Your internal-combustion engine is very loud. Along with lots of power it produces when burning fuel, it creates dozens of sound waves that leave the combustion chamber together with exhaust gases through the exhaust system. On their way, they pass through a special echo chamber, which helps for canceling specific sound frequencies before the exhaust gases enter the muffler. This echo chamber is usually called a resonator or a pre-muffler.
While the resonator and the muffler do a similar job, helping for creating a pleasing exhaust note, they serve different purposes and do their job in a different way. The resonator causes sound waves to cancel each other without reducing the volume of exhaust gases, whereas the muffler does lower the noise and absorb sound waves. The muffler features a set of tubes and baffles and/or sound-absorbing materials, such as fiberglass or a similar one. When exhaust gases pass through the muffler they change their note, making your vehicle sound quieter.
There are two main types of resonators found in today’s vehicles. It can be a standing-along part or come as a part of a muffler assembly. The majority of modern cars utilize the second type of resonators, however, there are also lots of vehicles with an individual resonator that is placed somewhere between a catalytic converter and a muffler. Whichever the type your vehicle is equipped with, your resonator is crucial for your driving comfort and smooth engine operation. Its failure may not only make your driving unpleasant, but also cause a number of engine-related problems. Here are the most common of them:
Poor fuel economy and performance
A clogged or damaged resonator can block or restrict exhaust flow through the exhaust system. This will cause the engine to work harder, resulting in reduced engine performance and fuel efficiency.
Illuminated check engine light
If the engine control unit detects any performance problems caused by a bad resonator, it will turn on the check engine light.
Inability to start the engine and stalling
A faulty resonator can create a lot of back pressure that will not allow the pistons to move. As a result, the engine will stall or won’t start at all.
A damaged or leaking resonator can allow exhaust gases to leave the exhaust system through a hole or crack in the resonator. If so, you’ll hear a high-frequency buzzing sound.
Exhaust gas smell in the cabin
A hole in the resonator can lead to an exhaust gas leak. That’s why some exhaust gases can enter the cabin, so you’ll notice a bad odor.
Made from steel alloys, resonators are prone to rusting both from the outside and inside. The latter is caused by corrosive exhaust byproducts, while the outside rusting is a result of dust, rainwater, snow, road salt, etc. Depending on the climate you live in and the material your resonator is made from, it can last from a couple of years to 7 or 8 years. This is much longer than the lifetime of resonators produced in1960s and 1970s, which were made from simple steel. However, modern resonators also need to be replaced from time to time.
Other common resonator failures are worn-out or damaged rubber hangers and mounts. Such components should be checked on a regular basis to prevent severe damage to other exhaust system components.
Resonator troubleshooting and replacement
Most resonators are not repairable, which is why they must be replaced if they’re damaged or worn-out. Before replacing your resonator, a thorough diagnosis is recommended to avoid unnecessary expenses. Besides, the entire exhaust system should be inspected for signs of corrosion and damage to prevent unplanned repairs in the nearest future.
Depending on the design of your resonator, some cutting or welding may be required. That’s why replacing a bad resonator should be left to a professional.