Why is my exhaust loud all of a sudden?

How often have you been woken up from a nice night’s sleep or a relaxing nap by the sound of a noisy muffler blaring down the street? Or do you hear noises within your car but not directly from the engine? Both situations point to a possible problem with the exhaust system.

What is the exhaust system?

The exhaust system keeps passengers safe, helps the engine function, and reduces noise. You’ll only find them on gas-powered vehicles. Electric vehicles (EVs) don’t have them because they don’t have an engine.

By funnelling exhaust fumes created by the engine along your vehicle and out the tailpipe, passengers in the vehicle don’t breathe in the fumes.

Venting these emissions also helps your engine perform more efficiently. Some systems can create too much back pressure, which robs your engine of some of its power.

Furthermore, an exhaust system is designed to deaden the noise caused by exhausting fumes. Remember, noise is created by moving air, so fumes being pushed through a pipe will cause noise. The only problem is that this noise can come from any number of components in your exhaust system, so let’s review them.

Your exhaust system: what each part does

1. Exhaust ports: burned gases leave the engine through these ports and travel to the exhaust manifold.
2. Exhaust manifold: the burned gases continue travelling through the manifold, which pushes the gas into the rest of the exhaust system.
3. Exhaust pipes: these pipes connect several parts of the exhaust system, namely, the manifold, muffler, converter, and resonator.
4. Catalytic converter: this piece is attached to the pipe just before the muffler. It cleans exhaust gases as part of a vehicle’s emissions control protocol.
5. Muffler: as the name suggests, this muffles noise while still allowing for exhaust to vent out the tailpipe.
6. Resonator: essentially a mini-muffler; you’ll find this on more expensive cars.
7. Tailpipe: the last piece of the exhaust system.

There are two components that are located along the full system:

1. Hangers: these components suspend the exhaust system all the way from the engine to the tailpipe. This allows the components to expand and contract as needed, and they also contribute to sound deadening.
2. Heat shields: found on newer vehicles, they shield parts of the vehicle’s undercarriage from the heat created by the exhaust system.

Causes of a noisy exhaust system

A noisy exhaust system should be taken care of by a professional unless you’re an experienced DIYer. Dangers of doing it yourself include breathing in noxious fumes and burning yourself.

Noise in an exhaust system generally means something is affecting the pathway of the exhaust emissions from the engine to the tailpipe. We’ll look at a few common causes here.

Leaks along the exhaust system

Perhaps the most common cause is a leak in the system—there’s a hole in the bucket, so to speak. Rust and corrosion, regular wear, and damage from the road can also lead to leaks.

Damage to components

Damage to any component will also cause noise. Loose parts, for example, can cause rattling. If your muffler is damaged, your car will become one of the noisiest on the street.

Damage can happen from winter driving, moisture accumulation, and impacts.

What an automotive technician does

An automotive technician will take several steps to properly inspect your exhaust system and find the cause of the noise:

• Check for emissions, such as nitrogen oxides, carbon monoxide and carbon dioxide, free oxygen, and unburned hydrocarbons.
• Inspect the system for damaged parts and replace them.
• Test for blockages by using either a backpressure test or an engine vacuum.
• Ensure the catalytic converter is working.
• Inspect fuel control and oxygen sensors.

An expert at your nearest NAPA AUTOPRO service centre will be happy to answer your questions about your noisy exhaust system.

To read more about the exhaust system, follow the link below.

Muffler or Exhaust? – NAPA AUTOPRO

Photo: iStock-2152673049