What is an EGR System?

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Climate change has been a global cause of concern for the past two decades. As a result, greenhouse gas emissions have been placed under a microscope, as the leading cause of global warming. This has led to the creation of increasingly severe gas emission restrictions in the trucking industry, and hefty penalties for non-adhering individuals and companies. These restrictions encouraged design and engineering improvements in trucking mechanics and led to the incorporation of the Exhaust Gas Recirculation system in most recent diesel car models.

Air is mostly composed of Oxygen and Nitrogen. During the combustion processes in engine cylinders, the fuel combines with air and temperatures spike, causing the release of NOx gases. The Exhaust Gas Recirculation (E.G.R) system refers to a variety of engine components working together to minimize the amount of Nitrogen Oxide(s) being released from engine cylinders during combustion processes.

EGR systems have been around since the early 1970s, but they've had to survive multiple structural and design changes to become the diesel engine components we now know. While it operates mostly as a pollutant-inhibitor, your EGR valve constantly interacts with other versatile parts of your engine, such as the exhaust and intake manifolds and the engine computer. Therefore, clogging and other damage can lead to slowed speeds and more serious engine failures.

How EGR Systems Work

EGR systems prevent the waste of fuel from engine exhaust fumes, which would usually be observable in the black or blue smoke released by old diesel vehicles. EGR systems work by re-using a portion of the exhaust gas produced by the combustion processes in engine cylinders. This gas is pulled back into the combustion chamber, combining it with fresh air. This decreases the oxygen content in the chamber and introduces more water vapor into the newly formed gas. The peak combustion temperature then decreases, which limits the additional production of Nitrogen Oxides. It also maximizes the use of fuel, by re-introducing unused fuel into combustion chambers, to allow exhaust fumes to burn twice as the engine operates.

EGR systems feature coolers, which serve to lower the temperature of exhaust gases before they interact with the air in combustion cylinders. They also prevent the engine damage caused by combustion temperatures above 1600 Celsius or 2912 degrees F. By diverting exhaust gases back into combustion chambers; the EGR system is protecting your valves, pistons, and turbocharger from overheating.

Common EGR System Problems And How To Avoid Them

If you’ve recently noticed an increase in your NOx emissions, a malfunctioning EGR valve may be to blame. Its mechanism may be broken, and the valve is remaining open even when the engine is idling. If, on the contrary, the EGR valve mechanisms remain shut even when the engine is operating at high RPM, you may encounter occasional fuel detonation noises.

Most EGR system problems are caused by poor maintenance. Typically, the reputation of diesel as a low-cost fuel leads trucker to assume they can complete lengthy mileages before having to invest in maintenance servicing. Diesel owners also tend to wait until their EGR valve has completely broken down before replacing it, as it is a costly component. While failing EGR valves can often be “repaired” with professional cleaning, some problems can be symptoms of a deeper issue.

EGR systems can malfunction as the result of clogged EGR passages. As carbon builds up in the valve, diesel vehicle owners can see engine trouble codes, such as P0401 (Exhaust Gas Recirculation Flow Insufficient) pop up. Other codes, such as P0402, suggest that there is an excessive recirculation flow, which may be the sign of a failing valve circuit. Electrical wiring problems often lead to issues, and generally require a professional diagnosis.

Most EGR problems are caused by soot build-up, therefore can be solved with simple maintenance such as installing a cleaning tool on top of the valve, or ensuring you use the accelerating function more often. Allowing trucks to remain barely active for long periods is likely to encourage the clogging. Therefore, you may want to take your truck for a ride down a highway now and again, preferably allowing the engine to reach optimal performance temperature. Remember that the worst-case scenario of a malfunctioning EGR valve can cause a minor implosion, which can, in turn, damage the entire engine. Therefore, if a cleanup and high-speed 5-mile drive down the freeway results in no improvements, you may want to request a full replacement.

A Concluding Word

Fuel System services are essential to maintaining the health of your EGR system. A properly maintained and frequently used engine is unlikely to have any EGR problems unless its components have surpassed their life expectancy (which will depend on the vehicle model, its manufacturer, and your purchase date). By keeping your engine oil clean, you fence off most EGR system issues and save on significant repair costs in the long run.

If you’re looking to keep your truck in tip-top shape for the years to come, you may want to schedule a service. For more information about truck repair, call us at 877-520-4820 to speak to a member of our team!