Hummer H1 Service Manual page 52

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TURBOCHARGER SERVICE AND DIAGNOSIS
Description
The turbocharger used on 6.5L diesel engines is a Borg-
Warner model 1H1 (Figure 2-7). Lubrication is by engine oil
from the engine lubrication system.
Boost is monitored by the PCM and controlled by the waste-
gate and electronic accelerator pedal. The pedal assembly con-
sists of a bracket, pedal and arm, and the pedal position sensor
(potentiometer); a conventional throttle linkage is not used.
The turbocharger is mounted in the lifter valley at the rear of
the engine block. It is positioned between the two halves of the
intake manifold.
A turbocharger is fundamentally an air pump used to generate
additional engine power. This is accomplished by increasing
volume and pressure of air entering the engine combustion
chambers. An increase in air volume allows a proportional in-
crease in fuel injected into the cylinders. The net result is a
denser fuel/air mixture. A denser mixture produces more power
when compressed and burned in the combustion chamber.
A turbocharger feature concerns the method of operation. The
turbocharger turbine and compressor impellers are rotated by
the flow of engine exhaust gases. As a result, separate drive
belts and pulleys are not needed.
TURBINE HOUSING
AND IMPELLER
EXHAUST
OUTLET
ROD
LEVER
WASTEGATE
VALVE
05745159
TURBINE/COMPRESSOR
SHAFT
Figure 2-8: Turbocharger Components (Typical)
TURBOCHARGER
Figure 2-7: Turbocharger and Vacuum Actuator
Mounting
The turbocharger used on 6.5L engines consists of a turbine
impeller and housing, a compressor impeller and housing, a
wastegate, a wastegate actuator and an impeller connecting-
shaft (Figure 2-8). A separate, belt driven vacuum pump sup-
plies vacuum for wastegate actuator operation.
AIR OUTLET
(TO MANIFOLD)
WASTEGATE VACUUM ACTUATOR
Engine 2-15
WASTEGATE
VACUUM
ACTUATOR
MANIFOLD
CROSSOVER
HOUSING
COMPRESSOR HOUSING
AND IMPELLER
FRESH AIR INLET
(FROM AIR CLEANER)