ISM, ISMe, and QSM11 – Coolant Temperature Above Normal – Sudden Overheat

Symptom Tree  t023

This is symptom tree t023
Cause Correction

Electronic fault codes active or high counts of inactive fault codes

View and troubleshoot the fault codes with INSITE™. Refer to Section TF in the Troubleshooting and Repair Manual, Electronic Control System, ISM and QSM11 Engines, Bulletin 3666266 or the Troubleshooting and Repair Manual, CM870 Electronic Control System ISM Engines, Bulletin 4021381.


Fan drive belt is broken

Check the fan drive belt. Replace the belt, if necessary. Refer to Procedure 008-002.


Coolant level is below specification

Inspect the engine and cooling system for external coolant leaks. Repair if necessary. Add coolant. Refer to Procedure 008-018.


Coolant level is below specification

Inspect engine for internal coolant leaks. Refer to the Coolant Loss – Internal symptom tree.


Cooling system hose is collapsed, restricted, or leaking

Inspect the radiator hoses. Refer to Procedure 008-045.


Radiator shutters are not opening completely or the shutterstat setting is wrong

Inspect the radiator shutters. Repair or replace if necessary. Refer to the manufacturer’s instructions. Check the shutterstat setting. Refer to Procedure 008-020 or 008-049.


Fan drive or fan controls are malfunctioning

Check the fan drive and controls. Refer to Procedure 008-024, 008-025, 008-026, 008-027, or 008-028.


Cooling system component is malfunctioning

Perform the cooling system diagnostics test. Refer to Procedure 008-020.


Thermostat is not correct or is malfunctioning

Check the thermostat for the correct part number and for correct operation. Refer to Procedure 008-013.

Last Modified:  16-Jan-2004