Checking The Charge-Air Pressure - Man D 2842 LE 620 Repair Manual

Sufficient charge-air pressure is indispensable for full power output and clean combustion.
The check is designed to ascertain whether damage to the turbocharger and leaks in the intercooler and in
the charge-air pipes have occurred.
Extreme operating conditions (full-load operation and high air temperature) and the use of unsuitable en-
gine oils (also see publication "Fuels, Lubricants, Coolants for MAN Diesel Engines") may cause deposits
on the compressor as well as in the intercooler, which results in a reduction in charge-air pressure.
Preconditions for the measurement:
The delivery start and the valve clearance must be set as specified, and the engine must be at operating
temperature.
Charge-air pressure:
A general set-point value for charge-air pressure cannot be given, as the installation conditions have a
bearing on this.
The value ascertained during the commissioning of the engine and noted in the commissioning report is to
be used as the set-point value.
When carrying out the measurement, observe the following:
Owing to various atmospheric reference conditions during the measurements and to tolerances of the pres-
sure gauges used, deviations of max. ± 100 hPa (± 100 mbar) are permissible.
Fig. 1
The measuring connection for checking the
charge-air pressure and the charge-air tempera-
ture is located in the intake pipe at the point where
the flame-starter sheathed-element glow plug is
screwed in.
Remove flame-starter sheathed-element glow
plug, see page 39.
Connect up pressure gauge (if necessary using a
suitable threaded pipe as adapter).
Fig. 2
Measure the charge-air pressure downstream of
the intercooler at nominal engine speed and full
load.

Checking the charge-air pressure

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