
RENR9968-02 15
Systems Operation Section
Turbocharger
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Illustrati
on 11
Turbocharger
(12) Air inlet
(13) C ompressor housing
(14) Compressor wheel
(15) Bearing
(16) Oil inlet port
(17) Bearing
(18) Turbine housing
(19) Turbine wheel
(20) Exhaust outlet
(21) Oil outlet port
(22) Exhaust inlet
The turbochar
ger is mounted to the exhaust manifold
of the engine. A ll of the exhaust gases go from the
exhaust manifold through the turbocharger.
The exhaust gases enter the turbocharger and the
turbine wheel is turned. Because the turbocharger
turbine whee
l is connected by a shaft to the
turbocharger compressor wheel, the turbine wheel
and the compressor wheel turn at very high speeds.
The rotatio
n of the compressor wheel pulls clean
air through the compressor housing air inlet. The
action of the compressor wheel blades causes a
compressio
n of the inlet air. This compression allows
a larger amount of air to enter the engine. With more
air in the engine, the engine is able to burn more fuel.
The overal
l effect is an increase in power.
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Illustration 12
Turbocharger with wastegate
(23) Canister
(24) Actuating lever
The engine can operate under conditions of low
boost (lug). Low boost is a condition that occurs
when the turbocharger produces less than optimum
boost pressure. There is a spring that is inside
canister (23). Under low boost, the spring pushes on
the diaphragm in canister (23). This moves actuating
lever (24). The actuating lever closes the wastegate,
which will allow the turbocharger to operate at
maximum performance.
Under conditions of high boost, the wastegate opens.
The open wastegate allows exhaust gases to bypass
the turbine side of the turbocharger. When the
boost pressure increases against the diaphragm in
canister (23), the wastegate is opened. The rpm of
the turbocharger is limited by bypassing a portion of
the exhaust gases around the turbine wheel of the
turbocharger.
Note: The calibration of the wastegate is preset
at the factory. No adjustment can be made to the
wastegate.
Bearing (15) and bearing (17) in the turbocharger use
engine oil that is under p ressure for lubrication. The
lubrication for the bearings flows through oil inlet port
(8) and into the inlet port in the center section of the
turbocharger cartridge. The oil exits the turbocharger
through oil outlet port (21). The oil then returns to
the engine oil pan through the oil drain line for the
turbocharger.
The turbocharger center housing of the turbocharger
is cooled by engine coolant. The c oolant flows from
the thermostat housing to the turbocharger center
housing. The coolant flow keeps the components of
the turbocharger’s center housing cool in order to
prevent oil coking in the bearing area.