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

Symptom Tree  t022

This is symptom tree t022
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.


Coolant temperature gauge is malfunctioning

Test the temperature gauge. Repair or replace the gauge, if necessary. Refer to Procedure 008-004 and the OEM service manual.


Cold weather radiator cover or winterfront is closed

Open the cold weather radiator cover or the winterfront. Maintain a minimum of 784 cm2 [122 in2] or approximately 28 x 28 cm [11 x 11 in] of opening at all times. Refer to Operation of Diesel Engines in Cold Climates, Bulletin 3379009.


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.


Charge air cooler fins, radiator fins, or air conditioner condenser fins are damaged or obstructed with debris

Inspect the charge air cooler, air conditioner condenser, and radiator fins. Clean, if necessary. Refer to Procedures 010-027 and 008-042 and the OEM service manual.


Cooling system hose is collapsed, restricted, or leaking

Inspect the hoses. Refer to Procedure 008-045.


Fan drive belt is loose

Check the belt tension and tighten if necessary. Refer to Procedure 008-002.


Lubricating oil cooler is leaking

Check the lubricating oil cooler for coolant leaks. Refer to Procedure 007-003.


Lubricating oil level is above or below specification

Check the oil level. Add or drain oil if necessary. Refer to Procedures 007-025 and 007-009. Check the dipstick calibration.


Fan shroud is damaged or missing or the air recirculation baffles are damaged or missing

Inspect the shroud and the recirculation baffles. Repair, replace, or install, if necessary. Refer to Procedure 008-038 and the OEM service manual.


Radiator cap is not correct, is malfunctioning, or has low-pressure rating

Check the radiator pressure cap. Refer to Procedure 008-047.


Supplemental coolant additive (SCA) level is above specification or the coolant is overconcentrated with antifreeze

Check the SCA level. Verify the antifreeze concentration. Refer to Cummins Coolant Requirements and Maintenance, Bulletin 3666132.


Fill line or vent lines are restricted, obstructed, or not routed correctly

Check the vent lines and the fill line for correct routing and for restriction. Refer to Procedure 008-017 or the OEM specifications.


Intake manifold air temperature is above specification

Refer to the Intake Manifold Air Temperature Above Specification symptom tree.


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(s) 008-024, 008-025, 008-026, 008-027, or 008-028.


Thermostat is not correct or is malfunctioning

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


Air or combustion gases are entering the cooling system

Check for air or combustion gases in the cooling system. Refer to Procedure 008-019.


Cooling system component is malfunctioning

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


Radiator core is internally obstructed or damaged, or the check valve or J-tube is malfunctioning

Inspect the radiator and clean if necessary. Refer to Procedure 008-042.


Check valve is damaged (with remote-mounted engine coolant heater)

Inspect the check valve. Replace if necessary. Refer to the the manufacturer’s instructions.


Torque converter is malfunctioning

Check the torque converter. Refer to the OEM service manual.


Vehicle cooling system is not adequate

Verify that the engine and vehicle cooling systems are using the correct components. Refer to the OEM specifications.

Last Modified:  28-Mar-2005