (100% Galvanised)
8. Bad Bearings
Bearings are parts that aid the rotation of moving parts. They are found inside your engine and help transfer motion and reduce friction. Lubrication is also necessary if bearings are to perform their job optimally.
Wheels also have bearings, and so does your driveshaft. If any of the bearings in your car goes bad, it creates a constant grinding sound when in motion. This can increase friction (stiffness) and wear the affected cause uneven wear to the affected parts.
Prolonged use of the vehicle in this state will eventually destroy the affected parts. If your engine bearing is affected, it needs to be replaced as soon as possible.
9. Faulty Transmission
Transmissions have gears and moving metal parts inside them. Transmissions do go bad and when they do the noise is unbearable, and you hear every noise emitted inside the vehicle.
Signs of bad transmissions include:
- Burning Smell.
- Slipping Gears.
- Dragging Clutch.
- Leaking Fluid.
- Check Engine Light.
- Grinding or Shaking
- Humming Sounds
The sounds and smells made by the transmission can be heard from outside and inside the vehicle. Changing gears is noisy, you hear the clutch, and the shaking is transferred into the vehicle.
The most annoying of all is the constant hum or whine you hear as if you’re reversing. Transmission fixes are expensive, a simple fix can cost $300-$1,400. Replacing one starts at around $2,000.
10. Louder Performance Exhaust
Some cars are louder simply because they have a performance exhaust. This replaces the restrictive parts with free-flowing parts, making the engine note louder.
These exhausts are normally found in sports and performance cars. They help the car extract more power from the engine and in most cases sound better. An example is a V8 engine found in Ferraris, which sounds really good.
Some exhausts make the car sound better than stock, while others are just plain noisy. A loud exhaust on a 4-cylinder SUV will just make a lot of noise without really going fast.
Is it Illegal to Drive a Loud Car?
In some states in the US and some countries around the world, driving a loud car is illegal. There are laws that cars have to follow, in this case, it’s the decibel law. If a car’s sound is above the legal decibel reading for a state or country, it is deemed illegal.
Even if your car comes from the factory that way, if it exceeds the required decibel reading it is illegal.
Even in performance cars, manufacturers make sure they remain quiet when necessary. Every car has to abide by the noise laws imposed on each state.
Cars are quieter in Europe compared to North America, as the noise laws there a stricter. Breaking this law will lead to a fine.
In California, the decibel limit is 95, these laws are mostly enforced on newer cars. Older cars generally exceed this, but the requirements were different when they were made.