C175 Tier 4 Final Engines for Off-Highway Trucks Caterpillar

Coolant Pressure Is Low

Usage:

793F D3T

Use this procedure to troubleshoot a low coolant pressure. Also, use this procedure if one of the following event codes is active or logged.

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Table 1
J1939 Code and Description	CDL Code and Description	Comments
N/A	E563 (3) Low Engine Coolant Flow	The Electronic Control Module (ECM) detects that the coolant flow through the engine is lower than expected.
N/A	1937-2 Engine Coolant Flow Switch : Erratic, Intermittent, or Incorrect	The ECM detects that the coolant flow through the engine is different than expected.
109-1 Engine Coolant Pressure : Low - most severe (3)	E2112 (3) Low Engine Coolant Pressure	The engine coolant pressure is lower than expected for an extended period. The code is logged.
109-17 Engine Coolant Pressure : Low - least severe (1)	E2112 (1) Low Engine Coolant Pressure	The engine coolant pressure is lower than expected for an extended period. The code is logged.
109-18 Engine Coolant Pressure : Low - moderate severity (2)	E2112 (2) Low Engine Coolant Pressure	The engine coolant pressure is lower than expected for an extended period. The code is logged.

Probable Causes

Codes
Coolant level
Leaks
Expansion tank (if equipped)
Sensor
Flow switch
Water pump
Radiator
Oil cooler

Recommended Actions

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check for Codes A. Connect Cat^® Electronic Technician (ET) to the service tool connector. B. Look for active codes that are associated with the system for the event code.	Codes	Result: An associated code is active. Repair: Troubleshoot any associated codes before continuing with this test. Result: A code is active or logged. Proceed to Test Step 2.
2. Check the Coolant Level Note: If the coolant level is too low, air will get into the cooling system. Air in the cooling system will cause a reduction in coolant flow and pressure. A. Check the cooling system for coolant leaks.	Coolant Level	Result: The coolant level is OK. Proceed to Test Step 3. Result: The coolant level is NOT OK. Repair: Determine the cause of the low coolant level. Refer to Troubleshooting, "Coolant Level Is Low" for additional information. If the problem is not resolved, proceed to Test Step 3.
3. Check the Cooling System Hose Routing A. Check the cooling system clamps and hoses to make sure that the clamps and hoses are installed in the proper location and the clamps are tight. B. Ensure that there are no kinks or tight bends that may cause excessive restriction. C. Check to make sure that the hoses are routed correctly.	Leaks or Kinks	Result: The coolant clamps and hoses are installed properly. Proceed to Test Step 4. Result: The coolant clamps and hoses are not installed properly. Repair: Repair or replace the damaged cooling system component. If the problem is not resolved, proceed to Test Step 4.
4. Check the Expansion Tank A. Check the shunt line for a restriction. A restriction of the shunt line from the expansion tank to the inlet of the jacket water pump will cause a reduction of water pump efficiency. B. Inspect the expansion tank for a restriction that blocks the port to the shunt line. Note: The expansion tank may be integrated into the design of the radiator top tank and may not be separate.	Shunt Line	Result: The shunt line is properly installed and there are no restrictions. For a E2112 or 109 code, proceed to Test Step 5. For a E563 or 1937 code, proceed to Test Step 6. Result: The shunt line is not properly installed or there are restrictions. Repair: Install the shunt line correctly or replace the line if necessary. Remove any restrictions that are found. If the problem is not resolved, proceed to Test Step 5.
5. Check the Coolant Pressure Sensor A. Install a mechanical pressure gauge in the coolant jacket near the coolant pressure sensor. B. Start the engine. C. Connect Cat^® Electronic Technician (ET) to the service tool connector. D. Allow the engine to run and record the coolant pressure on the mechanical gauge. E. Check the coolant pressure reading at various engine speeds.	Sensor	Result: The pressure difference between the mechanical gauge and the reading in Cat ET is less than 14 kPa (2 psi). Proceed to Test Step 7. Result: The pressure difference between the mechanical gauge and the reading in Cat ET is greater than 14 kPa (2 psi). Repair: Replace the coolant pressure sensor. If the problem is not resolved, proceed to Test Step 7.
6. Check the Coolant Flow Switch A. Remove the coolant flow switch from the engine. B. Turn the keyswitch to the ON position. C. Connect Cat ET. D. Rotate the paddle on the end of the coolant flow switch. E. Use Cat ET to monitor the following switch: - Coolant flow switch	Flow Switch	Result: The coolant flow switch status changed in Cat ET when the paddle was rotated. Proceed to Test Step 7. Result: The coolant flow switch status did not change in Cat ET when the paddle was rotated. Repair: A failed coolant flow switch has been detected. Replace the coolant flow switch. If the problem is not resolved, proceed to Test Step 7.
7. Inspect the Water Pump A. Inspect the impeller of the water pump for damage or erosion. B. Ensure that the drive gear is not loose on the drive shaft of the water pump.	Water Pump	Result: The water pump is OK. Proceed to Test Step 8. Result: There was a problem with the water pump. Repair: Repair or replace damaged water pump components. If the problem is not resolved, proceed to Test Step 8.
8. Check the Radiator for Problems A. Check the cooling fins on the radiator for dirt and for debris. B. Check for sufficient flow and temperature of the cooling water through the radiator. C. Ensure that the size of the radiator is sufficient.	Radiator	Result: The radiator is OK. Proceed to Test Step 9. Result: A problem with the radiator has been discovered. Repair: If the temperature of the cooling water is too high, determine the cause. Clean the components or replace the radiator. If the problem is not resolved, proceed to Test Step 9.
9. Check the Oil Cooler for a Restriction A. Check the inlet side of the oil cooler for debris or blockage.	Restrictions	Result: There was debris or restrictions in the oil cooler. Repair: Clean or replace the oil cooler. 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).