Exhaust Gas Recirculation (Egr) System - Navistar International DT 466 Diagnostic/Troubleshooting Manual

Exhaust Gas Recirculation (EGR) System

The EGR system includes the following:
• EGR control valve
• EGR cooler
• Air intake manifold
• Inlet and EGR mixer duct
• Exhaust manifold
• Exhaust gas crossover
The Exhaust Gas Recirculation (EGR) system
reduces Nitrogen Oxide (NOx) emissions.
NO forms during a reaction between nitrogen and
X
oxygen at high temperature during combustion.
Combustion starts when fuel is injected into the
cylinder before or slightly after the piston reaches
top-dead-center.
EGR Flow
Some exhaust from the exhaust manifold flows into
the EGR cooler. Exhaust from the EGR cooler flows
through the exhaust gas crossover to the EGR valve.
When EGR is commanded, the EGR control valve
opens allowing cooled exhaust gases to enter the
EGR mixer duct to be mixed with filtered intake air.
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
1 ENGINE SYSTEMS
EGR Control Valve
Figure 15 EGR control valve
1.
2.
3.
The EGR valve uses a DC motor to control the position
of the valve assembly. The motor pushes directly
on the valve assembly. The valve assembly has two
valve heads on a common shaft.
The
components, a valve, an actuator motor, and
Integrated Circuit (IC). The IC has three Hall effect
position sensors to monitor valve movement. The
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
Connector
DC motor with position sensor
Valve assembly
EGR actuator consists
23
of three major