MBE 4000 SERVICE MANUAL EXHAUST GAS RECIRCULATION (EGR) SYSTEM The purpose of the Exhaust Gas Recirulation (EGR) system is to reduce engine exhaust gas emissions in accordance with EPA regulations. The EGR system consists of: EGR Cooler EGR Control Valves Reed Valves EGR Charge Air Mixer The MBE 4000 engines for on-highway EPA 2004 regulation applications use a cooled EGR system. Part of the exhaust gasses from the front three cylinders are routed from the exhaust manifold through the EGR cooler, past control and reed valves, and are mixed with the intake manifold charge air.
The addition of cooled exhaust gasses back into the combustion airflow reduces the peak in cylinder combustion temperature. Less oxides of nitrogen (NOx) are produced at lower combustion temperatures. The recycled exhaust gasses are cooled before engine consumption in a tube and shell engine water cooler. See Figure 11. 1. Engine 5. EGR Cooler 2. Intake Air 6. EGR Shutoff Valve 3. EGR Modulated Valve 7. Exhaust Air 4. Reed Valves Figure 11 Air flow Diagram through Engine with EGR System All information subject to change without notice. 16 6SE412 0403 Copyright © 2004 DETROIT DIESEL CORPORATION