
38 RENR9968-02
Testing and Adjusting Section
i02227890
Inlet Manifold Pressure - Test
SMCS Code: 1058-081
Table 5
Required Tools
Part
Number
Part Name
Quantity
1U-5470
or
198-4240
Engine Pressure Group
or
Digital Pressure Indicator
1
The efficiency of an engine can be checked by
making a compar
ison of the pressure in the inlet
manifold with the information given in the Technical
Marketing Inform at ion (TMI). This test is us ed when
there is a decr
ease of horsepower from the engine,
yet there is no real sign of a problem with the engine.
The correct pr
essure for the in le t manifold is liste d
in the TMI. D evelopment of this information is
performed under the following conditions:
•
99 kPa (2 9. 7 in Hg) dry ba rometric pressu re
•
29 °C (85 °F) o
utside air temperature
•
35 API rated fuel
On a turbocharged, aftercooled engine, a change
in the fuel rating will change the horsepower. A
change in the
fuel rating will change the inlet manifold
pressure. If the fuel is rated above 35 API, the inlet
manifold pressure can be less than the pressure
given in the
TMI. If the fuel is rated below 35 API,
the inlet manifold pressure can be more than the
pressurelistedintheTMI.
Note: Ensure that the air inlet and the exhaust are
not restricted when you check the inlet manifold
pressure.
Refer to Testing and Adjusting, “Air Inlet
and Exhaust System - Inspect” for more information.
Use the fol
lowing procedure in order to use an
electronic service tool to measure the inlet manifold
pressure:
1. Connec t th e Caterpillar Electronic Technician (ET).
2. Operate th
e engine under the suspect conditions.
3. Record the value.
4. Compare the value t hat was recorded in Step 3 to
thepressurethatisgivenintheTMI.
Use the following procedure in order to use the
1U-5470 Engine Pressure Group to me asure the
inlet manifold pressure:
g00293196
Illustration 30
1U-5470 Engine Pressure Group
1. Remove the pip e plug from t he inlet manifold. It
is not necessary to remove the air temperature
sensor from the inlet manifold.
2. Connect the 1U-5470 Engine Pressure Group to
the inlet manifold at the pressure test location.
Refer to Special Instruction, SEHS8907, “Using
the 1U-5470 Engine Pressure Group” for more
informationonusingthetool.
3. Operate the engine under the suspect conditions.
4. Record the value.
5. Compare the value tha t was recorded in Step 4 to
the press ure t ha t is given in the TMI.
i02387243
Exhaust Temperature - Test
SMCS Code: 1088-081
Ta b l e 6
Required Tools
Part
Number
Part Name Qty
164-3310
Infrared Thermometer
1
When the engine runs at low idle, the temperature of
an exhaus
t m anifold port can indicate the condition
of a fuel injection nozzle.
Alowtemp
erature indicates that no fuel is flowing to
the cylinder. An inoperative fuel injection nozzle or
a p roblem with the fuel injection pump could cause
this low t
emperature.