The EGR valve position is controlled by DDEC. The ECU continuously monitors all engine operation modes and performs self diagnostic checks of RPM, load, altitude, air temperature, etc. and uses this information to determine the valve position.
When the EGR valve is closed, exhaust gas will flow from the exhaust manifold and through the turbine wheel in the turbocharger, and out the exhaust system. When the EGR valve is open, some of the exhaust gas is directed into the EGR cooler, through the delivery pipe, and into the intake manifold.
The insulator cannot be reused and should be replaced whenever the hydraulic actuator is removed from the EGR valve assembly. Reuse of the insulator shield will damage the EGR assembly.
To avoid injury from flying debris when using compressed air, wear adequate eye protection (face shield or safety goggles) and do not exceed 276 kPa (40 psi) air pressure.
If the EGR valve is excessively worn or defective, replace the valve assembly.
If the EGR valve is not excessively worn or defective, reuse the valve assembly.
Section 8.2.3 Assembly of Hydraulic EGR Valve Assembly
Assembly steps are as follows:
NOTICE:
The insulator shield must be replaced whenever the actuator assembly has been removed from the EGR valve assembly. Reuse of the insulator shield will damage the EGR assembly.
NOTICE:
The spline drive for the actuator assembly is keyed to ensure proper alignment with the shaft on the valve assembly. When performing step 1
, do not force any components onto the splined shaft. If excessive force is used, the splined shaft will be damaged.
Figure 5. EGR Hydraulic Actuator and Related Parts
NOTICE:
When performing step 2
, apply torque evenly to the bolts to ensure that the EGR valve assembly and hydraulic actuator assembly are not misaligned. Misalignment will cause the assemblies to bind.
Install two bolts (6) through the hydraulic actuator assembly (5) to secure to the EGR valve assembly (1). Torque bolts (6) to 24-28 N·m (18-21 lb·ft).
