THERMOCOUPLE 1141653 - Caterpillar

Probable Causes
Coolant temperature sensor circuit
Low coolant temperature
Glow plugs
Fuel quality
Valve lash
Low compression (cylinder pressure)
Individual malfunctioning cylinderRecommended Actions
Coolant Temperature Sensor Circuit
Connect the electronic service tool to the diagnostic connector.
Monitor the display screen on the electronic service tool in order to verify the presence of active diagnostic codes for the coolant temperature. Refer to Troubleshooting, "Engine Temperature Sensor Open or Short Circuit - Test".
If the fault has not been eliminated, proceed to "Low Coolant Temperature". Low Coolant Temperature
Check that the water temperature regulator is operating correctly. Refer to Systems Operation, Testing and Adjusting, "Water Temperature Regulator - Test".If the water temperature regulator is operating correctly, refer to "Glow Plugs".Glow Plugs
Check for correct operation of the glow plugs. Refer to Systems Operation, Testing and Adjusting, "Glow Plugs - Test".
If the repairs do not eliminate the fault refer to "Fuel Quality". Fuel Quality
Check the diesel fuel for quality. Refer to Systems Operation, Testing and Adjusting, "Fuel Quality - Test". Note: Diesel fuel with a low cetane value is likely to cause white smoke.
If the repair does not eliminate the fault refer to "Valve Lash". Valve Lash
Ensure that the valve lash is correct. Refer to Systems Operation, Testing and Adjusting, "Engine Valve Lash - Inspect/Adjust".
If the repair does not eliminate the fault proceed to "Low Compression (cylinder pressure)". Low Compression (cylinder pressure)
Perform a compression test. Refer to Systems Operation, Testing and Adjusting, "Compression - Test ".
If low compression is noted on any cylinders, investigate the cause and rectify the cause. Possible causes of low compression are shown in the following list:
Loose glow plugs
Faulty piston
Faulty piston rings
Worn cylinder bores
Worn valves
Faulty cylinder head gasket
Damaged cylinder head
Perform all necessary repairs.
Ensure that the repair has eliminated the fault.
If the repair does not eliminate the fault refer to "Individual Malfunctioning Cylinder". Individual Malfunctioning Cylinder
With the engine speed at a fast idle, use the electronic service tool to isolate one cylinder at a time. Note if there is any reduction in engine speed. If a reduction in engine speed is not noted, the isolated cylinder is not operating under normal conditions. If the isolation of a particular cylinder results in a reduction of engine speed that is less than normal, this may indicate that the cylinder is operating below normal performance. Investigate the cause of the fault on any cylinder that is not operating. Investigate the cause of the fault on any cylinder that is operating below normal performance.
Rectify any faults.
If the fault has not been eliminated, repeat this test procedure from Test Step 1.