Any loose objects or impurities can increase the back pressure for the exhaust gases from the
turbine wheel.
3.12.3 Checking the turbocharger
If a fault is suspected in the turbocharger, it can be located in the following way:
Procedure
1.
Visually inspect the turbine and compressor wheels. The vanes must not show any signs of damage,
deformation or wear caused by foreign objects.
2.
Investigate any oil leaks through the sealing
rings on the shaft in the turbine and
compressor housing.
NOTE: At low idling speed there is always a
certain amount of oil leakage on the
compressor side. However, this should not
cause too much concern unless the oil
consumption is too great.
Fig. 97
3.
Check the turbine shaft running clearance.
Place the stylus of a dial gauge against the
shaft and move the shaft sideways. Refer to
the clearance given in the specifications. See
Technical data, Turbocharger.
4.
Check the shaft end float. Place the stylus of
the dial gauge against the end of the shaft
and move the shaft axially. Refer to the
clearance given in the specifications. See
Technical data, Turbocharger.
Fig. 98
Result of the procedure
If any defects or wear are detected, the turbocharger should be replaced.
If the engine does not work correctly and the turbocharger is not defective or too worn, the fault could be
traced to one of the following items:
• Blocked air filter.
• Leakage in the inlet or exhaust systems. Leaking flange seal.
• Defective high-pressure pump or engine control unit.
• Defective or wrongly adjusted injectors.
• Low fuel pressure (e.g. blocked fuel filter).
• Low compression, wrong valve clearance.
3.12.4 Fitting the turbocharger
Locate the cause of the defects on the turbocharger. Remedy the fault before fitting the new turbocharger.
3. Maintenance
3-58 4th Generation Engines
8370 79492
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