Component Description For The Turbocharger - GF09.40-D-4010HDA
ENGINE 651.955/957 in MODEL 906
Location
The low-pressure turbocharger and the high-pressure turbocharger create a unit and are located on the right on the crankcase below the exhaust manifold.
Task
Both turbochargers generate the boost pressure dependent on the load condition of the engine.
The charging increases the air mass used in the engine and increases the engine output.
Function
The necessary boost pressure is generated by the high pressure and the low-pressure turbocharger or just by the low-pressure turbocharger according to the load condition of the engine.
For charging by the high pressure and the low-pressure turbocharger a larger or a smaller portion of the exhaust flow in the exhaust turbine housing of the high-pressure turbocharger upstream of the high-pressure turbocharger turbine is directed directly to the low-pressure turbocharger turbine wheel dependent on the boost pressure needed. In this way the low-pressure turbocharger turbine wheel is driven by more or less exhaust energy. Distribution of the exhaust flow is regulated by the position of the boost pressure control flap.
The wastegate is closed in this case.
If the low-pressure turbocharger is in the position to build up the whole boost pressure on its own, the boost pressure build up takes place by the low-pressure turbocharger. The boost pressure is limited over the wastegate.
The CDI control unit (N3/28) monitors the boost pressure that is actually produced via the boost pressure sensor (B5/6). The low-pressure turbocharger boost pressure sensor (B5/9) detects the boost pressure downstream of the low-pressure turbocharger. By comparing the boost pressure actually generated with the boost pressure stored in the characteristic map and the boost pressure downstream of the low-pressure turbocharger, it is possible to detect faults at the high-pressure and low-pressure turbocharger.
The vacuum cells and the adjusting rods for the respective flap and the wastegate can be disassembled if necessary. After successful assembly it is necessary to establish the basic setting of the vacuum cells and the adjusting rods.
When assembling the vacuum lines one should take note of the color markings on the vacuum line and the vacuum unit. There is a danger of engine damage if the assembly work is done wrongly.