CAP 5434995 - Caterpillar

High Inlet Air Restriction and/or High Altitude
Check for plugged air filters. Check for obstructions to the air inlet. When inlet air pressure is low, the turbocharger works harder in order to achieve the desired inlet manifold pressure. This increases inlet air temperature.Measure the inlet air pressure while the engine is operating under load. For specific data, refer to the Technical Marketing Information for the engine.Make sure that the settings for the engine are correct for the altitude.Temperature Sensor and/or Circuit
Use an electronic service tool to check reading for the inlet air temperature. Ensure that the temperature is reasonable.Allow the sensor to cool and remove the sensor. Check the reading for the inlet air temperature again. If the sensor is OK, the reading and the ambient temperature are approximately equal.If the reading is not correct, troubleshoot the circuit for the sensor. Refer to Electronic Troubleshooting, SENR6517, "Inlet Manifold Temperature Sensor".Coolant Temperature
Refer to "High Coolant Temperature".Aftercooler Water
Check the inlet temperature of the coolant for the aftercooler. Compare the reading to the regulated temperature. If the temperature is OK, check the outlet temperature of the coolant. A high temperature differential indicates an insufficient flow rate.If there is a high differential between the inlet temperature and the outlet temperature of the coolant for the aftercooler, perform the following procedures:
Check the water circuit of the aftercooler for obstructions.
Check the pump for proper operation.
Make repairs, if necessary.Aftercooler's Air
Determine the pressure differential of the inlet air across the aftercooler. For specific data, refer to the Technical Marketing Information for the engine.If the pressure differential of the air across the aftercooler does not match the specifications, clean the aftercooler.High Exhaust Temperature
Probable Causes
High inlet manifold air temperature
Inlet air restriction
Exhaust restriction
Incorrect ignition timing
Incorrect air/fuel ratio
Excessive load
Deposits in the cylinderRecommended Repairs
Inlet Manifold Air Temperature
High inlet manifold air temperature can increase exhaust temperatures. Also, detonation can occur. Check the inlet manifold air temperature.Refer to "High Inlet Air Temperature".Inlet Air Restriction
The maximum allowable inlet air restriction is 3.75 kPa (15 inches of H2O). If the indication is higher than the maximum permissible restriction, clean the filter element or install a new filter element. Check the restriction again. If the restriction remains too high, inspect the air inlet piping before the air cleaner for obstructions.Exhaust Restriction
The maximum allowable exhaust restriction is 6.7 kPa (27 inches of H2O). Check for restriction in the exhaust system.If the difference between the pressure at the exhaust elbow and the atmospheric pressure exceeds the specification, determine the cause. Make the necessary repairs.Ignition Timing
Note: Data from a fuel analysis is required for this procedure.Use an electronic service tool to check for the correct desired ignition timing. Refer to Electronic Troubleshooting, SENR6413. Compare the timing to the recommended timing in the Engine Performance, "Fuel Usage Guide".Adjust the ignition timing according to the recommended timing in the Engine Performance, "Fuel Usage Guide".Air/Fuel Ratio
An air/fuel mixture that is too rich will increase the exhaust temperature. A change in the fuel energy content will change the air/fuel ratio. Obtain a fuel analysis.The