GEAR 1351593 - Caterpillar

The efficiency of an engine can be checked. Compare the pressure in the inlet manifold with the specifications that are given in the Fuel Setting and Related Information in the TMI (Technical Marketing Information). This test is performed when there is a decrease in the horsepower from the engine yet there is no real sign of a problem with the engine.The correct pressure for the inlet manifold is given in the TMI. Development of this information is done with these conditions:
96 kPa (28.8 inches of Hg) dry barometric pressure
29 °C (84 °F) outside air temperature
35 API rated fuelAny change from these conditions can change the pressure in the inlet manifold. The outside air may have a higher temperature and a lower barometric pressure than the values that are given above. This will cause a lower horsepower and a lower inlet manifold pressure measurement than the pressure that is given in the TMI (Technical Marketing Information). Outside air that has a lower temperature and a higher barometric pressure will cause a higher horsepower and a higher inlet manifold pressure measurement.A difference in the fuel rating will change the horsepower in the inlet manifold and the pressure in the inlet manifold. If the fuel is rated above 35 API, the pressure in the inlet manifold can be less than the pressure that is given in the TMI. If the fuel is rated below 35 API, the pressure in the inlet manifold can be more than the pressure that is given in the TMI. When you are checking the pressure in the inlet manifold, be sure that the air inlet or the exhaust is not restricted.
Illustration 1 g00322855
Pressure test location (typical example)
(A) Pipe plug In order to check the inlet manifold pressure, remove the 1/2-14-NPTF pipe plug (A). Connect the 1U-5470 Engine Pressure Group to this opening in the inlet manifold.This tool group has a gauge to read pressure in the inlet manifold. Refer to Special Instruction, SEHS8524 for further instructions.
Illustration 2 g00284796
1U-5470 Engine Pressure Group
(1) Pressure indicators
(2) Zero adjustment screw
(3) Pressure indicator
(4) Pressure tap
(5) Pressure indicator