Detroit Diesel MBE 900 Technician Manual page 39

PRELIMINARY MBE EGR TECHNICIAN'S GUIDE
The second valve, not on the MBE 906, is a reed valve assembly downstream from the EGR
cooler. See Figure 2-17. The reed valves ensure that while the EGR control valve is open, there
is no reverse airflow from the intake system into the exhaust manifold. When the exhaust
manifold pressure is higher than the intake manifold pressure, flow occurs. When the pressures
are reversed, the reed valves prevent flow. Back flow could otherwise occur since the average
intake manifold pressure is higher than the average exhaust manifold pressure. See Figure 2-18.
Figure 2-17 Reed Valves
2-23
All information subject to change without notice. (Rev. 5/05)
7SE940 0505 Copyright © 2005 DETROIT DIESEL CORPORATION