The exhaust system of modern vehicles not only reliably discharges the exhaust gases, but also dampens the sound. For this purpose, several silencers are integrated into the exhaust system. Since the mufflers under the vehicle floor are exposed to high loads, they often become defective after a few years. In this guide, you will learn how the exhaust system of a car is constructed and what you can do if a silencer is defective.

Structure and function – how the car exhaust is constructed

Today, the exhaust systems of modern vehicles consist of numerous components, which are summarised under the term exhaust. The exhaust system begins in the engine compartment, where the exhaust gases leave the combustion engine. The manifold, through which the outflowing exhaust gas can be quickly discharged, is directly connected to the engine block.

Depending on the manufacturer and vehicle model, a Y-pipe or a flexible pipe follows behind the manifold as part of the exhaust system. After this, the exhaust gas usually passes through the catalytic converter, which in modern vehicles provides after-treatment of the exhaust gas. The catalytic converter can effectively reduce pollutant emissions. Modern diesels have a particle filter that reduces the emission of soot.

Rear silencer and central silencer reduce exhaust noise

On its way to the rear of the vehicle, the exhaust stream usually passes through several more metres of exhaust pipe as well as a series of silencers. These reduce the exhaust noise that is produced when all internal combustion engines are running. Only a few cars today still have a pre-silencer. As a rule, these are older vehicles.

In modern vehicles, the catalytic converter is usually followed by the central silencer. This is usually designed as an absorption silencer and breaks up the sound waves. Finally, the rear silencer, also called a muffler, follows at the rear of the vehicle. Such a rear silencer is often designed as a combination of a reflective silencer and an absorptive silencer.

The rear silencer usually carries the tailpipes or the single tailpipe of the vehicle. It is exposed to particular loads due to its position in the rear area under the vehicle floor. Therefore, the rear silencer causes problems more often than other parts of the exhaust system.

Typical symptoms of defective silencers

If a silencer of the exhaust system is defective, this becomes noticeable through various symptoms. Often there is a noise nuisance due to the broken exhaust. Therefore, the defective component should be replaced with a suitable replacement as soon as possible.

• Car causes more noise
• Exhaust gas leakage under the car
• Loss of power when accelerating
• Visible damage to the exhaust pipe

These are the consequences of a defective silencer

Since there is no damping of the exhaust noise with a defective muffler, the car causes more noise. Due to the unusual noises from the exhaust system area, many drivers first become aware of the broken exhaust.

If the centre silencer or rear silencer is defective, exhaust gases may also escape under the vehicle floor. Exhaust gases can then enter the vehicle interior through open side windows, for example. Since the exhaust system is a complex and coordinated system, a defect can even lead to a loss of engine power.

Visually visible damage to the exhaust is also a clear sign of the defect. If the silencer is damaged, there may also be a problem with the TÜV sticker in Germany. If the component is defective, the car will fail the main inspection. This is another reason why damage to the exhaust should always be repaired.

3 common causes of a defective exhaust pipe

• Material ageing: The material of the exhaust system is subject to constant ageing when the car is in operation. This is due to the heat of the exhaust gases and the constant changes in temperature from hot to cold.
• Road salt: In many regions, the use of road salt on the roads is common in winter. What is good for driving safety turns out to be a disadvantage for the exhaust. The road salt attacks the surface of parts of the exhaust system and promotes rust.
• Short trips: If drivers often use their vehicles for short trips, this can also shorten the service life of the exhaust. Since components such as the muffler do not heat up sufficiently, condensation accumulates there. This leads to damage such as rust from the inside.

Repairing the silencer on the car

The silencers of the exhaust system are exposed to great stress. Not surprisingly, they wear out quickly, so that replacement with new parts is due. The rear silencer is often the first to be defective. At the same time, the rear silencer is particularly easy to replace. Expert car mechanics therefore often change the muffler themselves.

Changing the end top in 5 steps

1. Jacking up the car: To be able to carry out repairs on the exhaust, the car should be safely jacked up. This is best done with ramps or a lifting platform.
2. Detach the rear silencer: To replace the rear silencer, the old component must be removed. Most rear silencers are connected to the exhaust system by means of a screw connection. In most cases a clamp has to be loosened, in a few cases the muffler has to be cut off with a saw or grinder.
3. Unhook the muffler: Once the muffler has been detached, it only hangs on the vehicle floor by means of muffler rubbers. The component can now be unhooked and simply put aside. The transition to the rest of the exhaust should be checked and cleaned with a wire brush.
4. Fit the new muffler: After dismantling the defective silencer, the new silencer can be fitted. To do this, the replacement part is first compared with the old rear silencer. If it matches the old component, it is hung under the car with new exhaust rubbers and inserted into the exhaust pipe.
5. Connect the exhaust: The last step in the repair is to align and connect the muffler. For this, screwing on the clamp is sufficient for many vehicles. Since the old clamps are often completely rusted, a new part should be used. If, on the other hand, the exhaust was welded, a new weld seam must be made at the connection to the muffler.

Repair the silencer or weld it?

The car’s muffler is one of the parts of the exhaust system most frequently affected by a defect. Holes or cracks often appear in the centre of the muffler, but also at the inlet and outlet. If these parts of the exhaust are defective, repair with an exhaust kit or welding is rarely worthwhile. Often the exhaust component is already so worn that it breaks down again directly in another place.

How much does it cost to repair the exhaust?

The price for an exhaust system repair depends on various factors, such as the manufacturer of the car and the model. It also depends on whether only parts of the exhaust are replaced or whether a complete exhaust replacement is carried out.

Often, it is sufficient to replace the sound-absorbing components of the exhaust system so that the exhaust is tight again. At Autoteile24 you will find a large selection of suitable new and used parts for the exhaust. Repairs to the exhaust system can often be carried out more cheaply.

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