BOLT 9S2727 - Caterpillar

Use this procedure to troubleshoot a low coolant pressure. Also, use this procedure if one of the following event codes is active or logged.
Table 1
J1939 Code and Description Comments
109-1
Engine Coolant Pressure : Low - most severe (3) The engine coolant pressure is below the map-based trip point pressure for the programmed delay time.
The fuel is shut off.
The code is logged.
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) The engine coolant pressure is below the map-based trip point pressure for the programmed delay time.
The code is logged. Probable Causes
Codes
Coolant level
Leaks
Sensor
Water pump
Heat exchanger
Oil coolerRecommended Actions
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 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: Add coolant. Determine the cause of the low coolant level.
If the problem is not resolved, proceed to Test Step 3.
3. Check the Cooling System for Damaged Lines
A. Inspect the lines for the following conditions:
- Damage
- Crushing
- Bending
B. Inspect the rubber boots for the following:
- Cracks
- Collapsed
Leaks
Result: The cooling system lines are OK.
Proceed to Test Step 4.
Result: The cooling system lines are NOT OK.
Repair: Repair or replace any damaged cooling system lines or components.
If the problem is not resolved, proceed to Test Step 4.
4. 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 ET.
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 5.
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 5.
5. 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 6.
Result: There was