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C-15 and C-16 Industrial Engines – Inlet Manifold Pressure – Test

Table 1
Tools Needed    
Part Number     Part Name     Quantity    
1U-5470     Engine Pressure Group     1    

The efficiency of an engine can be checked by making a comparison of the pressure in the inlet manifold with the information given in the TMI (Technical Marketing Information) or Microfiche, “Fuel Setting And Related Information”. This test is used when there is a decrease of horsepower from the engine, yet there is no real sign of a problem with the engine.

The correct pressure for the inlet manifold is listed in the TMI (Technical Marketing Information) or Microfiche, “Fuel Setting And Related Information”. Development of this information is performed under the following conditions:

  • 99 kPa (29.7 in Hg) dry barometric pressure

  • 29 °C (85 °F) outside 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 (Technical Marketing Information) or Microfiche, “Fuel Setting And Related Information”. If the fuel is rated below 35 API, the inlet manifold pressure can be more than the pressure listed in the TMI (Technical Marketing Information) or Microfiche, “Fuel Setting And Related Information”.

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 following procedure in order to use an electronic service tool to measure the inlet manifold pressure:

  1. Connect the electronic service tool.
  1. Operate the engine under the suspect conditions.
  1. Record the value.
  1. Compare the value that was recorded in Step 3 to the pressure that is given in the TMI (Technical Marketing Information) or Microfiche, “Fuel Setting And Related Information”.

Use the following procedure in order to use the 1U-5470 Engine Pressure Group to measure the inlet manifold pressure:

    Illustration 1 g00298478

    Pressure test location on the inlet manifold

    (1) Inlet manifold air temperature sensor

    (2) Pipe plug

    (3) Boost pressure sensor



    Illustration 2 g00293196

    1U-5470 Engine Pressure Group

  1. Remove pipe plug (2) from the inlet manifold. It is not necessary to remove inlet manifold air temperature sensor (1). It is not necessary to remove boost pressure sensor (3) .
  1. 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 information on using the tool.

  1. Operate the engine under the suspect conditions.
  1. Record the value.
  1. Compare the value that was recorded in Step 4 to the pressure that is given in the TMI (Technical Marketing Information) or Microfiche, “Fuel Setting And Related Information”.