If you’ve driven your car for a long time, you probably know what it usually sounds like and can spot something odd. Rattling noises when driving on dirt roads, accelerating or even starting the engine tell you something is wrong. The muffler is often blamed for the strange noises. This article explains what’s going on with your muffler and if it’s responsible for these noises.
Why do I need a silencer?
A car’s exhaust system begins with the exhaust manifold, which carries combustion by-products to the tailpipe. The manifold consists of a catalytic converter, a resonator and a muffler (the order may differ depending on the car. Sometimes the resonator comes after the car muffler). The catalytic converter helps reduce the toxicity of exhaust gases. The resonator or middle silencer dampens the first pressure and sound wave of the engine and cools the exhaust. The main silencer is a system of reflectors and absorbers to reduce engine noise. Most countries have strict standards for the noise level produced by a vehicle, so driving without a muffler is often illegal. The car muffler also reduces vibrations caused by the pressure of sound waves.
Is the noise actually an exhaust rattle?
All elements of the exhaust system are simply plugged together and attached to the floor with clamps and screws. In a perfect world, they should be aligned and held firmly in place. The exhaust system is unprotected from below. That means contact with road chemicals in winter, bumps and rock chips on country roads, temperature differences and constant vibration all gradually degrading it over time. The older the car, the more attention you should pay to the exhaust system and its background noise.
Metallic rattling can be caused by the elements being misaligned along the pipe and hitting each other or the bottom of the car. Loose or corroded part struts can cause noise. If something rattles under the car or the noise comes from the tailpipe or somewhere under the car, the muffler is not necessarily the cause.
The noise could also be a sign of a more serious problem, such as leaks in the exhaust system, meaning gases are not being properly routed away from the car and can even partially seep into the saloon.
What is causing this noise?
The silencer resembles a large can, which consists of numerous baffles and/or perforated pipes inside. These are all traps for sound waves to be broken down and smothered. If an internal element or part of it collapses and falls apart, the parts can become stuck in the chamber and cause grinding, clanking or rattling noises. The resonator is made of ceramic. When shattered, the shards get stuck in the tubes and disrupt gas flow, causing rattling and buzzing. This problem is quite common since the muffler is an element that works under constant pressure.
Long vibration wears out the baffles and they are constantly being corroded as the exhaust gases condense and moisture is present. On most cars, the elements of the exhaust system are made of aluminized or stainless steel, but not necessarily inside the muffler: this is where manufacturers save money. You often hear from a car owner that the muffler mufflers have rusted through, so in most cases the entire element needs to be replaced.
What to do?
A regular check of the exhaust system should be part of your car maintenance routine, at least at the scheduled technical inspections. If you hear strange noises, you must do this immediately.
You can do the initial visual inspection yourself – all you need is a buck – get under the body and inspect the entire exhaust line – if anything is loose, looks damaged or is rusty there could be a problem that needs servicing. It’s worth driving past a gas station even if you don’t see anything. They conduct a detailed diagnosis, especially if you suspect that the muffler or some other element inside is damaged.
In most cases, this diagnosis is free because you have to pay for the repair anyway. Often tightening a few bolts and replacing a corroded shackle is all it takes to fix the vibrating parts, but here’s a general rule – the sooner you tackle the problem, the fewer headaches it will cause you. A small problem with the muffler that you ignore for a long time can cause more and more vibration and lead to total failure of that part.