3516B and 3516C Engines For MT4400D AC Off-Highway Trucks Caterpillar

Use this procedure in order to troubleshoot low engine coolant pressure. Also, use this procedure if the following event code is active.

Table 1

Event Code
Code and Code Description	Conditions which Generate this Code	System Response
109-17 Engine Coolant Pressure : Low - least severe (1)	The engine coolant pressure is below the map-based trip point pressure for the programmed delay time.	The code is logged.
109-18 Engine Coolant Pressure : Low - moderate severity (2)
109-1 Engine Coolant Pressure : Low - most severe (3)
E2112(1) Low Engine Coolant Pressure - least severe	The engine coolant pressure is below the map-based trip point pressure for the programmed delay time.	The code is logged.
E2112(2) Low Engine Coolant Pressure - moderate severity
E2112(3) Low Engine Coolant Pressure - most severe

Probable Causes

• Low coolant level

• Damaged coolant lines

• Radiator blockage

• Blockage of the oil cooler heat exchanger

• Engine coolant pump outlet pressure sensor

• Jacket water coolant pump

Recommended Actions

Table 2

Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Establish communication between Caterpillar Electronic Technician (ET) and the Electronic Control Module (ECM). 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 diagnostic code is present. Repair: Troubleshoot any codes before continuing with this procedure. Verify that the repair eliminated the problem. Result: A 109-18 code is present. Proceed to Test Step 2. Result: No active codes STOP
2. Check for Low Coolant Level	Level	Result: Coolant level is OK. Proceed to Test Step 3. Result: Coolant level is NOT OK. Repair: Add coolant. Verify that the repair eliminated the problem.
3. Check for Damaged Cooling System Piping A. Inspect the piping for the following conditions: - Damage - Crushing - Bending B. Inspect the rubber boots: Look for signs of cracking, and collapse.	Damage	Result: The system piping is OK. Proceed to Test Step 4. Result: The system piping is NOT OK. Repair: Repair or replace any damaged piping or boots. Verify that the repair eliminated the problem.
4. Inspect the Radiator for Blockage A. Check the radiator for internal blockage. B. Check the temperature difference between the inlet and the outlet of the radiator.	Blockage	Result: The radiator is OK. Proceed to Test Step 5. Result: The radiator is NOT OK. Repair: Clean the radiator or perform the necessary repairs. Verify that the repair eliminated the problem.
5. Check if the Oil Cooler has a Blockage A. Inspect the inlet side of oil cooler for debris and blockage.	Blockage	Result: The oil cooler is OK. Proceed to Test Step 6. Result: The oil cooler is NOT OK. Repair: Clean the oil cooler or perform the necessary repairs. Verify that the repair eliminated the problem.

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Steam or hot coolant can cause severe burns. Do not loosen the filler cap or the pressure cap on a hot engine. Allow the engine to cool before removing the filler cap or the pressure cap.

Table 3

Troubleshooting Test Steps	Values	Results
6. Check the Engine Coolant Pump Outlet Pressure Sensor A. While the engine is off and the cooling system is cool, remove any pressure from the system by carefully removing the pressure cap. B. Compare the "Engine Coolant Pump Outlet Pressure (Absolute)" to the status of the "Atmospheric Pressure" parameter.	Sensor	Result: For sensors that are working correctly, the pressures will be comparable. The sensor is OK. Proceed to Test Step 7. Result: The sensor is NOT OK. Repair: Replace the damaged components. Refer to the Disassembly and Assembly manual. Verify that the repair eliminated the problem.
7. Install a Mechanical Gauge to Verify the Coolant Pressure A. Install a mechanical gauge near the coolant pressure sensor. B. Use the gauge to verify that a low coolant pressure exists.	Mechanical Gauge	Result: The mechanical gauge does not confirm that the coolant pressure is low. Repair: Troubleshoot the circuit for the coolant pressure sensor. Verify that the repair eliminated the problem. Result: The mechanical gauge confirms that the coolant pressure is low. Perform the following checks: - Check the water temperature regulators for proper operation. - Check for a plugged heat exchanger. - Inspect the coolant pump for damage to the impeller. Repair: Perform any necessary repairs. Verify that the repair eliminated the problem.
8. Inspect the Jacket Water Coolant Pump A. Inspect the impeller vanes.	Pump	Result: The pump is OK. Result: The pump is NOT OK. Repair: Repair impeller vanes. Replace parts, if necessary. Refer to the engine Disassembly and Assembly manual for details. Verify that the repair eliminated the problem.

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).