TURBOCHARGER SYSTEM
DESCRIPTION
CAUTION: The turbocharger is a performance part
and must not be tampered with. The wastegate
bracket is an integral part of the turbocharger. Tam-
pering with the wastegate components can reduce
durability by increasing cylinder pressure and ther-
mal loading due to incorrect inlet and exhaust man-
ifold pressure. Poor fuel economy and failure to
meet regulatory emissions laws may result. Increas-
ing the turbocharger boost WILL NOT increase
engine power.
The turbocharger used on this vehicle is of the
variable turbine type (Fig. 1). These turbochargers
use the entire exhaust energy to boost efficiency of
the turbocharger and the engine.
The advantages of a turbocharger with variable
turbine geometry are:
• Higher charge pressure already in the lower and
in upper engine speed ranges.
• Higher torque as a result of improved cylinder
charge.
• Reduction in exhaust emissions as a result of an
improvement in the air supply of the engine.
• Increased power output as a result of the higher
charge pressure combined with a reduced exhaust
backpressure and thus improved charge cycle.
OPERATION
The exhaust gases of the engine are directed
through the exhaust manifold into the turbine hous-
ing onto the turbine wheel (Fig. 2). The flow energy
of the exhaust gases cause the turbine wheel to
rotate. Consequently, the compressor wheel, which is
connected through the turbine shaft with the turbine
wheel, is driven at the same speed. The fresh air
inducted by the compressor wheel is compressed and
passed to the engine (Fig. 2).
The charge pressure is controlled by varying the
position of the guide vanes (Fig. 2). The guide stud of
the control linkage of the boost pressure actuator
turns the adjusting ring in the turbine housing (Fig.
2). As a result, all the guide vanes whose guide studs
likewise mesh into the adjusting ring, are also
turned (Fig. 2).
At low speeds, the flow cross-section is reduced by
closing the guide vanes (Fig. 2). Consequently the
speed at which the exhaust gas impacts on the tur-
bine wheel is increased, as a result of which the
speed of the turbocharger and thus the charge pres-
sure rises.
At high engine speeds the guide vanes are increas-
ingly opened and the flow cross-section is thus
enlarged, as a result of which the speed of the turbo-
charger reduces and the charge pressure drops.
REMOVAL - TURBOCHARGER
WARNING: THE NORMAL OPERATING TEMPERA-
TURE OF THE EXHAUST SYSTEM IS VERY HIGH.
NEVER WORK AROUND OR ATTEMPT TO SERVICE
ANY PART OF THE EXHAUST SYSTEM UNTIL IT IS
COOL. CARE SHOULD BE TAKEN WHEN WORKING
NEAR THE TURBOCHARGER. THE TEMPERATURE
OF THE TURBOCHARGER RISES TO A HIGH LEVEL
AFTER A SHORT PERIOD OF ENGINE OPERATION
TIME.
NOTE: THERE IS NO PROCEDURE FOR REPAIRING
THE TURBOCHARGER. IF DAMAGE IS FOUND
DURING INSPECTION, THE TURBOCHARGER MUST
BE REPLACED.
(1) Disconnect negative battery cable.
(2) Disconnect oil separator hose from turbo-
charger air inlet hose.
Fig. 1 TURBOCHARGER LOCATION
1 - TURBOCHARGER
2 - CYLINDER HEAD COVER
3 - OIL SEPARATOR
4 - AIR INLET TUBE
5 - WASTEGATE ACTUATOR
11a - 2 EXHAUST SYSTEM AND TURBOCHARGER - 2.7L DIESEL WG
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