3512C Marine Auxiliary Generator Set Engines with Dynamic Gas Blending Caterpillar

Exhaust Temperature Is Low

Usage:

Use this procedure in order to troubleshoot an occurrence of a low exhaust temperature. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.

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Table 1
Diagnostic Codes Table
J1939 Code and Description	Conditions which Generate this Code	System Response
5686-1 Engine Exhaust Gas Port #1 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5687-1 Engine Exhaust Gas Port #2 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5688-1 Engine Exhaust Gas Port #3 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5689-1 Engine Exhaust Gas Port #4 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5690-1 Engine Exhaust Gas Port #5 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5691-1 Engine Exhaust Gas Port #6 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5692-1 Engine Exhaust Gas Port #7 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5693-1 Engine Exhaust Gas Port #8 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5694-1 Engine Exhaust Gas Port #9 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5695-1 Engine Exhaust Gas Port #10 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5696-1 Engine Exhaust Gas Port #11 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.
5697-1 Engine Exhaust Gas Port #12 Difference from Average Temperature : Low - most severe (3)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged. The engine is shut down.

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Table 2
Diagnostic Codes Table
J1939 Code and Description	Conditions which Generate this Code	System Response
5686-17 Engine Exhaust Gas Port #1 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5687-17 Engine Exhaust Gas Port #2 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5688-17 Engine Exhaust Gas Port #3 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5689-17 Engine Exhaust Gas Port #4 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5690-17 Engine Exhaust Gas Port #5 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5691-17 Engine Exhaust Gas Port #6 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5692-17 Engine Exhaust Gas Port #7 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5693-17 Engine Exhaust Gas Port #8 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5694-17 Engine Exhaust Gas Port #9 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5695-17 Engine Exhaust Gas Port #10 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5696-17 Engine Exhaust Gas Port #11 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.
5697-17 Engine Exhaust Gas Port #12 Difference from Average Temperature : Low - least severe (1)	The cylinder exhaust temperature is lower than the average temperature for all of the cylinders. The amount of deviation has exceeded the trip point for the programmed delay time.	The code is logged.

If the engine is shut down due to a low exhaust temperature, the power to the engine Electronic Control Module (ECM) must be cycled in order to restart the engine.

Probable Causes

Monitoring system parameters
Inlet air restriction
Cylinder misfire
Faulty thermocouple
Valve lash settings
Low cylinder compression

Recommended Actions

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Table 3
Troubleshooting Test Steps	Values	Results
1. Check for Active Codes and Logged Codes A. Connect Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools", if necessary. B. Download the "Product Status Report" from the engine ECM before performing any troubleshooting or clearing diagnostic trouble codes. C. Determine if the diagnostic trouble code that directed to this procedure is present. D. Look for active diagnostic codes that are associated with the system for the event code that directed to this procedure.	Codes	Result: A code is active or logged. Repair: Troubleshoot any associated codes before continuing with this test. Result: A code is present for an exhaust port temperature. Proceed to Test Step 2. Result: A code is not active or logged. STOP
2. Check the Monitoring System Parameters A. Ensure that the monitoring system parameters for the exhaust temperature module are set correctly. B. Ensure that the monitoring system parameters for the exhaust port temperatures are set correctly.	Parameters	Result: The module parameters are OK. Continue with this step. Result: The module parameters are NOT OK. Repair: Refer to Troubleshooting, "Diagnostic Codes" for information that relates to the default parameters, ranges, and delay times of the monitoring system parameters that are for the exhaust port temperatures. Result: The port temperatures parameters are OK. Proceed to Test Step 3. Result: The port temperatures parameters are NOT OK. Repair: Refer to Troubleshooting, "Diagnostic Codes" for information that relates to the default parameters, ranges, and delay times of the monitoring system parameters that are for the exhaust port temperatures. Verify that the repair eliminated the problem.
3. Check for Inlet Air Restriction Note: Inlet air restriction can cause uneven exhaust port temperatures. Cylinders at the front half of the engine may have exhaust port temperatures that are lower than the exhaust port temperatures for the cylinders at the rear half of the engine by 10 to 20 °C (18 to 36 °F). A. Measure the inlet air restriction for each turbocharger.	Restriction	Result: The inlet air restriction is OK. Proceed to Test Step 4. Result: The inlet air restriction is NOT OK. An imbalance in the system is discovered. Repair: Equalize the inlet air restriction for each of the turbochargers. Verify that the repair eliminated the problem.
4. Check for Operation with a Light Load Note: Operation with a low load can result in low exhaust temperatures. A. Operate the engine at low idle or near low idle in order to detect a misfire problem.	Misfire	Result: There is a misfire. Repair: Troubleshoot the cause of the misfire. Refer to Troubleshooting, "Engine Misfires, Runs Rough or Is Unstable". Result: There is not a misfire. Proceed to Test Step 5.
5. Check for Faulty Thermocouples A. Observe the temperatures from the thermocouples after the engine is shut off. When the engine is operating properly, the temperatures from similar locations are reduced at a similar rate. Also, the temperatures from similar locations are comparable.	Thermocouples	Result: The thermocouples are OK. Proceed to Test Step 6. Result: The thermocouples are NOT OK. Repair: Switch the suspect thermocouple for another thermocouple. If the temperature problem follows the thermocouple, replace the suspect thermocouple. If the temperature problem stays at the original location of the suspect thermocouple, investigate the cause for the low temperature. Verify that the repair eliminated the problem.
6. Check the Valve Lash Settings A. Check the valve lash settings for the valves on the engine. Refer to Systems Operation/Testing and Adjusting, "Valve Lash - Adjust" for information that is related to adjusting the valve lash for the engine.	Valve Lash	Result: The valve lash is OK. Proceed to Test Step 7. Result: The valve lash is NOT OK. Repair: Reset valve lash. Refer to Systems Operation/Testing and Adjusting, "Valve Lash - Adjust" for information that is related to adjusting the valve lash for the engine. Verify that the repair eliminated the problem.
7. Check for Low Cylinder Compression A. Measure the cylinder pressures of the suspect bank in order to check for problems that are related to compression.	Compression Check	Result: The cylinder pressure is NOT OK. Investigate the cause of the low compression. Repair: Repair or replace as necessary.

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).