A flexible exhaust connector is a small but essential part of the exhaust system. Choosing the right flexible connector will also protect other exhaust components, such as the catalyst, from too fast wear out and reduce the amount of vibrations generated by the engine.
What is a flexible exhaust connector and how does it work?
The flexible exhaust connector is also called the vibration damper. It consists of four layers – two main bellows, outer braid and inner braid or pipe. The main bellows are corrugated tubes that reduce vibrations. A purpose of the braid is to increase flexibility and protect against weather conditions.
The method of assembling the inner braid into the bellows is important. A good quality flexible connector ensures a constant flue gas flow diameter.
The vibrations that the motor produces are transferred to the following components of the exhaust system. The flexible connector is installed behind the exhaust manifold. It is a shield that eliminates some of the vibrations. As a result, further elements – catalyst, silencers and exhaust pipe – are no longer exposed to such high stresses.
What material is the flexible exhaust pipe connector made of?
The flexible connector should be made of high quality SS 304 steel or higher. This guarantees good resistance to vibrations, but also corrosion and high flue gas temperatures (approx. 600-700 °C). This element of the exhaust system will survive up to 4-5 years without any problems.
There are also worse products on the market. Those with a smaller admixture of nickel are more stainless, but also stiffer and less tolerant of vibrations. Another problem with low-grade steel is the quick rusting process. The lifetime of such flexible connector may be even not longer than 3-4 months, especially in countries with variable weather, i.e. where there is heavy rain or snow.
Why is a flexible exhaust pipe connector so important?
As long as the exhaust connector is well-matched and works, everything is fine. Trouble starts when it begins to fail. There may be several reasons:
- it is incorrectly mounted
- made of poor steel, so too stiff
- it just used up
At low-quality steel connectors, a frequent problem is shrinking internal braid, which can reduce the light flow by up to 30%. This, in turn, has an effect on less efficient exhaust emissions, and hence a decrease in engine power.
The shaky motor, which is not suppressed by the elastic connector, transfers the entire load to all parts of the exhaust system. The worst situation is for a catalyst that is not designed for these operating conditions and is closest to the exhaust manifold. As a consequence, the lifetime of the catalyst is reduced, but also silencers, exhaust pipes, handles and hangers.
Last but not least, the acoustics of the car are equally important. One of the first symptoms of abrasion of a flexible connector is knocking under the chassis. This has influence on lower driving comfort and lower driver concentration. And the damage can be done by accident – by hooking a high curb or a stone or gravel spatter from the tires.
Directional or typical connection?
There are two-way and unidirectional connections. The former operate independently, in which direction they are mounted. A directional connectors have a blue border on the exhaust side. The difference is in the arrangement of braid and parameters.
What to look for when replacing the flexible exhaust pipe connector?
If we purchase the connector on our own, we must first measure the length and diameter of the vibration damper. It is best if the measurement is very precise, eg with a caliper. It would be an unpleasant surprise if the new connector turned out to be a few millimeters too short.
Fortunately, this element of the exhaust system is most often universal and fits every brand and model. The length of the flexible connector varies between 60 and 350 mm and the diameter between 38 and 90 mm.
Of course, dedicated vibration dampers are produced for individual brands. We would install special elements in Citroen C5, Audi A4, A3 and A6, Volkswagen Passat and Golf, Renault Laguna, Megane, Thalia and Scenic, Fiat Palio, Punto, Seicento and Siena, Seat Cordoba, Leon, Toledo and Ibiza, Skoda Octavia, Volvo S40 and V40. They have a flange, on the one hand, which eases assembly.
The DPF filter has been introduced for cars with a diesel engine and some with a petrol engine to protect the environment from solid particles’ emission. Unburnt ash and soot are deposited in the filter channels, and cleaner exhaust gases get out. However, the filter capacity is limited, and after about 300-600 kilometres travelled, the filter clogs up. When forced firing is not enough, the car owner faces a classic dilemma — replacement or regeneration of the DPF filter?
Automatic combustion and fuel additives
Typically, the pressure gauge in the filter signals to the computer the need for self-firing. The combustion chamber gets a larger dose of fuel, and thanks to the higher temperature of gases (about 550 deg. C) the soot is burned out. Some advanced DPF filters with an additional injector also dispense fuel directly to the filter. Unfortunately, oil ash does not burn out, and for self-cleaning to occur, you need to drive at a higher minimum speed for 10-15 minutes.
What if we only travel in the urban cycle and do not achieve the speed needed for automatic burnout? There are preparations for filtering on the market. They can be poured directly into the tank or into the filter, after removing the lambda probe. They lower the temperature needed to burn soot. As a result, more solid particles are burnt. Manufacturers recommend using them every three thousand kilometres. However, this is not a permanent solution, but only an inevitable postponement. In the first place, the control lamp on the dashboard will light up. It must not be ignored.
Types of DPF filter regeneration
There are several types of restoring the filter to the correct capacity. Mechanical and chemical regenerations are the most popular and relatively cheapest compared to the necessity of exchange. In addition to forced firing, it is always necessary to dismantle the filter during a renovation. The service technician also evaluates whether the structure of the insert is not damaged, for example, cracked or fused.
There are services that offer forced firing, but the filter cannot be too full. An external computer connected to the engine maintains a speed of about 3,000 revolutions per minute for half an hour. In the event of failure, additional restorative preparations may be used. After this treatment, it is necessary to change the oil. The cost of this regeneration is about 150-200 PLN plus a new oil. It should be remembered that forced combustion does not remove ashes.
Thermal and ultrasonic regeneration
Here it is necessary to disassemble the filter. In thermal regeneration, the cut cartridge is subjected to high temperature — about 700 °C for about 8 to 48 hours. When the process is finished, the filter is welded.
Services using the second method let special chemicals into the cartridge or immerse the filter in water. Under the influence of ultrasound, air bubbles or preparations dissolve impurities. The regeneration process is the longest possible and takes about 12-24 hours. The cost of the service is about PLN 400-500. These methods are not very popular and reputable.
Chemical regeneration / rinsing with water / hydrodynamic method
Using the product for cleaning fireplaces and ordinary pressure washer, we can at best damage the DPF filter. It is better to go to a station where regeneration takes place on a similar basis but under strictly controlled conditions. The clogged filter is placed in a special device connected to the measuring apparatus. Water with a special washing gel is passed through the ceramic insert, first the reverse and then in the direction of the exhaust gas flow. A pressure of the liquid is strictly controlled. The clean filter is subjected to drying at a temperature of about 90°C and cooling. A cost of hydrodynamic regeneration is about PLN 400-500 and gives the best results. Rinsing with water removes approx. 98% of sediments and lasts about an hour.
Replacing the DPF filter
Sometimes regeneration does not fulfil its task or the filter is damaged. Then you have to replace it. A home budget before a large expense can protect the purchase of a replacement filter from a reputable company, instead of a much more expensive original part. The cost of the replacement depends on the brand and model, usually fluctuating between PLN 1,500 and 2,500. We should pass it around 100-150 thousand kilometres without problems.
Buying a used filter always carries a risk. We do not know who and how he cared for it, what course it actually has or is well cleaned. Deciding on the original part for the exhaust system, however, you have to reckon with the costs. Here the price list also depends on the brand — the cheapest about 500-700 PLN, Fiat about 2,500 PLN, Ford, Mercedes about 5000 PLN, BMW, Volvo about 6000 PLN, VW Golf about 8000 PLN, Mitsubishi about 10,000 PLN. Therefore, it seems reasonable to buy a new replacement part, from a reputable company. With the new filter, the car will travel about 150-300 thousand kilometres without problems.
Replacement or regeneration of the DPF filter
Regeneration is much cheaper than replacing the DPF filter. Using the hydrodynamic method of rinsing with water, we get the filter almost like a new one. Then the exchange will be necessary only in case of damage or melting of the cartridge.
Activities of environmental protection began to be undertaken in the United States in the 1960s. The first DPF filter was installed in 1985 in the American Mercedes W126. Unfortunately, the technology was not well-developed at that time, so after two years the idea was abandoned. The reasons were the low efficiency of filters and the frequent need for extra trips to burn soot. Today, technology has gone ahead. So how does the DPF filter work?
How does the DPF filter work?
The ideal situation is when the entire fuel dose is burned to give water vapour and carbon dioxide. However, a car is not a laboratory. So by-products of combustion are carbon soot (carbon oxides) and coal itself, solid particles, nitrogen oxides and hydrocarbons. They used to go directly to the environment. Today they have to go through the DPF filter or re-burn thanks to the ERG valve and then filtering.
The filter itself looks like a catalyst and is part of the exhaust system. At the inlet and outlet there is a special pressure gauge. On the basis of the pressure difference, it assesses the degree of clogging of the filter and, if necessary, starts the self-firing process. Depending on the driving style, this usually takes about 300-600 km. Then it is necessary to drive at a constant speed of 60-80 km / h for about 10-15 minutes.
Inside the particle filter has a ceramic cartridge. It consists of a series of channels. They are alternately closed from the inlet or outlet side. The flue goes to them, the soot and combustion products settle, and the cleaner exhaust gases pass to the neighbouring channels and travel towards the exhaust pipe.
In which cars do not the DPF filter exist?
In the past, no particulate filter was installed or it was done at the owner’s request. All cars produced after 2010 must comply with Euro 5 standards, and thus have a filter. During the transitional period, lower standards, like Euro 4, were also acceptable.
From 2007 to city centres in Germany, and from 2015 in Austria, you can enter only with the “green sticker”, meaning the Euro 4 standard. For models that did not meet this standard, the solution was to install a DPF filter not integrated with the computer. It was cheaper to install, but it did not support automatic regeneration. As a result, after the clogging, the filter had to be replaced each time.
When buying a used car it is worth paying attention to the approval plate. The number in the square determines the degree of pollutant emission. The value 0.5 means the existence of a filter, value 1.2 and more – no filter. Then you should be aware that adding this element will be necessary.
What is the difference between DPF and FAP?
There are several different types of particulate filters. In older models, a simplified DPF filter was fitted, which was not integrated with the car’s electronics. It had to be replaced after each clogging. This is an expensive and troublesome solution in the long run, but it raises the norm from Euro 3 to Euro 4.
The DPF named also as dry filter is the most popular one. We meet him mainly in German brands. It is located near the exhaust manifold. There is a high temperature there, and a slightly larger portion of fuel fed in the exhalation phase is enough to burn soot.
In turn, French cars usually have a wet filter known also as FAP. A special liquid (Infineum or Eolys) is added to the filter, which reduces the temperature required for firing. As a result, self-regeneration is more efficient. In operation, this is the cheapest solution, although it is necessary to regularly refill the liquid. Corporations are slowly moving away from the concept of FAP filters. Eg Peugeot in the series with BlueHDi engines has already put on classic DPF filters.
There are also advanced diesel particulate filters with an additional injector. They can be found, for example, in Renault with a 1.5dCi engine or Toyota with a 2.2 D-CAT engine. At the right moment, a portion of the fuel is injected into the filter, which burns the excess soot and sediments.
Not only the diesel engine is fitted with an exhaust gas cleaning device. Cars fuelled with petrol with direct fuel injection increasingly have a GPF filter. This is due to a much higher ignition temperature. Is this a good way to develop gasoline engines? Opinions are divided.
Is a particle filter needed?
American cities in the 1950s, in the era of massive development and popularity of cars, faced a real environmental problem that was being solved. Similar efforts were made by European constructors. The result is ERG valves and particulate filters that significantly reduce the emission of harmful substances into the air. Thanks to the technological progress and a wide range of parts and exhaust fitting accessories, we have significantly reduced the impact of exhaust gases on our planet. Restrictive standards are not only a whim of officials, but a real need. Therefore, even people with older specimens should consider installing a DPF.
Every owner of a diesel car wonders how to extend the life of a DPF filter. Its replacement is very expensive. If you decided to regenerate, you wish the intervals between regenerations are as long as possible. That’s why it’s worth using a few tricks.
The greatest effect on the lifetime of the DPF filter
The purpose of the DPF filter is to purify exhaust fumes from soot and other deposits before leaving the exhaust system. Therefore, the quality of exhaust gases has the greatest impact on the clogging of the DPF filter. The more we help the combustion process, the cleaner the exhaust will go to the exhaust system, and the DPF filter will last longer.
The right car oil
An oil itself is not the most dangerous, but the ennobles added to it. On the one hand they protect the engine, but always some part of the oil gets into the combustion chamber. In cars with a DPF filter it is advisable to use low ash oils. Thanks to them, less sulphate ash is formed and the filter clogs more slowly.
And remember, the soot can burn in the process of automatic filter cleaning but the ash settles in it permanently. Exemplary markings on car oil’s packages are: LowSASP, DPF, Class C in ACEA classification (C1 and C4 is low SAPS, and C2, C3 and C5 is medium SAPS) or Emmision System Protection. There are also MB 229.51, 507.00 and BMW-LongLife-04 standards.
Passing the oil into the exhaust system through a damaged or worn turbocharger is suicide for a DPF filter. The oil creates a so baked residue in the ceramic cartridge that it can not be removed. Therefore, it is not worth saving on this element and replace it or regenerate at the first incorrect symptoms or every 100,000 km.
What’s more, these are elements dependent on each other. A clogged DPF filter causes a higher load on the turbocharger. In addition, extinguishing the car during the after-burning of the filter results in the depletion of additional fuel to the engine oil. Such diluted oil badly affects the engine seals, and especially on the sensitive turbocharger. Worse lubrication can lead to damage.
If you have noticed a cloud of soot that exits the exhaust system every time you press the gas and the engine has lost power, you may suspect an Exhaust Gas Recirculation valve malfunction. Normally, it is responsible for reducing the concentration of nitrogen oxides in the exhaust. It diverts exhaust gases back to the combustion chamber, where a repeated chemical reaction reduces their content. Only then the exhaust go to the exhaust system. A worn valve immobilized in the open position by the carbon deposits causes the inferior air mixture to flow into the combustion chamber at all times. Thus, the combustion temperature decreases. Reaction products have more soot, which did not have a chance to burn out. As a consequence, the DPF filter is blocked faster than it has the possibility of self-cleaning.
The car can be tuned cheaply or well. During cheap tuning is used poor quality boxes that generate large amounts of soot in the exhaust. On the other hand professional services focus on quality and after the assembly perform smoke tests.
Injectors are responsible for the uniform spraying of fuel and the quality of its combustion. If they are consumed, the combustion process is not going well and huge amounts of soot are produced. The filter needs chemical regeneration every month or two. Unfortunately, it is not a cheap item to replace or repair fuel injectors, sometimes it is even several thousand zlotys.
Low impact on the service life of the DPF filter
There are also two other ways for a longer DPF life, although they have less impact. First of all, you should take care of the good quality fuel and the regular replacement of the air filter.
Fuel of uncertain quality
What we pour into the tank has an effect on what goes out of the exhaust system. By using oil purchased non-official, from truck drivers or agricultural machinery, you can quickly clog the filter. Modern filters require fuel with specific parameters and composition, e.g. sulphur content. Another option is to use fuel additives, eg Liqui Moly diesel-partiklefilter Schutz.
The air filter should be replaced at every periodic inspection, especially since it is not expensive investment. In case of a blocked filter, less air comes to the intake system. This, in turn, affects the combustion process and influences increased formation of soot.
How to extend the life of the DPF filter
Keeping the car in good condition should guard against failures and extend the life of the DPF filter. You should remember that the exhaust system has many components and exhaust accessories that are interrelated. As soon as possible, removing the defect of one element will prevent accelerated destruction of the others.
The exhaust system is an important component of the construction of cars. It increases the comfort of travelling, and at the same time allows the engine to work properly and contributes to reducing the number of harmful substances emitted by the car. The main elements of a car exhaust system are exhaust manifold, muffler, exhaust pipe and exhaust fitting accessories. At present, the exhaust system has been additionally equipped with a catalytic converter with a lambda probe. Modern diesel engines have also a DPF filter. These basic elements consist of many different elements necessary in the construction of the exhaust system. Without them this system could not work.
The main elements of the car exhaust system
The exhaust manifold is the first important element. It is attached directly to the engine block and responsible for collecting exhaust gases from several adjacent engine cylinders. It leads them to a common pipe. To this wire can be connected with turbocharger drive nozzle in turbocharged engines.
The oxygen sensor is a sensor that measures the oxygen content in the exhaust gas. It is placed in the exhaust system before and after the catalytic converter. It’s task is to examine the composition of exhaust gases. Based on the lambda sensor readings, the microprocessor controls the fuel dose in such a way that the exhaust composition is as close as possible to the optimal one.
The catalyst is another element of the exhaust system. It uses chemical reactions to reduce harmful gases by converting them into carbon dioxide, water vapour and pure nitrogen.
Further elements of the exhaust system are mufflers connected to the catalyst by pipelines. Usually, there is one or two silencers in a row. One of them is an absorption silencer responsible for suppressing high frequencies of sound (above 500 Hz). Therefore, it is not sufficient and it is used together with other silencers in a combined silencer, which is responsible for attenuation of sound at a wide frequency range. It is also possible to use other combinations of these two types of mufflers.
In modern Diesel engines, there is also a DPF filter. It served for capture harmful particles found in the exhaust. These particles are deposited in the filter, and thanks to the self-cleaning process, they are automatically removed from it. The self-cleaning of the filter consists in applying an extra dose of fuel at the moment of expansion. This causes the temperature in the filter to raise enough to burn the accumulated soot.
Mounting elements of the car’s exhaust system and exhaust fitting accessories
The most important assembly and exhaust fitting accessories are rubber hangers, gaskets and rings, metal fasteners, springs, clamps, bolts and nuts, flexible connectors, flange joints and repair elements. There are many exhaust elements depending on the brand of cars, trucks, or other vehicles, such as excavators, ploughs, building machines, etc.
The most important tasks of the exhaust system
The most important tasks of the exhaust system are:
- flue gas discharge to a place where it can be discharged to the atmosphere in the least disruptive way for the driver and passengers,
- reduction of noise generated during flue gas discharge,
- flue gas cleaning to a form in which the content of toxic components is allowed by law,
- enabling the most efficient engine work in the whole range of loads,
- ensuring minimum flue gas resistance, enabling maximum engine power,
- guaranteeing the highest possible temperature of the fumes through minimal thermal radiation.
Flue gas discharge and noise reduction are tasks that have been in force since the very beginning of vehicle construction. Other tasks appeared gradually as automotive technology developed and engine performance increased. On the other hand the introduction of more and more stricter regulations in the scope of environmental protection against pollution contained in car exhausts was not without significance.
Durability and failure rate of the exhaust system
The exhaust system is part of the car’s construction, which does not require service during the entire period of its durability. On the other words there is also no specific time to replace the exhaust system. Reason is a system whose durability depends on the environmental conditions of its operation.
The symptoms of exhaust system damage are usually the louder running of the engine or the knocking under the vehicle. This second symptom may indicate broken holders or damage to the catalyst. In some cases, it is also possible for the smell of exhaust gases to appear inside the car. These defects can be easily noticed by the driver. It should be repaired as soon as possible.
Repairing the exhaust system usually means replacing a damaged component with a new one. It is important to use only approved components and exhaust fitting accessories. Using components that are not homologized can cause:
- bad noise suppression,
- higher fuel consumption,
- excessive emissions of toxic gases,
- damage to the catalyst or even the engine.
Elements of a car exhaust system
The car exhaust system consists of many parts. Starting with main ones and finishing on minor (but not less important) ones, like exhaust fitting accessories. Only all parts together allow the proper and safe car usage for people and the environment. Regardless of whether you drive a car, truck or another vehicle, you should remember that if you notice or hear the wrong work of the system, you should respond quickly.
An exhaust system is responsible for removing fumes from an engine. Nowadays exhaust systems are more complex than they used to be. There are some exhaust system spare parts that are especially susceptible to damage. But should they be always replaced by original parts? Exhaust fitting accessories can be successfully delivered by local manufacturers.
How a car exhaust system works
The work of the exhaust system is mainly combustion of fuel. A car moves on thanks to a series of explosions. The exhaust system is responsible for reducing noise, fuel gas discharge and fumes cleaning. It is built mainly from such exhaust fitting accessories like pipes, sensors and filters. The only visible part of the exhaust system is an exhaust pipe – the rest is hidden deep inside a car.
The most important exhaust system spare parts
A typical exhaust system consists of a silencer, an exhaust manifold and a catalytic converter.
The silencer is built from pipes joined to the engine by a connecting pipe. In some cars, there can be more than one silencer. It absorbs and reduces noise resulting from engine operation.
The exhaust manifold resembles a system of pipes joined together. It is linked with the engine. It collects fumes from cylinders to transport them to the catalytic converter. Inside exhaust manifold, a lambda probe can be placed, also called a lambda sensor. It is responsible for an exhaust composition test.
The main task of a catalytic converter is to neutralize exhaust. Thanks to its work fumes emitted from the exhaust pipe are not harmful to the environment.
What can go wrong?
The most obvious problems resulting from exhaust system failure are noise and an intense smell of fumes. But there may also be invisible defects. That is what makes regular technical crucial.
Moisture has a negative effect on silencers. In result, they usually rust and pierce. The damaged silencer can be repaired, for instance, welded, or exchanged. But not only a silencer pipe can be destroyed, but also clamps and rubber elements holding the silencer at the chassis. In that case, the silencer pipe bumps against the chassis and sometimes it can even break away.
High temperatures may cause the exhaust manifold to crack. It can be manifested by a sighing sound heard when the engine enters high revolutions. Such damages can be successfully repaired but in some cases, the exhaust manifold exchange may be necessary. Another frequent fault is a leak between the exhaust manifold and the rest of the exhaust system.
The catalytic converter is mainly exposed to pollution. It can be also damaged by using low-quality fuel. Soot particles that settle on the converter can be easily removed by dynamic car driving. But if it does not work, the device should be replaced by a new one.
Where to repair an exhaust system?
It is often said that a car should be repaired only in an authorized car service. Maybe it is a better solution for brand-new cars. Their owners have then a guarantee that a damaged part is exchanged for equally valuable one and that it is done in a fully professionally way.
What can stop you from such a solution are high costs. Unfortunately, the authorized car service repairs are really expensive. And in some cases, it is not reasonable to overpay. With older cars, it is much better to get a working vehicle with cheaper equivalents. Unoriginal exhaust fitting accessories can prove to be equally good. That is why we sometimes decide to choose a garage instead of an authorized car service.
Cheaper exhaust system components – what can be replaced?
The answer is simple: everything! Starting from bolts, ending with catalytic converters. However, there is always a group of people who are afraid of replacing more complex components with its cheaper equivalents. But even them cannot deny that there are some spare parts that may be produced by anyone and still be of sufficient quality.
Let’s take for example clamps or gaskets. Clamps are metal rings with screws. They can be used to join together two ends of a pipe. They are also useful when changing the refrigerant fluid. Clamps are a very good solution when replacing a fuel filter. In a garage or in a private car, they appear to be quite a desirable tool. And it is quite obvious that producing a good clamp is not very complicated. Any reliable manufacturer can deliver such a spare part at a reasonable price.
Gaskets are responsible for tightness of more complex devices especially at points where two elements are joint together. They can be found for example in the engine. They are particularly vulnerable to the influence of extremely high temperatures and continuous pressure changes. And it is sometimes better to have such a gasket made by a small experienced manufacturer (especially by someone who is aware of how the car engine works) than by a big firm. Why? Because he knows where main problems can appear and how to avoid them, in brief: what a perfect gasket means.
Undoubtedly, all so-called auxiliary spare parts do not need to be bought at an authorized car service. Every proven car mechanic can recommend us the manufacturer of bolts, rings or pipe connectors. And we can also check his reliability by installing in our own car a more complex spare part. Why not try one of his DPF filters? If everything goes right, we can gain a supplier of high-quality economical solutions.