C175-16 Locomotive Engine Caterpillar

Aftercooler Coolant Temperature Is High

Usage:

Use this procedure in order to troubleshoot a high aftercooler coolant temperature or use this procedure if one of the following event codes is active. Refer to Troubleshooting, "Event Codes" for information about event codes.

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Table 1
Event Code
Code and Description	Conditions which Generate this Code	System Response
E771(1) High Aftercooler Temperature	The aftercooler coolant temperature is above the trip point pressure for the programmed delay time.	The code is logged.
E771(2) High Aftercooler Temperature		The code is logged. The engine is derated.
E771(3) High Aftercooler Temperature		The code is logged. The engine is shut down.

If the engine is shut down due to a high aftercooler temperature, the power to the engine ECM must be cycled in order to restart the engine.

Probable Causes

Diagnostic codes and event codes
Low coolant level for the Separate Circuit Aftercooler system (SCAC)
SCAC Radiator
Leakage in the SCAC system
Damage to the piping for the SCAC system
Cooling fan for the SCAC system
Pressure cap for the radiator
SCAC water pump
Engine load

Recommended Actions

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for 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.	E771	Result: An associated code is present. Repair: Troubleshoot any associated codes before continuing with this test. Result: An E771 code is present. Proceed to the next step. Result: No active codes STOP
2. Check for Low Coolant Level for the Separate Circuit Aftercooler System (SCAC) A. Inspect the coolant level.	Coolant level	Result: The coolant level is OK. Proceed to the next step. Result: The coolant level is NOT OK. Repair: Add coolant. If the problem is not resolved, proceed to the next step.
3. SCAC Radiator A. Check the cooling fins on the radiator for dirt and/or for debris. B. Check the cooling fins on the radiator for damage. C. Check the radiator for internal blockage. Check the temperature difference between the inlet and the outlet of the radiator.	Radiator	Result: The cooling fins are clean. Continue with this step. Result: The cooling fins are not clean. Repair: Remove dirt and/or debris. Result: The cooling fins are damaged. Repair: Refer to the Systems Operation/Testing and Adjusting manual for instructions for testing and inspecting the cooling system. Result: The cooling fins are not damaged. Continue with this step. Result: The scac radiator has an internal blockage. Repair: Clean the scac radiator or perform the necessary repairs. Result: The scac radiator does not have an internal blockage If the problem is not resolved, proceed to the next step.
4. Look for SCAC System Leakage A. Check the cooling system for leaks. 1. Inspect the coolant for presence of bubbles. Note: Cavitation will reduce the efficiency of the cooling system.	Leak	Result: The cooling system is OK. Proceed to the next step. Result: The cooling system is NOT OK. Repair: Repair the cooling system. If the problem is not resolved, proceed to the next step.
5. Look for Damage to the Piping for the SCAC System Note: Damaged piping can restrict the flow of coolant to the aftercooler core. A. Perform a visual inspection of the piping for the SCAC system. Look for piping that is: - Damaged - Crushed - Bent	Damaged piping	Result: The SCAC piping is OK. Proceed to the next step. Result: The piping is damaged NOT OK. Repair: Repair or replace the damaged piping. If the problem is not resolved, proceed to the next step.
6. Check the Cooling Fan for the SCAC System A. Check for proper operation of the cooling fan for the SCAC system.	Fan	Result: The cooling fan is OK. Proceed to the next step. Result: The cooling fan is not OK. Repair: Repair the fan or replace the fan. If the problem is not resolved, proceed to the next step.
7. Check the Pressure Cap for the Radiator A. Check the operation of the pressure relief valve and the radiator cap for the SCAC radiator.	Relief Valve	Result: The pressure relief valve is OK. Result: The pressure relief valve is NOT OK. Repair: If necessary, clean the seal and the seating surface in the cap. Check that the seating surface on the fill neck of the radiator is clean and undamaged. If the sealing components of the pressure cap are suspect, replace the cap.
8. Inspect the SCAC Water Pump A. Inspect the impeller vanes of the water pump for damage and/or for erosion.	Damaged vanes	Result: The impeller vanes are OK. Proceed to the next step. Result: The impeller vanes are NOT OK. Repair: Repair or replace the pump.
9. Check for Engine Overload A. Determine if the engine is being overloaded. NOTE: When the engine is running in the lug condition, engine rpm does not increase with an increase of fuel. The lug condition can cause high cylinder temperatures. High cylinder temperatures can cause a high coolant temperature.	Load	Result: The engine is not being overloaded. Result: The engine is being overloaded. Repair: Reduce engine load to an acceptable limit.