Group 22 Service procedures - intake and exhaust systems
111
Boost pressure, checking
Special tools: 999 6065, 999 6591
1
Fit the connecting nipple 999 6591 and gauge 999 6065 to
the engine’s inlet manifold.
2
Measurement should occur continuously with a full load and
full acceleration, while the rpm slowly exceeds the speed lim-
its for the different engine types shown in “Workshop Manual,
Technical Data”.
The charging pressure should not fall below these levels.
Note: For this test to give a true picture of the situation, it is
essential that the full load condition is maintained a sufficient-
ly long period of time for the pressure to stabilize. It should
also be noted that boost pressure varies with the tempera-
ture of the intake air (ambient air).
If boost pressure is measured at any other temperature than
+25°C (+77°F), the boost pressure reading must be adjusted
by means of the diagram below.
Example:
A pressure of 100 kPa measured at 0°C is equivalent of 90
kPa at +25°C.
Boost pressure at different temperatures
A. Measured boost pressure
B. Correction curves
C. Temperature of intake air
Service procedures
The engine must always be washed prior to starting repairs.
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