Man D 2866 LE 401, Repair Manual

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Turbocharger, trouble shooting
70
Before removing the turbocharger carry out the following checks
Turbochargers are frequently exchanged if the oil consumption is too high, the output too low or the intake
and/or exhaust gas noises appear to be abnormal. Subsequent inspections by the manufacturer of the sup-
posedly defective parts frequently prove the turbochargers to be in order.
To ensure that only defective turbochargers will be exchanged in future, the following checks are to be car-
ried out beforehand:
If the oil consumption is too high
– Check air filter for contamination,
– ensure that the engine room ventilation is adequate,
– check intake pipe for cross section reduction (owing e.g. to damage, contamination).
These causes lead to higher oil consumption owing to the increased vacuum on the intake side of the com-
pressor.
– Check outside of turbocharger for oil traces.
Oil consumption caused directly by turbocharger depends on the bearing wear and results in relatively early
mechanical damage.
If engine performance is not satisfactory
Correct adjustment of the
– delivery start,
– valve clearance,
– speed adjustment (to full load stop).
In addition, the following are to be checked:
– the compression,
– the air filters for contamination,
– the charge-air pressure,
– the pressure in the inlet chamber of the injection pump,
– the exhaust back pressure.
If you do not detect any possible cause in the above checks, check the turbocharger for:
– Carbonization in the turbine area, which impairs the movement of the wheel assembly
(can be eliminated by axial movement).
– Dirt in the compressor area.
– Damage caused by foreign objects.
– Scraping of the turbine rotor on the housing.
If a considerable amount of dirt has accumulated, clean the compressor end and check the bearing
clearance.
Important! Do not damage the aluminium compressor wheel.