Emissions text only.docx

**General Standard Work Practices** Safety does not only relate to the vehicle that is being repaired. Consideration must also be given to the safety of all others in the vicinity of the work being performed, even if those people are not in any way involve in the task being performed. Before start...

**General Standard Work Practices** Safety does not only relate to the vehicle that is being repaired. Consideration must also be given to the safety of all others in the vicinity of the work being performed, even if those people are not in any way involve in the task being performed. Before starting work on a vehicle, make sure that you are aware of the safety aspects of the work area and ensure that the work area is free from obstructions. Any spillage of fluid must be cleaned up immediately and in the appropriate manner. Hazard identification and risk assessments are to be performed prior to starting work. Hazard identification is to include - Health and safety hazards that pose a risk to the health and safety of people. - Hazards that pose a risk to the environment and the flora and fauna of the area or elsewhere. - Hazards that pose a risk of damage to machines, equipment, buildings, etc. **Safety** All operating vehicle engines produce poisonous or harmful gasses. Ensure that when operating a vehicle's engine that there is sufficient air flow to maintain a safe breathable working atmosphere. Be aware the carbon dioxide is heavier than air and will collect in low places. Standards are designed for the protection of everybody. Failure to comply to these standards may result in injury or loss of life and leave individuals open to litigation. Who is responsible? The person working on the vehicle is responsible for ensuring that the vehicle is safe. If the vehicle is not safe, it should not be driven. Working On Vehicles Some of the many safety features to be considered when working on vehicles are as follows: - Appropriate protective clothing and safety gear must always be worn before working on a vehicle along with the correct tools and repair equipment. - A vehicle should always be placed on a flat and even surface before starting work. The park braking system should be applied and the wheels should be chocked to prevent vehicle movement. - Any time that a vehicle is raised above the ground, safety stands suited to the weight of the vehicle should be placed under the vehicle in the appropriate support positions. If suitable stands are not available, it is not safe to work on the vehicle. - If components are being removed from or repaired on the vehicle, make sure that the vehicle is appropriately disabled and tagged accordingly, to prevent accidental starting. - Ensure that any components being repaired or replaced on the vehicle are the correct ones for the job and that repair procedures are carried out in accordance with manufacturers specifications and meet the requirements of design standards. - When dealing with compressed air, whether it be as part of the task being performed or as workshop air, avoid contact with the skin and be careful of particles that may be carried in the air. - Ensure that all tools and equipment used during the task is checked for serviceability and suitability of the task. Always check and clean tools and equipment for serviceability at the end of each task. Report and tag out exceptions. - Make sure that all adjustments and torque values are accurately adhered to ensure correct and safe vehicle operation once the task is completed **Heavy vehicle emissions and their effects on the environment and health** **The combustion process.** All internal and external combustion engines produce pollutants regardless of their size and configuration. Most of the fuels used in the operation of internal combustion engines are hydrocarbon fuels derived from fossil fuels (crude oil). Gas turbines used in power generation are usually powered by natural gasses which are also hydrocarbon fuels. Another type of hydrocarbon fuel used for power generation is coal. Coal is used as a heating energy source in an external combustion engine to create steam under pressure that drives a steam turbine. In a perfect world hydrocarbon fuels (HCs) are burned with oxygen (O~2~) from the atmosphere to produce energy and waste products Carbon Dioxide (CO~2~) and water (H~2~O). HC + O~2~ CO~2~ + H~2~O Carbon Dioxide (CO~2~) is a greenhouse gas that is contributing to global warming. Unfortunately, the combustion is rarely perfect, and the hydrocarbon fuels are not usually completely pure. Incomplete combustion generates additional pollutants Carbon Monoxide and unburnt Hydrocarbons. Many hydrocarbon fuels also contain impurities such as sulphur which also combine with oxygen during the combustion process to for sulphur dioxide (SO~2~) which reacts with water to produce sulphur dioxide. High temperature combustion in an oxygen rich environment, such as a diesel engine, form Nitrogen Oxides in the combustion chamber as the oxygen reacts with the atmospheric nitrogen contained in the charge air. The following are the most common pollutants emitted from the combustion process Carbon Monoxide (CO) Nitrogen Oxides (NO~X~) Hydrocarbons (HC) Sulphur Dioxide Carbon Dioxide Ozone Particulate Matter **Pollutants produced by combustion** **Carbon Monoxide (CO)** What is carbon monoxide? Carbon monoxide (CO) is a colourless, odorless gas. It results from the incomplete combustion of carbon-containing fuels such as natural gas, gasoline, or wood, and is emitted by a wide variety of combustion sources, including motor vehicles, power plants, wildfires, and incinerators. Nationally and, particularly in urban areas, the majority of outdoor CO emissions to ambient air come from internal combustion engines used in mobile sources. Carbon monoxide can also be formed through photochemical reactions in the atmosphere from methane and non-methane hydrocarbons, other volatile organic hydrocarbons in the atmosphere, and organic molecules in surface waters and soils. There are also a number of indoor sources of CO that contribute to total exposure. Air quality regulators are concerned about air pollutants which may reasonably be anticipated to endanger public health and welfare. There is substantial evidence that CO can adversely affect health, participate in atmospheric chemical reactions that result in formation of ozone air pollution, and contribute to climate change. Health effects Carbon monoxide is harmful because it binds to hemoglobin in the blood, reducing the ability of blood to carry oxygen. This interferes with oxygen delivery to the body's organs. The most common effects of CO exposure are fatigue, headaches, confusion, and dizziness due to inadequate oxygen delivery to the brain. For people with cardiovascular disease, short-term CO exposure can further reduce their body's already compromised ability to respond to the increased oxygen demands of exercise, exertion, or stress. Inadequate oxygen delivery to the heart muscle leads to chest pain and decreased exercise tolerance. Unborn babies whose mothers experience high levels of CO exposure during pregnancy are at risk of adverse developmental effects. Unborn babies, infants, elderly people, and people with anemia or with a history of heart or respiratory disease are most likely to experience health effects with exposure to elevated levels of CO. Environmental effects CO contributes indirectly to climate change because it participates in chemical reactions in the atmosphere that produce ozone, which is a climate change gas. CO also has a weak direct effect on climate. For these reasons, CO is classified as a short-lived climate forcing agent, prompting CO emission reductions to be considered as a possible strategy to mitigate effects of global warming. **Nitrogen Oxides (NOx)** What are Nitrogen Oxides The term nitrogen oxides (NOx) describes a mixture of nitric oxide (NO) and nitrogen dioxide (NO2), which are gases produced from natural sources, motor vehicles and other fuel burning processes. Nitric oxide is colourless and is oxidised in the atmosphere to form nitrogen dioxide. Nitrogen dioxide has an odour, and is an acidic and highly corrosive gas that can affect our health and environment. Nitrogen oxides are critical components of photochemical smog. They produce the yellowish-brown colour of the smog. In poorly ventilated situations, indoor domestic appliances such as gas stoves and gas or wood heaters can be significant sources of nitrogen oxides. Health effects Nitrogen oxides (NOx) react to form smog and acid rain. NOx reacts with ammonia, moisture and other compounds to form nitric acid vapour and related particles. The impacts of NOx on human health include damage to the lung tissue, breathing and respiratory problems. Nitric oxide (NO) is not considered to be hazardous to health at typical ambient conditions. However, excess nitric oxide and its products may cause respiratory ailments, hematologic side effects, metabolic disorders, low blood pressure, nausea, vomiting and diarrhoea. Nitrogen dioxide (NO2) at high concentrations causes inflammation of the airways. Breathing in high levels of NO2 can increase the likelihood of respiratory problems: wheezing, coughing, colds, flu and bronchitis. People with asthma are prone to have more intense attacks. Prolonged exposure to high levels of NO2 can cause irreversible damages to the respiratory system. Environmental effects Nitrogen Oxides can have harmful effects on our environment and on us. The roots and leaves of agricultural crops can be damaged if there are high levels of oxides of nitrogen in the air, water or soil, and the plants may not even survive. This leads to farmers having a poorer harvest. Nitrogen dioxide also contributes to smog. High levels of oxides of nitrogen can produce acid rain which affects groundwater and soil and in turn, damages our environment and everything in it. **Hydrocarbons** What are Hydrocarbons Hydrocarbons are organic compounds consisting only of hydrogen and carbon atoms, found in fossil fuels like crude oil, natural gas and coal. They are grouped into five main families or homologous series (alkanes, alkenes, alkynes, cycloalkanes, alkadiene). The hydrocarbons within a homologous series share a general formula, chemical and physical properties. The most recognizable hydrocarbons are those from the alkene family, like methane, ethane, propane and butane, which share a simple construction with carbon-carbon single bonds. Hydrocarbon emissions from vehicles is generally in the form of incomplete combustion. Health Effects Inhalation or aspiration may lead to an asthma-like reactive airway syndrome as well as a chemical pneumonitis. Hydrocarbon has low surface tension and a low viscosity, therefore it penetrates deep into the lungs. This leads to a severe necrotizing pneumonia. Symptoms typically present as a cough and/or shortness of breath. Central Nervous System effects can be both short and long-term. In an acute setting, generalized depression may be seen with slurred speech, disorientation, headache, dizziness, ataxia, syncope, nausea, hallucination, agitation, violent behaviour, and seizure activity. Prolonged exposures, such as seen in workplace exposures, also can result in neuropathy, reduction in brain size, and encephalopathy. Research is showing the exposure to unburnt hydrocarbons may effect heart beat rhythm Skin exposure may cause mild irritation, or with prolonged exposure, chemical burns ranging from superficial to full thickness burns. Full thickness burns may lead to systemic symptoms. Skin irritation found periorally is known as "glue sniffer\'s rash." Skin lesions may present as bullae or blistering. Other skin manifestations include jaundice and/or mucous membrane irritation. Environmental Effects Unburnt hydrocarbons very harmful when released to the atmosphere in their unburnt form. They are toxic, carcinogenic molecules that are found in engine exhausts, as well as evaporating petroleum and gasses. Heavier forms can contaminate soil and groundwater. Methane, the hydrocarbon most frequently discussed in this context, is a more powerful heat-trapping greenhouse gas than carbon dioxide (CO~2~), so when it leaks into the atmosphere unburnt, it contributes more to climate change than the carbon dioxide produced by burning it. **Sulphur Dioxide** What is Sulphur Dioxide Sulphur is a chemical found in various forms naturally in the earth's crust. Crude oil also contains sulphur that is usually bonded to the carbon atoms. Sulphur is difficult to completely remove during the refining process. As a result, most fossil fuels contain a certain quantity of sulphur. Sulphur dioxide (SO~2~) is a colourless gas with a sharp, irritating odour. It is produced by burning fossil fuels and by the smelting of mineral ores that contain sulphur. Erupting volcanoes can be a significant natural source of sulphur dioxide emissions. Health Effects Sulphur dioxide affects the respiratory system, particularly lung function, and can irritate the Sulphur dioxide irritates the respiratory tract and increases the risk of tract infections. It causes coughing, mucus secretion and aggravates conditions such as asthma and chronic bronchitis. Environmental effects When sulphur dioxide combines with water and air, it forms sulphuric acid, which is the main component of acid rain. Acid rain can cause deforestation acidify waterways to the detriment of aquatic life corrode building materials and paints. Sulphur dioxide has a pungent odour that is sometimes referred to as a rotten egg smell. **Carbon Dioxide** What is Carbon Dioxide Carbon dioxide, (CO~2~), a colourless gas having a faint sharp odour and a sour taste. It is one of the most important greenhouse gases linked to global warming, but it is a minor component of Earth's atmosphere (about 3 volumes in 10,000), formed in combustion of carbon-containing materials, in fermentation, and in respiration of animals and employed by plants in the photosynthesis of carbohydrates. The presence of the gas in the atmosphere keeps some of the radiant energy received by Earth from being returned to space, thus producing the so-called greenhouse effect. Health Effects CO~2~ is considered to be minimally toxic by inhalation. The primary health effects caused by CO~2~ are the result of its behavior as a simple asphyxiant. A simple asphyxiant is a gas which reduces or displaces the normal oxygen in breathing air. Symptoms of mild CO~2~ exposure may include headache and drowsiness. At higher levels, rapid breathing, confusion, increased cardiac output, elevated blood pressure and increased arrhythmias may occur. Breathing oxygen depleted air caused by extreme CO~2~ concentrations can lead to death by suffocation. Environmental Effects Carbon dioxide has both beneficial and detrimental environmental effects, both to do with the greenhouse effect. The greenhouse effect is where greenhouses gases, such as CO2, absorb the sun's solar energy and traps heat within the Earth's atmosphere, creating a climate habitable for humans and other species. During the day, the sun sends solar energy to the earth, warming up our oceans and land. At night, the Earth releases this energy back into the air to escape through the Earth's atmosphere. Greenhouse gases trap some of this escaping heat, keeping our plant at a temperature perfect for living in. The greenhouse effect keeps our planet at a balmy 15°C -- a temperature ideal for humans and other species to live and thrive in. Without gases such as carbon dioxide to create the greenhouse effect, the Earth's average temperature would be -18°C. The world would be covered in ice, and life wouldn't be as we know it. The greenhouse effect is a good thing when it's in balance. The problem is that carbon dioxide is tipping the greenhouse effect out of balance. Before the 1700s, the Earth was happily regulating the greenhouse effect -- absorbing solar energy and emitting greenhouse gases at a steady rate. Then, the Industrial Revolution happened. Emissions of greenhouse gases, predominantly carbon dioxide, have been steadily increasing and kicking the greenhouse effect out of balance. What does this mean? Essentially, there are too many greenhouse gases absorbing the sun's energy, which means our planet is slowly warming up. We know this as climate change. And there doesn't appear to be an end in sight. Between 2000 and 2020, the Earth's emissions more than quadrupled from the previous decade. **Ozone** What is Ozone Ozone (O~3~) is a highly reactive gas composed of three oxygen atoms. It is both a natural and a man-made product that occurs in the Earth\'s upper atmosphere (the stratosphere) and lower atmosphere (the troposphere). Stratospheric Ozone helps protect life on earth, whereas Tropospheric (ground level) Ozone is detrimental to human health and the health of all other life on earth. Stratospheric ozone is formed naturally through the interaction of solar ultraviolet (UV) radiation with molecular oxygen (O2). The \"ozone layer,\" approximately 6 through 30 miles above the Earth\'s surface, reduces the amount of harmful UV radiation reaching the Earth\'s surface. Tropospheric or ground-level ozone -- what we breathe -- is formed primarily from photochemical reactions between two major classes of air pollutants, volatile organic compounds (VOC) and nitrogen oxides (NOx), both by-products of the combustion process. Health Effects Breathing ground-level ozone can trigger a variety of health problems including chest pain, coughing, throat irritation, and congestion. It can worsen bronchitis, emphysema, and asthma. Ozone also can reduce lung function and inflame the lining of the lungs. Repeated exposure may permanently scar lung tissue. Healthy people also experience difficulty breathing when exposed to ozone pollution. Because ozone can mostly effectively form in warm and sunny weather, anyone who spends time outdoors in the summer may be affected, particularly children, outdoor workers, and people exercising. Some people who don\'t fall into any of these categories may also find themselves sensitive to ozone. Environmental Effects Ozone damages vegetation by entering microscopic leaf openings called stomata and oxidizing (burning) plant tissue during respiration. This damages the plant leaves, interfering with the photosynthesis process and reducing the amount of carbon dioxide the plants can process and release as oxygen. Elevated levels of ozone can also lead to reduced agricultural crop and commercial forest yields, reduced growth and survivability of tree seedlings, and increased susceptibility to diseases, pests, and other stresses such as harsh weather. Ozone can cause substantial damage to a variety of materials such as rubber, plastics, fabrics, paint and metals. Exposure to ozone progressively damages both the functional and aesthetic qualities of materials and products, and shortens their life spans. Damage from ozone exposure can result in significant economic losses as a result of the increased costs of maintenance, upkeep and replacement of these materials. **Particulate Matter** What is Particulate Matter Particulate matter, also known as particle pollution or PM, is a term that describes extremely small solid particles and liquid droplets suspended in air. Particulate matter can be made up of a variety of components including nitrates, sulphates, organic chemicals, metals, soil or dust particles, and allergens (such as fragments of pollen or mould spores). Particle pollution mainly comes from motor vehicles, wood burning heaters and industry. During bushfires or dust storms, particle pollution can reach extremely high concentrations Diesel exhaust emissions contain a range of chemicals, gases and diesel particulate matter. Diesel particulate matter (DPM) is the solid part of the diesel exhaust. DPM comprises very small carbon particles that have absorbed layers of other materials. Diesel engine particulates are made of sub-micron (PM2.5) particles of diameters typically ranging from 30 to 500 nm (0.03-0.5 µm), with a maximum concentration between 100-200 nm (0.1-0.2 µm). Health Effects The size of particles affects their potential to cause health problems: PM10 (particles with a diameter of 10 micrometres or less): these particles are small enough to pass through the throat and nose and enter the lungs. Once inhaled, these particles can affect the heart and lungs and cause serious health effects. PM2.5 (particles with a diameter of 2.5 micrometres or less): these particles are so small they can get deep into the lungs and into the bloodstream. There is sufficient evidence that exposure to PM2.5 over long periods (years) can cause adverse health effects. Note that PM10 includes PM2.5. There are many health effects from exposure to particulate matter. Numerous studies have showed associations between exposure to particles and increased hospital admissions as well as death from heart or lung diseases. Despite extensive epidemiological research, there is currently no evidence of a threshold below which exposure to particulate matter does not cause any health effects. Health effects can occur after both short and long-term exposure to particulate matter. Short-term and long-term exposure is thought to have different mechanisms of effect. Short-term exposure appears to exacerbate pre-existing diseases while long-term exposure most likely causes disease and increases the rate of progression. Short-term exposure (hours to days) can lead to irritated eyes, nose and throat worsening asthma and lung diseases such as chronic bronchitis (also called chronic obstructive pulmonary disease or COPD). Long-term exposure (many years) can lead to: - reduced lung function - heart attacks and arrhythmias (irregular heart beat) in people with heart disease - increased rate of disease progression - increases in hospital admissions and premature death due to diseases of the respiratory and cardiovascular systems. Environmental Effects Particulate matter has been shown in many scientific studies to reduce visibility, and also to adversely affect climate, ecosystems and materials. PM, primarily PM2.5, affects visibility by altering the way light is absorbed and scattered in the atmosphere. With reference to climate change, some constituents of the ambient PM mixture promote climate warming (e.g., black carbon), while others have a cooling influence (e.g., nitrate and sulphate), and so ambient PM has both climate warming and cooling properties. PM can adversely affect ecosystems, including plants, soil and water through deposition of PM and its subsequent uptake by plants or its deposition into water where it can affect water quality and clarity. The metal and organic compounds in PM have the greatest potential to alter plant growth and yield. PM deposition on surfaces leads to soiling of materials. **Heavy vehicle emission control systems and components** There has been concern over the health and environmental effects of the pollutants from the combustion process for many years. The United Kingdom introduced the first clean air act in 1956 after it was determined that the fog that covered London in December 1952 was made more intense and more dangerous to health due to the level of coal smoke it contained. Since then, there has been a variety of clean air acts passed by various governments around the world in an attempt to reduce the harmful effects of pollutants created by the combustion process. Many of these acts relate to the pollutants emitted from internal combustion engines. Engine manufacturers have responded by designing various methods and devices that are built into the engines they manufacture to reduce the levels of pollutants from their engines to meet the emission standards that have been set by various governments. The most common of these emission control systems are: Closed Crankcase Ventilation Systems Operating engines, petrol, gas or diesel, produce blow-by. Blow-by is some of the compression and combustion gasses flowing pass the rings into the combustion chamber. Blow-by air consists mainly of unburned hydrocarbons but also contains Nitrous Oxides and Carbon Monoxide. These gasses mix with the oil mist and oil vapour to produce sludge and other lubricating oil contaminants that reduced the oil and engine life. They also pressurise the crankcase causing seals to leak. In the early 1930s, engine manufacturers began to use draft tube. Prior to the early 1960s, most vehicles used a draft tube arrangement to ventilate the crankcase of the engine. A draft tube consisted of a tube usually with one end fitted to an opening in the rocker cove that ran down to just below the bottom of the sump. The tube was fitted so that when the vehicle was moving, the air flow pasted the bottom of the tube would create a small vacuum that would "suck" the blow-by gasses into the atmosphere. A vent in the system, usually a vented oil filler cap, would allow air to enter the crankcase to help purge the blow-by gasses. Some industrial diesel engines still use draft tubes. The problem with draft tubes is that there was always some oil from the oil mist in the crankcase that was also picked up and ran down the draft tube as droplets and landed on the road. This cause most roads to be contaminated by oil, in particular, those roads with heavy traffic flow. This would lead to dangerous driving conditions, particularly when it rained. Some, but not all, vehicle used some form of oil separation system, such as a catch can to separate the oil from the blow-by gasses. These were not always successful. A further complication was that the breather usually had an oil coated wire mesh filter to prevent dust, dirt and other contaminants from entering the crankcase. This unit needed to be washed out with a solvent and re-oiled at regular intervals to continue to function correctly. A modification was made at some time during the 1950s to seal the engine and redirect the draft tube into the air cleaner. This would use the partial vacuum created by the air ducting to drag the blow-by gasses back through the intake system and be burned in the combustion chamber. This system still required a breather to operate. While this system was better than the draft tube, it still failed often and engine life and lubricating oil life was reduced. Positive Crankcase Ventilation (PCV) During the second world war (1939 to 1945)there became a requirement for tank engines to be sealed to prevent the entry of water as the tanks forded deep waterways. This is when the Positive Crankcase Ventilation (PCV) system was first used. It was not until the 1950s that it was determined that such a system could be used on cars to reduce Hydrocarbon emissions. In 1961, California regulations required that all new cars be sold with a PCV system, therefore representing the first implementation of a vehicle emissions control device. PCV valves were introduced into Australia in 1968 on a voluntary basis. They became mandatory as part of the Australian Design Rules in 1972. The PCV system requires a breather to function and, in many cases, this was still the oiled wire mesh oil filler cap. The system was changed not long after to seal the engine with a sealed oil filler cap and use filtered air from the air cleaner to operate as the breather. In the PVC system, the scavenging fresh air id drawn into the crankcase, either from the air filter or some other breather device. The PCV valve is usually filler to the rocker cover with a tube to the intake manifold, which is usually under a vacuum when the engine is running. The PCV valve controls the amount of blow-by entering the intake manifold always keeping the crankcase under a slight vacuum approximately -0.75kPa or -0.11PSI.  The table below shows the position of the PCV valve during vehicle operation The PCV valve will automatically close the intake manifold has a positive pressure such as a backfire incident or turbo charger pressure. In modern vehicles, faulty PCV valves can cause error codes to occur. The most common of these error codes is a MAF sensor fault due fuel trim codes not being correct for the MAF signal being sent. PCV valves come in many shapes and sizes as illustrated by the images below In most cases the valve is placed in the rocker cover with a tube connecting the valve to the inlet manifold The filtered air breather is usually also fitted to the rocker cover, but as far away from the valve as possible. In many V configurations, the breather line is fitted to the rocker cover of the opposite bank. Some manufactures, such as BMW, have designed their rocker covers so that the PCV assembly is built in. The assembly may have other items fitted such as a separator unit to remove oil from the crankcase gasses. Sometimes, these units are fitted with replaceable PCV valves, sometimes they are not. When it comes to turbocharged engines, a PCV valve system is not going to function under full load when maximum boost is created and there is positive pressure in the inlet manifold. When the engine is under full power is when the greatest blow-by occurs and crankcase ventilation is most needed. A modified system is required for a turbocharged petrol engine. A Pressure Regulating Valve (PRV) is used to control crankcase blow-by and basically replaces the PCV valve, though some manufacturers use a combination of both. The PRV system must also be equipped with an oil separator unit to remove any oil that may be picked up can be separated from the blow-by gasses and drained back into the sump. The oil separator units are sometimes part of a filter unit fitted under the rocker cover and requires servicing at regular intervals. Other separator units are built into the PRV assembly. The PRV generally consists of a spring loaded diaphragm in a housing with 2 ports, sometimes more. The top section of the diaphragm is open to the atmosphere. One port is connected to the crankcase and the other port is connected to the inlet manifold and the air ducting between the air filter and the turbo charger. If there is a MAF (Mass Airflow sensor) fitted, the outlet tube and valve is attached after the MAF sensor before the turbo charger. This eliminates the risk of oil entering the MAF sensor. There is a check valve at the end of the tube that enters the intake manifold, and another at the end of the tube that enters the intake air ducting. During normal operation with no boost pressure from the turbo charger, the intake manifold would be under a vacuum but there would be a higher pressure (though still a small partial vacuum) in the intake air ducting between the air filter and the turbo charger. This would cause the one way check valve at the intake air duct to close and the one way valve at the intake manifold to open. The blow-by pressure and spring pressure will open the valve and the blow-by gasses will flow to the intake manifold. As the intake manifold vacuum increases, the vacuum will pull towards the closed position. This will restrict the blow-by gas flow. A balance point should be reached where the crankcase will be under a small vacuum of between 76mm and 180mm of water which is about -0.75kPa to -1.75kPa. Note, 180mm of water is about 0.25psi. The blow-by gasses mix with the intake air and are burned in the combustion chamber. When the vehicle is under load and the turbo charger is pumping full boost, the intake manifold will be under pressure. At the same time, maximum air flow will be passing through the air cleaner. Under these conditions, there will be the maximum pressure drop across the air filter resulting in a vacuum between the air filter and the turbo charger. This pressure drop should not exceed -4kPa (405mm water) for a petrol engine. This vacuum will be sufficient to operate the Pressure Reducing Valve at the time it is most needed as the amount of blow-by is greatest under full load. The blow-by gasses mix with the intake air and are burned in the combustion chamber.  Diesel Engine Closed Crankcase Ventilation Diesel engines do not use a PCV valve for their positive crankcase ventilation system. As there is no restriction to the incoming air with most diesel engines, there is not enough vacuum developed in the intake manifold to operate a PCV valve. Many industrial diesel engines just vent the closed crankcase to the intake ducting between the air filter and the turbo charger Small high speed diesels and on highway truck are required to use a Closed Crankcase Ventilation system by legislation. These systems use a Crankcase Depression Regulator (CDR) valve. This system is very similar to the Closed Crankcase system used by the turbo charged petrol system and is plumbed in a very similar manner. The Crankcase Depression Regulator valve, used on diesel engines, and the Pressure Regulator Valve, used on turbo charged petrol engines, are almost identical in construction and operate in a very similar manner. The main difference being that the CDR can not have a connection to the intake manifold as most diesel engines do not develop any significant vacuum in the intake manifold The crank case ventilation system outlet pipe is usually vented between the air cleaner element and the intake manifold on a naturally aspirated engine, or the air cleaner and the intake side of the turbo charger on a turbo charged engine. Most systems have an oil separator to prevent the oil droplets that are carried by the blow-by gasses entering the intake side of the engine. However, not all engines used an oil separator which meant that oil did enter the intake system and created issues such as oil saturating the filter element etc.. Some owners of these types of vehicle fitted "Catch Can" systems to catch the oil prior to the blow-by gasses entering the intake system. Most catch cans do not drain back to the sump and need to be emptied of the captured oil on a regular basis. The system functions as there is a resistance to the flow of air through the air filter. This creates a low pressure (partial vacuum) between the air filter and inlet manifold for a naturally aspirated engine, or the air filter and the turbo charger on a turbocharged engine. If there is a MAF (Mass Airflow sensor) fitted, the outlet tube and valve is attached after the MAF sensor before the turbo charger. This eliminates the risk of oil entering the MAF sensor. The amount of air filter restriction at low engine speeds and load is not great, but as this also corresponds to low production of blow-by gasses, it is not an issue. As the engine speed and load increase, so does the pressure drop across the air filter. An increase in engine speed and load also increases the amount of blow-by produced. This increases the flow of blow-by gasses from the crankcase to the intake air, which is desirable. The pressure (is usually a low vacuum) of the blow-by gasses from the crankcase acting on the larger surface area of the CDR valve diaphragm will try to push the valve open, but the vacuum of the intake ducting acting on the smaller surface area of the CDR valve will try and close the valve. If the pressures in the crankcase and the intake ducting equalise, the valve will close. The increase of blow-by gasses in the crankcase will cause the pressure to rise and the CDR valve will open so that these gasses can be purged. **Testing and Diagnosing Faults in the Positive Crankcase Ventilation Systems** PCV Valve System What happens when the PCV valve is faulty? When the valve is faulty, or the hoses that feed the system are clogged, your car's performance can take a beating, engine components can corrode and oil can seep into the intake manifold. Fortunately, the PCV valve is not expensive, nor difficult to test, clean and replace. It should be routinely checked as part of a regular vehicle-maintenance schedule, together with the vacuum hose, clamp and hose connections. PCV valves usually fail either open or closed. One of the most obvious signs that your PCV valve needs to be replaced is excess oil consumption. If the valve gets stuck in the open position, excess vapours will be drawn from the crankcase, which results in your car burning more oil than normal. If the PCV valve is stuck closed, pressure will build up in the engine and oil leaks will usually result. Excessive amount of condensation in the crankcase can also occur. This is commonly seen during an oil change by milky deposits found on the oil fill cap or seen inside the oil fill hole. Although the internet abounds with articles that describe in some detail how one can test suspect PCV valves, the simple fact is that there are no reliable methods to test PCV valves in general or to test the calibration settings of any given PCV valve to ensure that it works. There are a couple of tests that can give an indication that PCV valve may not be working as it should. Test 1: Remove the PCV valve from the valve cover with the hose still attached. Then place your finger over the open end of the hose. If the valve's working well, you will feel strong suction. There may be a minor change in engine RPM. Try shaking the valve. If it's unobstructed, it should rattle. If it's fouled, the rattle will be indistinct or non-existent. This is not a definitive test as some PCV vales will not rattle no mater how hard they are shaken Remove the cap from the oil filler hole on the valve cover and place a stiff piece of paper over the opening. If your PCV valve is working properly, the paper should be sucked against the hole within seconds. There should not be enough vacuum to suck the stiff sheet of paper passed the oil filler hole. A manometer can be used to check the crankcase vacuum at the dip stick opening. There should be a vacuum of between 74 to 100mm of water. If the vacuum is to high, i.e greater than 100mm, then the PCV valve may be stuck open. If the valve is stuck open, it is usual to see oil in the intake manifold, especially where the pipework enters the manifold. Check the system breather. A blocked breather may also cause excessive vacuum to occur. If the manometer shows a positive reading, this could indicate that the PCV valve is stuck closed. This will usually create oil leaks and the build up of sludge inside the engine. Fuel dilution of the oil is also possible so smell the oil for fuel fumes. Check the end of the breather, there may be a build up of oil at that point. Make sure to complete system check before testing for blocked or split hoses, perished grommets and so on, anything that can cause an air leak. The system requires regular maintenance to keep it working correctly. Always check hoses and clamps at every service. PCV Valves should be replaced between 30,000km to 80,000km Pressure Regulation Valve System Turbocharged Petrol Engines - Discoloured exhaust gas that is white, black, or blue. - A check engine light warning. - Rough idling and acceleration. - Whistling or hissing noises from the engine. - Increased fuel consumption. - Misfiring. - Engine oil leaks. First check the hoses and clamps for splits, poor fittings and secure routing. With the engine running listen for the hissing sound of air leaking. A common fault with this system is the PRV diaphragm splitting and sucking air. Use a manometer to measure the crankcase vacuum. The dipstick tube is usually a good place to attach the manometer. A good reading is between 255 to 405 mm of water. A high reading could indicate that the PRV is not closing and excess vacuum is building in the crankcase. Insufficient vacuum may indicate that the PRV is blocked and not letting the blow-by gasses passed, or that the valve diaphragm is split and air is entering the system. Due to the entry of air into the system and the vehicle tending to run lean, a failure of this crankcase ventilation system can, and often does, activate the check engine warning light and display several fault codes usually associate with fuel trim values. Another common fault code that is commonly displayed is a MAF sensor fault. Crankcase Depression Regulator Valve System Diesel Engines The CDR valve is responsible for controlling the pressure/vacuum in the engine crankcase, and separating the oil mist from the air and returning the oil to the crankcase. When the pressure builds up because the CDR is stuck closed the crankcase pressure will increase, and could force oil past some gaskets and seals that could result in leakage. If the CDR is stuck open oil mist from the crankcase will be sucked into the engine and burned as fuel, however, it is heavier and thicker than diesel fuel and, having greater BTU output, causes excessive heat in the cylinder. After a period of time, cylinder and head temperatures will reach unacceptably high levels causing the head bolts to stretch and the head gasket to fail. A quick way to inspect the CDR valve is to remove the air cleaner assembly and look into the air intake with a flashlight. If engine oil is visible in the intake manifold, test crankcase pressures or replace the valve. If you\'re using a litre of oil every 1,500 km you might want to take a look at your CDR valve. The Crankcase Depression Regulator (CDR) Valve maintains crankcase pressure. Pressure must be regulated to prevent oil consumption through the intake system, and to prevent oil leaks due to excessive buildup of pressure. Control is accomplished by regulating the blow-by gases into the intake system to be reburned. Inside the CDR valve, a spring holds open a valve plate that connects to the CDR valve body with a flexible diaphragm. The valve plate is capable of restricting the outlet passage to the turbocharger air inlet duct when airflow pulls it closed against the force of the spring. Specifications Crankcase pressure at idle................. 0 to 25mm of water Crankcase pressure at 2000 RPM........... 50 to 125mm of water Crankcase Pressure Check 1\. Obtain a water manometer 2\. Bring the engine to operating temperature. 3\. Remove the oil dipstick and attach the hose of the water manometer, to the dipstick tube. 4\. Start the engine and observe the manometer at idle: - If the reading indicates that the crankcase pressure is 0 to 25mm of water go to step 5. - If the reading indicates that crankcase pressure is higher than 25mm of water, inspect the CDR valve and recheck crankcase pressure. (if the CDR valve is good check engine compression). 5\. Run the engine at 2,000 RPM, observing the manometer. - If the reading indicates crankcase pressure is in a negative state between 50 to 125mm of water, the system is OK. - If the reading indicates crankcase pressure is in a negative state greater than 125mm of water, replace the CDR valve and retest. - If the reading indicates crankcase pressure is in a positive state, review test and results of step 4.\" A positive reading could indicate that the separation filter is blocked, or there is a blockage in the system at some point. Check for a build up of sludge in the pipework and kinks in the pipework. Air leaks between the CRV valve and the intake ducting can also cause positive crankcase pressures. **Exhaust Gas Recirculation System** EGR systems have been used for many years in internal combustion engines, including gasoline- and diesel-powered engines. They\'re found in cars, trucks, buses, and other vehicles, and stationary engines like those used in power plants and factories. EGR is a proven way to reduce air pollution caused by transportation and industrial applications. This process dilutes the air and fuel mixture that enters the combustion chambers, which reduces the engine\'s peak combustion temperature. The lower temperature means less NOx is formed during combustion, resulting in fewer air-polluting emissions. There are also some drawbacks to consider. Notably, a lower- combustion temperature also means a less efficient and complete burn. As a result, some fuel doesn't burn completely, and ultimately comes out of the exhaust as particulate matter (PM). For this reason, most diesel applications that use EGR must also employ a DPF to capture the excess PM. EGR is also known to accelerate engine oil degradation and increase the concentration of contaminants such as soot in the oil. This soot loading can lead to the build-up of deposits on the engine\'s valves and other components, reducing its overall efficiency and lifespan. In diesel engines in particular, EGR systems come with serious drawbacks, one of which is a reduction in engine longevity. Additionally, EGR systems can decrease the overall power output of an engine, as the recirculated exhaust gas, by diluting the air and fuel mixture, reduces the amount of oxygen available for combustion. This can make the engine feel less powerful and responsive at times. In a typical automotive spark-ignited (SI) engine, 5% to 15% of the exhaust gas is routed back to the intake as EGR. Excessive EGR in poorly set up applications can cause misfires and partial burns. Since diesels always operate with excess air, they benefit (in terms of reduced NOx output) from EGR rates as high as 50%. However, a 50% EGR rate is only suitable when the diesel engine is at idle, since this is when there is otherwise a large excess of air. Depending on the system in which it is used, the design of the EGR valve may change. Often these design changes incorporate some of the system controls. Types of designs included positive backpressure, negative backpressure, ported and pulse-width modulation. Vacuum Operated EGR Valves Most early EGR valves were vacuum-operated. A vacuum diaphragm opened and closed a valve, allowing and cutting off exhaust flow. An early refinement was a temperature-controlled shut-off in the vacuum source. This kept the EGR valve from opening when the engine was too cool. The cool engine did not require EGR and cutting it off made the engine run smoother.  Positive Backpressure Vacuum EGR Valves The positive backpressure EGR valve has a bleed port and valve positioned in the center of the diaphragm. A light spring holds this bleed valve open, and an exhaust passage is connected from the lower end of the tapered valve through the stem to the bleed valve. When the engine is running, exhaust pressure is applied to the bleed valve. At low engine speeds, exhaust pressure is not high enough to close the bleed valve. If control vacuum is supplied to the diaphragm chamber, the vacuum is bled off through the bleed port and the valve remains closed. As engine and vehicle speed increase, the exhaust pressure also increases. Negative Backpressure Vacuum EGR Valves In a negative backpressure EGR valve, a normally closed bleed port is positioned in the center of the diaphragm. An exhaust passage is connected from the lower end of the tapered valve through the stem to the bleed valve. When the engine is running at lower speeds, there is a high-pressure pulse in the exhaust system. However, between these high-pressure pulses there are low-pressure pulses. As the engine speed increases, more cylinder firings occur in a given time and the high-pressure pulses become closer together in the exhaust system. At lower engine and vehicle speeds, the negative pulses in the exhaust system hold the bleed valve open. When vacuum from an external source is supplied to a negative backpressure EGR valve with the engine not running, the bleed port is closed and the vacuum should open the valve.  Over time, electrical EGR units have been introduced into late-model vehicles. The most common of the three electrical EGR valves is the digital EGR units. Digital Electric EGR Valve A digital EGR valve contains up to three electric solenoids that are operated directly by the PCM. Each solenoid contains a movable plunger with a tapered tip that seats in an orifice. When any solenoid is energized, the plunger is lifted, and exhaust gas is allowed to recirculate through the orifice into the intake manifold. The solenoids and orifices are different sizes. The PCM can operate one, two or three solenoids to supply the amount of exhaust recirculation required to provide control of NOx emissions. When testing a digital EGR valve, you can use a scan tool to activate the valve. The rpm should drop for each activation period. An EGR valve that's plugged or not working will show no change. Pulse-width Modulated Solenoid EGR Valve Another style is the linear EGR valve, which is basically a pulse-width modulated solenoid valve where the valve is spring-loaded closed. GM was the first to use these linear EGR valves. The computer varies the pulse-width command to the valve to control the amount of opening. A position sensor is integrated into the valve. The sensor generates a signal, very similar to a throttle position sensor to indicate to the computer exactly how open or closed the EGR valve is. This feedback signal allows the computer to more accurately control the amount of EGR flow. Stepper Motor EGR Valve You also will encounter a stepper motor EGR valve, which is designed to work very similarly to GM idle air control motors that have been around for a long time. Here, the valve has two separate sets of coil windings. The PCM sends alternate, coordinated pulses to each winding to "step" the motor open or closed in small increments. Unlike all other vacuum and electrical design EGR valves, stepper-type EGR valves remain in the last commanded position even when disconnected electrically. They do not "spring" closed when disconnected. Diagnosis and testing When diagnosis of a negative backpressure EGR valve is needed, you must bring the engine up to normal operating temperatures. With the ignition off, disconnect the vacuum hose from the EGR valve and connect a hand-held vacuum pump to the fitting on the valve. Supply 18 inches of vacuum to the EGR valve and vacuum should hold steady for 25 seconds. If the valve does not open or cannot hold the vacuum, it must be replaced. If the valve holds steady, start the engine and the vacuum should drop to zero and the valve should close. When diagnosis of a positive backpressure EGR valve is needed, the same basic test is used like with the negative type but with opposite results. When the engine is idling, apply vacuum to the EGR valve and you should not be able to build up a vacuum in the valve and the EGR valve should not open. Turn off engine and disconnect the vacuum supply hose from the throttle body. Connect a long vacuum hose from the EGR vacuum port on the throttle body directly to the EGR valve vacuum port. Use a tee fitting to connect a vacuum gauge in the vacuum hose to the EGR valve, then start the engine and bring it up to 2,000 rpm. Watch the vacuum gauge, vacuum should be present and the EGR valve should open. On digital EGR valves, the resistance of the valve can be checked. By connecting an ohmmeter across the terminals on the valve, the windings can be checked for opens, shorts and high-resistance readings. If readings are not within specs, replacement of the EGR valve will be needed. Also, make sure that the EGR passages are not restricted or plugged. You will have to remove the valve to make this visual check. You can also use an exhaust gas analyzer to check an EGR system. Looking at the NOx readings at 2,000 rpm, the readings should be below 1,000 ppm. Troubleshooting an EGR valve Given the different types of EGR valves, it is always best to follow the troubleshooting procedures detailed in the service manual, however, there are a few generic steps that can help to pinpoint diagnosis: Read any fault codes on electronically controlled EGR valves using a diagnostic tool. Check that all vacuum lines and electrical connections are connected and positioned correctly. Use a vacuum gauge to check the vacuum supply hose for vacuum at 2000 to 2500 rpm. No vacuum at normal operating temperatures would suggest a loose hose, a blocked or faulty ported vacuum switch or solenoid or a faulty vacuum amplifier/pump. Check the vacuum solenoid while engine is running. On electronically controlled EGR valves, activate the solenoid with a scan tool and check the vacuum at end of pipe. If the solenoid does not open when energized, is stuck in the open or closed position or has a corroded electrical connection, loose wire or bad ground, EGR operation will be affected. Identify the root cause before replacing. If possible, check the movement of the valve stem at 1500 to 2000 rpm. The valve stem should move if the valve is functioning correctly -- if not, and there's vacuum, there's a fault. Apply vacuum directly to the EGR valve using either a hand vacuum pump or scan tool depending on the type of EGR valve. If there is no change in idle quality, then either the EGR valve is faulty or the passages are completely restricted. If the engine idles rough or stalls, the problem is being caused by a malfunctioning control system. Remove the EGR valve and check for carbon build up. Where possible, remove any carbon, being careful not to contaminate the diaphragm. Inspect the EGR passageway in the manifold for clogging and clean if required. Many engines have multiple EGR ports for discharging exhaust into the intake. If several ports plug up, all flow can be directed to a single cylinder. This can cause a misfire, which is very often misdiagnosed. Countless injection flushes and \"tune ups\" are needlessly sold for this problem, without success. Removing the intake and clearing the passages are the only repair. The carbon in the exhaust gas can also coat the throttle body plate. When this happens, rough idle and dying can occur. The engine may set a general misfire code, which is often misdiagnosed. Cleaning the throttle body will generally clear the problem. **Actual failure of the EGR valve is rare** Far more common are failures of the sensors that read and monitor the flow or the hoses and wires that control the system. **Diesel Particulate Filter** Diesel engines produce a variety of particles during the combustion of the fuel/air mix due to incomplete combustion. The composition of the particles varies widely dependent upon engine type, age, and the emissions specification that the engine was designed to meet. Two-stroke diesel engines produce more particulate per unit of power than do four-stroke diesel engines, as they burn the fuel-air mix less completely. Diesel particulate matter resulting from the incomplete combustion of diesel fuel produces soot (black carbon) particles. These particles include tiny nanoparticles---smaller than one micrometre (one micron). Soot and other particles from diesel engines worsen the particulate matter pollution in the air and are harmful to health. New particulate filters can capture from 30% to greater than 95% of the harmful soot. With an optimal diesel particulate filter (DPF), soot emissions may be decreased to 0.001 g/km or less.\] The quality of the fuel also influences the formation of these particles. For example, a high sulphur content diesel produces more particles. Lower sulphur fuel produces fewer particles, and allows use of particulate filters. The injection pressure of diesel also influences the formation of fine particles. Diesel particulate filters (DPFs) are an important component of the exhaust system in diesel-powered vehicles. They are designed to capture and store the soot and other harmful particulate matter produced during a diesel engine\'s combustion process. These particles can harm human health and the environment, so it\'s essential to have a mechanism to capture and remove them. DPFs are typically made from a ceramic material with tiny, precisely engineered pores that allow the exhaust gases to flow through while trapping the particulate matter. As the particulate matter accumulates on the filter, it can reduce the flow of exhaust gases and increase back pressure, leading to decreased engine performance and increased fuel consumption. To prevent these issues, DPFs undergo a process called regeneration, which involves burning off the trapped particulate matter to keep the filter clean and free-flowing. There are several types of regeneration methods, including active and passive regeneration. Here are a few key reasons why DPFs are vital: 1. **Reduce harmful emissions:** DPFs are designed to capture and remove the particulate matter generated during diesel combustion. These particles can be detrimental to human health and the environment, so it\'s essential to have a mechanism to capture and remove them. 2. **Improve air quality:** By reducing the amount of particulate matter released into the atmosphere, DPFs help to improve air quality and minimize the harmful effects of diesel emissions on human health. 3. **Comply with regulations:** Vehicles must meet strict emissions standards in many countries and regions, including the European Union and California. DPFs are critical to meeting these standards, and their use is legally mandated in these regions and throughout North America. 4. **Prevent engine damage:** A clogged DPF can cause increased back pressure, decreased engine performance, and increased fuel consumption. Regular maintenance of DPFs can help prevent engine damage and ensure that your vehicle continues to operate safely and efficiently. Overall, DPFs are essential to modern diesel technology, and their importance cannot be overstated. Understanding the role of DPFs in reducing harmful emissions and maintaining their proper function is critical for ensuring that your vehicle operates safely and efficiently while minimizing its impact on the environment. A DPF system will have a few parts consistent across nearly all heavy-duty trucks, while there are some automotive systems that utilize different technology. The main components utilized in a DPF system are 1. DPF filter (Diesel Particulate Filter) 2. Diesel oxidation catalyst (DOC) filter 3. Dosing injector 4. DPF pressure differential sensor 5. Multiple exhaust gas temperature sensors 6. EGR system 7. Turbocharger All these components are engineered by the manufacturer to work together in order for the DPF system to operate as intended. How do Diesel Particulate Filters work? Diesel particulate filters (DPFs) trap and remove the particulate matter generated during diesel combustion. As the exhaust gases flow through the filter, the particulate matter becomes trapped in the filter\'s porous walls. Over time, this accumulation of particles can cause the filter to become clogged, resulting in increased back pressure and decreased engine performance. To prevent this from happening, DPFs go through a process called regeneration. During this process, the trapped particulate matter is burned off, which keeps the filter clean and free-flowing. There are two main types of regeneration methods: active and passive. Active regeneration uses a heat source to burn off the trapped particulate matter. This can be accomplished by fuel being misted upstream of the DOC by a doser valve. Active regeneration is generally more efficient than passive regeneration because it allows for more precise control over the regeneration process. Passive regeneration, on the other hand, relies on the heat generated by the engine to burn off the trapped particulate matter. This means the engine must reach a specific temperature for the regeneration process. While passive regeneration is less complex than active regeneration, it can be less efficient and unsuitable for all operating conditions. In contrast to higher temperature active regeneration, passive regeneration -- sometimes referred to as 'passive regen' -- uses normal exhaust temperatures and nitrogen dioxide (NO~2~) as the catalyst to oxidise PM in the DPF. NO~2~ reacts with the carbon of the soot particles to produce Carbon monoxide CO and Nitric Oxide NO. Active Regeneration, on the other hand, use an external source of heat to burn off the trapped particulate matter. This can be accomplished by fuel being misted upstream of the DOC by a doser valve or by injecting more diesel into the cylinder on the exhaust stroke post combustion stroke. The unburnt fuel oxidises in the Diesel Oxidation Catalyst (DOC) up stream of the particulate filter. This process generates a large amount of heat. Active regeneration is generally more efficient than passive regeneration because it allows for more precise control over the regeneration process. Active DPFs are typically more expensive than passive DPFs but may be necessary for vehicles that operate under a wide range of driving conditions. In both types of regeneration, the burned-off particulate matter is converted into harmless gases, such as carbon dioxide and water vapour, which are then released into the atmosphere. The choice between passive and active DPFs depends on several factors, including the driving conditions, the vehicle\'s operating requirements, and the cost. OE manufacturers have designed your diesel vehicle with the appropriate DPF suitable for its use. Understanding how DPF's work and how to maintain them can help ensure that your vehicle continues to operate efficiently and safely while minimizing its impact on the environment. What Are the Symptoms of a Blocked Diesel Particulate Filter? Oftentimes, blocked diesel particulate filters are caused by short journeys at low speeds. Vehicles operating at low speeds on short journeys are unable to meet the requirements for the filter to clean itself. DPFs can also fail due to poor servicing. The lifespan of a diesel particulate filter varies based on the application. For example, the Cummins ISX15 engine's filter has an interval for cleaning up to 400,000 to 600,000 miles---although it will need to regenerate regularly prior to cleaning. There are two broad type of particulate matter, combustible matter and non-combustible matter. Regeneration cleans out the combustible matter (soot) by converting carbon to carbon dioxide and burning of other combustible materials. Ash and other non-combustible materials will collect over time and eventually block the DPF. The only way to remove the non-combustibles is to remove the DPF and either blow the unit out with compressed air or wash it with a water spray. NOTE: Not all DPF can be cleaned in this manner, check manufactures requirements. DPFs may fail sooner if they are not well maintained. Additionally, filter blockage can be caused by using the wrong type of oil, performance modifications, using low-quality fuel, or even running the car frequently on a low fuel level. So how can you tell if your filter is blocked? Typically, when the filter becomes clogged or an error occurs in the system, an orange warning light will appear on your dashboard. This light varies based on the manufacturer but commonly appears like the image below. When this lights up, you know your filter is most likely blocked, and regeneration may be required. Diesel Particulate Filters do not fail regularly. In many cases, there is another fault causing the DPF to fail. If a vehicle is having DPF issues the root cause must be found and corrected. Check the crankcase ventilation system and the EGR system etc. for faults The key to maintaining a DPF is to ensure it's able to regenerate itself when it fills with soot (triggering the warning light). Both active and passive regeneration happen automatically and without driver input. Active regeneration can occur automatically any time the vehicle is moving. The exhaust gas temperature could reach 1500 F (800 C). Active regeneration is unknown to the driver except for some additional dashboard lamps being lit. The biggest sign to look for to determine if it is taking place is the 'high-exhaust temp' light, which will turn on once the aftertreatment doser starts to inject, increasing the temperature in the aftertreatment device. When operating conditions do not allow for DPF cleaning by active or passive regeneration, the vehicle may require an operator-activated parked regeneration. For this to take place, the vehicle must be standing still. The driver or technician brings the engine to operating temperature and initiates the parked regeneration by activating the dash controls or scan tool. This may take anywhere from 20 minutes to an hour, depending on ambient conditions and the type of engine or DPF system. In many cases, the vehicle will require an oil change at the conclusion of this process. Before initiating a parked regeneration, it's critical for the driver or technician to ensure the exhaust outlets are directed away from structures, vegetation, trees, flammable materials and anything else that may be damaged or injured by exposure to high heat. Not all DPF systems have a parked regeneration feature. The DPF, or rather the carbon trapped in the DPF, also assists in the reduction of Nitrogen Dioxide (NO~2~) emissions. A by-product of combustion is Nitrogen Monoxide or nitic oxide (NO). Nitric oxide (NO) is not considered to be hazardous to health at typical ambient conditions. Unfortunately, as nitric oxide passes through the Diesel Oxidation Catalyst, it is oxidised to Nitrogen Dioxide, a much more hazardous substance. Nitrogen Dioxide reacts with carbon, in the form of soot in the DPF, to produce Nitric Oxide and carbon monoxide or carbon dioxide. There is currently a large amount of research occurring on the next generation of DPFs. The DPF filter substrate promotes the reaction of NO~2~ with carbon to produce NO and Carbon Monoxide. The carbon monoxide would further be oxidised down stream to carbon dioxide. Research has shown that there can be a reduction of the NO~2~ emissions by as much as 98% The oxidation of the solid carbon soot to a gas would also reduce the load on the DPF and regeneration cycles would happen less often, resulting in better fuel consumption and overall, less emissions. The next generation of DPF will most likely be electrically heated for active regeneration rather than the addition of extra diesel. This will also reduce fuel consumption and reduce emissions. **Catalytic Converter System** What is a Catalytic Converter? The catalytic converter is located in the exhaust system and is designed for exhaust gases to pass through before being released to the atmosphere. The catalytic converter turns the harmful pollutants in vehicle exhaust systems into harmless gases such as steam or water vapour. When the exhaust gas comes into contact with the precious metals (or catalyst) found in the catalytic converter, a chemical reaction takes place that weakens the bonds of the polluting chemicals and allows them to easily convert into more desirable by-products of combustion. The heart of the catalytic converter is a \"ceramic monolith\". This is a honeycombed structure that has many small channels through which the exhaust gases flow. The honeycomb structure means the gases touch a bigger area of catalyst at once, so they are converted more quickly and efficiently. The entire surface of the monolith is coated with a washcoat of aluminium oxide. This enlarged surface is then coated again with the precious metals platinum and rhodium or palladium and rhodium in a ratio of 5:1. This creates reaction surfaces for oxidation, i.e. reduction, of the exhaust pollutants. There may be several monoliths in the catalytic converter to compensate for expansion due to the high exhaust gas temperatures. The pressure-sensitive monoliths are provided with an elastic intermediate layer in a two-shell, thermally insulated stainless steel casing. A specific operating temperature is necessary for the catalytic converter to function correctly.  Signs of Catalytic Converter Issues So what happens when a catalytic converter goes bad? Considering the role the part plays in a vehicle's exhaust system, a range of symptoms can arise when it starts to experience wear and tear. Some examples to watch out for include: 1. Declining fuel efficiency: If a catalytic converter becomes clogged, it can reduce the amount of airflow through your engine. To compensate, your engine might start to burn more fuel than usual, resulting in a noticeable drop in fuel efficiency. 2. Check warning light: A check engine light can indicate a range of things. However, there is a diagnostic system on cars manufactured after 1996 that will test the catalytic converter. If your converter is malfunctioning, the air-to-fuel ratio sensors might trigger the warning light to come on. 3. Smelling rotten eggs: The catalytic converter might experience internal damage that causes it to have a hard time converting exhaust gases. The result can be a sulphuric "rotten egg" smell. 4. Issues starting the engine: The exhaust gases in your vehicle have to escape. A clogged catalytic converter can prevent this from happening as effectively. This can result in increased exhaust pressure and cause your car to sputter or stall when you're trying to get it going. 5. Poor acceleration: Again, the exhaust gases have to escape somehow. Trapped exhaust and increased pressure from a clogged converter might cause you to have trouble accelerating your car. You might notice jerking or stalling when you try to do so. 6. Failed emissions test: Many states require regular emissions testing on vehicles, and if you don't pass yours the culprit very well could be your catalytic converter. Failing this test might be coupled with the other symptoms mentioned above. There are two types of catalytic converters used with spark ignition vehicles, machinery etc., and diesel engines used in trucks, machinery, etc. They are an oxidation type catalyst and a reduction type catalyst. These classifications are determined by the type of chemical reaction that occurs with-in each catalyst. The Oxidation Catalyst In spark ignition vehicles, an oxidation catalyst is usually referred to as a two-way catalytic converter. The oxidation catalyst fitter to a diesel engine is referred to as a Diesel Oxidation Catalyst (DOC). They primarily operate the same way but there are some variations in their function. An oxidation reaction occurs when a compound or element reacts with oxygen to form a new compound. In an oxidation catalytic converter carbon monoxide (CO) and unburned fuel in the form of hydrocarbons (HC) react with the oxygen to form carbon dioxide (CO~2~) and water (H~2~O). In petrol engines, extra air has to be added to the exhaust gasses to provide extra oxygen for these chemical reactions to occur. This was done by the addition of and air pump or reed valves in the exhaust system. The air pump would pump extra air into the exhaust gas flow. The reed valve system would utilise the low pressure pulses of the exhaust gas flow to open and admit extra air into the exhaust gas flow The advent of precise air-fuel ratios in petrol engine has led to the use of three way catalytic converters in most modern petrol engines. Two way catalytic are no longer commonly used. Diesel Oxidation Catalysts (DOC) Diesel Oxidation Catalysts are catalytic converters designed specifically for diesel engines and equipment to reduce Carbon Monoxide (CO), Hydrocarbons (HC) and Particulate Matter (PM) emissions. DOC\'s are simple, inexpensive, maintenance-free and suitable for all types and applications of diesel engines. How Diesel Oxidation Catalyst Works **Figure 1. How Diesel Oxidation Catalyst (DOC) Works** Modern catalytic converters consist of a monolith honeycomb substrate coated with platinum group metal catalyst, packaged in a stainless steel container. The honeycomb structure with many small parallel channels presents a high catalytic contact area to exhaust gasses. As the hot gases contact the catalyst, several exhaust pollutants are converted into harmless substances: carbon dioxide and water. The diesel oxidation catalyst is designed to oxidize carbon monoxide (CO), gas phase hydrocarbons (HC), and the Soluble Organic Fraction (SOF) the of diesel particulate matter to CO~2~ and H~2~O: CO + O → CO~2~ HC + O → CO~2~ + H~2~O SOF + O → CO~2~ + H~2~O Diesel exhaust contains sufficient amounts of oxygen, necessary for the above reactions. The concentration of O~2~ in the exhaust gases from diesel engine varies between 3 and 17%, depending on the engine load. The catalyst activity increases with temperature. A minimum exhaust temperature of about 200°C is necessary for the catalyst to \"light off\". At elevated temperatures, conversions depend on the catalyst size and design and can be higher than 90%. Conversion of diesel particulate matter is an important function of the modern diesel oxidation catalyst**.** The catalyst exhibits a very high activity in the oxidation of the organic fraction (SOF) of diesel particulates. Conversion of SOF may reach and exceed 80%. At lower temperatures, say 300°C, the total DPM conversion is usually between 30 and 50% (Figure 3). At high temperatures, above 400°C, a counterproductive process may occur in the catalyst. It is the oxidation of sulphur dioxide to sulphur trioxide, which combines with water forming sulphuric acid: A formation of the sulphate (SO4) particulates occurs, outweighing the benefit of the SOF reduction. Figure 3 shows an example situation, where at 450°C the engine-out and the catalyst total DPM emissions are equal. In reality the generation of sulphates strongly depends on the sulphur content of the fuel as well as on the catalyst formulation. It is possible to decrease DPM emissions with a catalyst even at high temperatures, provided suitable catalyst formulation and good quality fuels of low sulphur contents are used. On the other hand, used with high sulphur fuel will increase the total DPM output at higher temperatures. This is why diesel catalysts become more widespread only after the commercial introduction of low sulphur diesel fuel. The most common forms of NOx gasses formed during diesel combustion are Nitrogen Monoxide(NO) and Nitrogen Dioxide (NO~2~). The diesel oxidation catalyst may also cause the oxidation of the relatively harmless Nitrogen Monoxide, also called Nitric Oxide, to the more harmful nitrogen dioxide. NO + O → NO~2~ The Diesel Oxidation Catalyst is located prior to the Diesel Particulate Filter, usually in the same housing. The oxidation process generates large quantities of heat which helps in the continuous regeneration process of the DPF. Most Diesel Oxidation Catalysts operate at around 250° to 300° C, getting up to 600° C while oxidising the extra diesel injected during a regeneration cycle. This extra heat enable the burn off of the combustible material captured by the diesel particulate filter. The Reduction Catalyst The reduction catalyst removes oxides of nitrogen (NO~X~) from the exhaust gasses. A reduction is where an oxide compound such as NO~2~ has the oxygen removes to reverse any oxidation reaction the may have occurred, returning the compound to an unoxidised state. Example Nitrogen dioxide converter to nitrogen and oxygen. 2 NO → N~2~ + O~2~ As the oxidation catalysts in either petrol or diesel engines can not remove NO~X~ emissions some further after treatment is required. In Petrol engines, the use of electronics allowed precise control of the air fuel ratio entering the combustion chamber. This was mainly achieved be the use of the oxygen (lambda) sensor in the exhaust to provide a feedback circuit to the engine management system, which controlled the amount of oxygen in the exhaust gas stream. A reduction catalyst could now be used with the oxidation catalyst to control NO~X~ emissions. This became known as a 3 way catalytic converter and is now the most common type of converter used on modern petrol powered motor vehicles. These units do not require additional oxygen to operate which alleviates the need for air pumps or reed valve assemblies. The way reduction catalyst causes the NO~X~ gasses to chemical react with the carbon monoxide to form Nitrogen gas, Oxygen gas and carbon dioxide gas. The oxygen derived from the reduction gas is now used in the oxidation catalyst section to convert and left over Carbon monoxide and Hydrocarbon gasses to carbon dioxide and water. A petrol engine must operate at a very precise air/fuel ration called the stoichiometric ratio for this reaction to happen. The exhaust oxygen sensor helps maintain this ratio and must always be in operational condition for the system to function correctly. Unfortunately as diesel engines do not have precise control of there air fuel ratio, a similar system for controlling NO~X~ emissions can not be used. Diesel engines use a system call Selective Catalytic Reduction System Selective Catalytic Reduction System Selective Catalytic Reduction (SCR) is an advanced active emissions control technology system that reduces tailpipe emissions of nitrogen oxides (NOx) down to near-zero levels in newer generation diesel-powered vehicles and equipment. The SCR system involves several components packaged together with other parts of the emissions control system. Each manufacturer has its own variations of the type and sequencing of different components in the system. SCR is an active emissions control system. Hot exhaust gases flow out of the engine and into the SCR system where aqueous urea known as Diesel Exhaust Fluid (DEF), most commonly called AdBlue, is sprayed onto a special catalyst. The DEF sets off a chemical reaction in the exhaust on a special catalyst that converts nitrogen oxides into nitrogen, water, and tiny amounts of carbon dioxide (CO2), natural components of the air we breathe. The exhaust also passes through a particulate filter somewhere in the system, usually prior to the SCR, and then is then expelled through the vehicle tailpipe. The design of SCR technology is such that it permits nitrogen oxide (NOx) reduction reactions to take place in an oxidizing atmosphere. It is called \"selective\" because it reduces levels of NOx using ammonia as a reductant within a catalyst system. The chemical reaction is known as \"reduction\" where the DEF is the reducing agent that reacts with NOx to convert the pollutants into nitrogen, water, and tiny amounts of CO2. The DEF is rapidly broken down to produce the oxidizing ammonia in the exhaust stream. The SCR unit has a reduction catalyst at the beginning that causes the NO~X~ emissions to react with the ammonia component (NH~3~) of the diesel exhaust fluid to combine and form nitrogen gas (N~2~) and water (H~2~O). A further oxidation catalyst is placed behind the reduction catalyst to convert any left over ammonia exiting the reduction catalyst to nitrogen gas (N2) and water (H2O). These are usually referred to as a Clean up catalyst (CUC) or an Ammonia slip Catalyst (ASC). SCR systems are active systems. Compared to the passive catalytic converters on gasoline vehicles, SCR systems require replenishing Diesel Exhaust Fluid (DEF) on a periodic basis to ensure emissions system performance. The need to refill DEF is directly related to vehicle fuel consumption. Failure to refill DEF tanks can result in immobilization of the vehicle or machine and a requirement for service. Typically DEF consumption is around 3% of fuel consumption. Regular maintenance of the SCR system is critical for several reasons. First, it ensures that the system effectively reduces NOx emissions, keeping the vehicle compliant with environmental regulations with effective aftertreatment procedures. Second, a well-maintained SCR system can improve fuel efficiency and reduce operational costs. Third, it prevents costly repairs and downtime caused by system failures. Routine maintenance includes checking DEF levels, inspecting for leaks, and ensuring the correct functioning of sensors and injectors. Troubleshooting Common SCR System Issues Despite regular maintenance, SCR systems can experience issues that require troubleshooting. Common problems include: 1. DEF Quality Issues: Using poor-quality DEF can lead to deposits in the system, reducing its efficiency. Always ensure the use of high-grade DEF for efficient SCR aftertreatment. 2. Injector Failures: The DEF injector can become clogged or malfunction, leading to incorrect DEF dosing. Regular inspections can identify issues early. 3. Sensor Malfunctions: NOx and temperature sensors are critical for system operation. Faulty sensors can provide incorrect readings, leading to system errors. 4. Catalyst Efficiency: Over time, the catalytic converter can become less efficient due to contamination or damage. Monitoring system performance can help identify when a catalyst replacement is necessary. 5. Poor DPF Performance: The DPF procedure occurs before the exhaust reaches the SCR system. With poor DPF performance, soot or particulate matter may seep through and cause damage to other exhaust components. The SCR will be susceptible to additional degradation when contaminates enter. Diagnostic Procedures for SCR Systems Diagnosing issues in SCR systems often requires specialized tools and knowledge. Diagnostic procedures start by reading fault codes. Modern trucks are equipped with onboard diagnostics that can provide fault codes indicating specific issues with the SCR system. Once the problem has been identified, a physical inspection of the SCR components, including the DEF tank, lines, injector, and sensors, can identify visible issues like leaks or damage. Once identified and repaired, 205 Diesel Repair will measure our repair\'s effectiveness with a performance test. Testing becomes essential to identify inefficiencies or malfunctions. Your heavy-duty truck will be under various operating conditions to further diagnose SCR system issues. Signs of SCR System Damage Operators and fleet managers should be aware of signs indicating potential SCR system damage. These include: 1. Increased DEF Consumption: An unusual increase in DEF usage can indicate a problem with the system's efficiency. 2. Unusual Exhaust Smoke: ineffectively NOx emissions reduction can lead to excessive exhaust smoke. This smoke might appear denser or differently coloured than normal, indicating incomplete aftertreatment processes. 3. Reduced Engine Performance: If the SCR system is not functioning correctly, it can lead to reduced engine performance or even enter a derated mode to limit potential damage. 4. Warning Lights: Dashboard warning lights specific to the SCR system can indicate issues. 5. Ammonia Odor: A properly functioning SCR system should effectively convert DEF into harmless nitrogen and water vapor. A malfunctioning system, however, may emit a noticeable ammonia smell from the exhaust, indicating an issue with the DEF dosing or catalytic conversion process. 6. Excessive System Regeneration Cycles: The SCR system may undergo more frequent regeneration cycles if it is struggling to maintain efficiency. An increase in these active regeneration processes can suggest issues such as clogged injectors or inefficient catalytic conversion, requiring attention. 7. Abnormal DEF Crystallization: While some DEF crystallization is normal, excessive or abnormal crystallization around the injector or other SCR components can be a sign of DEF over-injection, leaks, or temperature control issues within the system. This crystallization, if not addressed, can lead to blockages and further damage to the SCR system. SCR System Repairs When repairs are necessary, they should be carried out by qualified technicians. Repairs might involve: 1. Replacing DEF Injectors 2. Sensor Replacements 3. Catalytic Converter Servicing 4. Component Repairs **Exhaust Gas Analysis** Experts believe that analysis of the exhaust help diagnose problems and improve efficiency. 1. Oxygen: Most engines would need oxygen for the burning of fuel. Professionals use the analysers at the tailpipe, indicating unburned oxygen and representing a lean air/fuel mixture. 2. Hydrocarbons: The analyser measures the amount of unburned fuel and measures in the format of ppm (parts per million). 3. Carbon dioxide: Levels of CO2 represents the amount of burned fuel. 4. Carbon monoxide: High CO indicates a rich fuel mixture and means partially burned fuel. 5. Particulate Matter: Measures the performance level of the DPF. Specialist testing machines are required to test the exhaust gasses of a vehicle. It is important to regularly perform an analysis of the exhaust gasses to check the operation of the engine and exhaust after treatment system to ensure effective and efficient operation of the machine's operation. Exhaust Gas Analysis is usually an inspection item performed by licencing, police and other transport authorities when determining the roadworthiness of an on road vehicle. Many companies and mine sites require exhaust analysis to comply with their organisational requirements. Penalties for excessive emissions can include large fines which may include a daily penalty until rectified. **Exhaust Smoke Analysis** Diesel engine smoke comes in three colours: white, black and blue. Consistent smoke coming from the exhaust most likely indicates a deeper internal problem with the engine. A small puff of smoke during quick acceleration is acceptable with older diesel engines due to a lag before the turbocharger's air flow can match the increased volume of diesel fuel injected into the cylinders. Newer electronic diesel engines with [common rail injectors](https://en.wikipedia.org/wiki/Common_rail) simultaneously match the speed of the turbo with the metered flow of diesel fuel into the cylinder. White Smoke: White smoke coming from the exhaust usually points to one point of failure: the injectors. Usually, white smoke indicates that the diesel fuel is not burning correctly. Unburned diesel fuel will make its way through the exhaust completely unused. Be careful of white smoke as it will irritate your eyes and skin. If white smoke occurs during a startup in freezing temperatures, then goes away, it usually indicates frozen deposits of soot which expanded around the rings then burned away once the engine warmed up. The [use of glow plugs during cold starts](https://www.capitalremanexchange.com/12-tips-for-starting-diesel-engines-in-the-cold/) and/or the use of a flushing solvent to remove engine sludge is recommended. Common Causes of White Smoke: Damaged Injectors\ Faulty Injection Timing\ Damaged Crankshaft Keyway\ Damaged Timing Gear\ Low Cylinder Compression\ Damaged Rings or Cylinder Liners\ Water mixed in the Diesel Fuel (Cracked Head Gaskets, Cylinder Head or Block)\ Damaged Fuel Lines\ Low Fuel Pressure to the Fuel Pump\ Damaged or Incorrect Fuel Pump Timing Black Smoke: Black smoke, unlike white smoke, contains a high concentration of carbon exhaust particles. The combustion of diesel fuel in the cylinders breaks down the long chain of carbon molecules to smaller and smaller molecular chains. When the exhaust leaves the engines the byproduct is a combination of carbon dioxide and water. If something goes wrong during combustion the chemical reaction taking place is not as robust, causing long tail hydrocarbons to be left completely intact and then expelled in the form of smog or soot. Partial burning of diesel fuel results in large carbon dioxide particles as well as greenhouse gasses which contribute to air pollution. The advent of the Selective Catalytic Converter, Diesel Exhaust Fluid and Diesel Particulate Filter all helped to regenerate exhaust back into the combustion chamber to further break down particulate matter. Black smoke is the most common smoke colour coming from a diesel engine and most likely indicates something is wrong during the combustion of the diesel fuel. When diagnosing the problem the first place to look at is the mixture of air and fuel flow into the cylinders. The engine could be delivering too much fuel, not enough fuel, too much air or simply not enough air. Common Causes of Black Smoke: Clogged Air Cleaner\ Damaged Injectors\ Bent Injector Nozzles\ Incorrect Injector Timing\ Clogged Air, Fuel or Oil Filters\ Damaged Injection Pump\ Damaged/Clogged EGR Cooler\ Damaged Turbocharger\ Damaged Intercooler\ Over-Fueling the Engine\ Wrong Blend of Diesel Fuel For Temperature\ Cracked or Clogged Valves in Cylinder Head\ Improper Valve Clearance\ Low Compression due to Damaged Piston Rings\ Excessive Engine Sludge Build Up Blue Smoke: Blue engine smoke is the rarest type of smoke emanating from a diesel engine. The presence of blue smoke is an indication of burning oil. Blue smoke should not be ignored but is common when [[starting an engine in a cold weather]](http://www.thedieselstop.com/forums/f23/blue-smoke-cold-start-most-likely-cause-s-303439/). The oil thins out when it is cold and some could escape into the cylinder and be burnt. Cold temperatures can cause older more worn rings to unseat just a bit due to deposits found around the rings or cylinders. Cylinder glaze, or the smooth deposits left behind from the piston going up and down, can also build up over time and burn. The seal between the combustion chamber and crankcase should be completely sealed after the initial break-in period. The [use of suitable assembly grease or Molybdenum Disulfide](https://www.capitalremanexchange.com/what-is-the-best-type-of-assembly-grease/) during the engine rebuild will help the rings to seat properly during initial startup as well as burn off any carbon deposits. Common Causes of Blue Smoke: Damaged or Worn Piston Rings\ Damaged or Worn Cylinders\ Damaged or Worn Guides\ Damaged or Worn Stem Seals\ Overfill of Engine with Oil\ Damaged Lift Pump\ Fuel Mixed with Oil\ Cylinder Glaze Burning\ Wrong Grade of Oil No matter the colour of the smoke it is not something you should ignore. A properly working and maintained diesel engine should produce no visible smoke. Make sure to shut down the engine immediately if you encounter excessive smoke as further heat or load could severely damage the engine further. **Basic Maintenance of Emission System** 5 Things To Know About Diesel Emissions Systems Maintenance and Repair The maintenance of your diesel emission system is a big deal. However, it can significantly impact machine performance, fuel efficiency, and fuel economy. Here are some things you should know about maintaining and repairing diesel emission systems: 1\. Diesel emissions system maintenance is critical to ensure machine health and the environment's health. Emissions systems are complicated, but they're necessary to reduce nitrogen oxide. A diesel emissions system keeps a vehicle running smoothly and efficiently. When it's working correctly, you don't have to worry about emissions failures and visible smoke from the engine harming the environment. However, if you're not treating your emissions system with care, you could damage your engine performance and hurt the environment. Systems maintenance checks from diesel service technicians can be done during your regular service interval. Still, they're often recommended at 15,000-mile intervals or every 30 months, whichever comes first (check with your diesel engine manufacturer for details). 2\. Emissions systems should be appropriately inspected before servicing. First and foremost, emissions systems should be appropriately inspected before servicing. If the diesel engine control system is not in good working order, replacement is usually your best bet. Always check your machine's emissions system before servicing it. This way, you can ensure that your problem is related to this system and not something else. In addition, any issues with the system or components will be detected during these inspections and can be addressed before they become more severe service problems. 3\. Fuel filters should always be replaced during regular maintenance. For a diesel machine to work correctly, it needs regular maintenance, such as filter replacements, to ensure that its parts stay clean and in good working order. By replacing fuel filters, you can expect machines to function effectively. When diesel technicians inspect an emissions system, they check for cracks or holes in the DPF that might let soot escape into the atmosphere instead of being trapped inside it. They also make sure no leaks are coming from any other part of the system and inspect the exhaust pipe, hoses, and connections for signs of wear or damage that might lead to future problems in engine performance. 4\. Diesel emissions systems can have manufacturing defects. Diesel engine models are manufactured to the highest possible quality standards and undergo rigorous emissions tests before their release onto the market. However, these systems are not immune to defects. A defective part can slip through during production and cause problems, making your diesel engine emit more pollution than it should. In addition, these defects can cause your vehicle to fail your state's emissions standard smog check, even if you've done nothing wrong. Thankfully, diagnostic scan tools and kits provide everything you need to diagnose and repair your heavy-duty diesel trucks, buses, and trailers. So, if your engine performance isn't up to par, this kit can help diagnose and solve emission problems. 5\. Emissions systems contain sensitive components that may require replacement even if you often don't drive your vehicle. You may have a diesel vehicle but not drive it often. That's fine---many people with diesel vehicles don't use them as much as they would like. But there's something you should know: Diesel emissions systems contain sensitive components that may require replacement even if you don't drive your vehicle often. Even when there isn't any normal engine wear and tear, the fuel filter can get clogged with dirt and other particles. The more these particles build-up, the harder it will be for your truck or machine to run smoothly and efficiently. DIY Maintenance Tips For The Vehicle Owner If you're a vehicle owner with a diesel engine, it's essential to keep up with regular maintenance so that your car avoids emissions-related failure. Serviceability of the system can be made by performing the following checks: Checking your engine oil regularly: It's essential to watch how much oil your diesel machine uses. If your engine operation uses more than one quart of oil per 1,000 miles of driving, it may be time for new parts or automotive repair. Checking the fuel tank regularly: If there are any problems with your tank, they will be noticed by checking them out regularly. You should also check your gas cap regularly since this will help reduce emissions from vehicles from leaking into the atmosphere when they are not supposed to be there! Changing your air filter as needed: If there are particles in your air filter that cannot be removed---like dust or dirt---you should replace it immediately. Changing the filter ensures you don't damage other parts of your engine, like valves or pistons!