Cummins ISX11.9 CM2250 – Service Manual Coolant Temperature Above Normal – Sudden Overheat

Coolant level is below specification

Check the coolant level. Check for an external leak. Refer to
Procedure 008-018 in Section 8
. Sample the lubricating oil and have a laboratory check for coolant in the oil (internal leak).

Electronic fault codes active or high counts of inactive fault codes

Refer to Section TF in the Fault Code Troubleshooting Manual, Bulletin
4022225.

Fan drive belt is broken

Check the fan drive belt. Replace the belt, if necessary. Refer to Procedure 008-002 in Section 8.

Fan drive or fan controls are malfunctioning

Check the fan drive and controls. Refer to
Procedure 008-027 in Section 8
.

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

Inspect the radiator shutters. Repair or replace if necessary. Check the shutterstat setting. Refer to
Procedure 008-049 in Section 8
.

Cooling system hose is collapsed, restricted, or leaking

Inspect the hoses. Refer to
Procedure 008-045 in Section 8
.

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

Check the radiator pressure cap. Refer to
Procedure 008-047 in Section 8
.

Thermostat is not correct or is malfunctioning

Check the thermostat for the correct part number and for correct operation. Refer to
Procedure 008-013 in Section 8
.

Water pump is malfunctioning

Check the water pump for correct operation. Replace the water pump if necessary.

Radiator swing check valve is malfunctioning (if equipped)

Check the swing check valve for correct operation. Refer to the OEM service manual.

Air or combustion gases are entering the cooling system

Check for air or combustion gases in the cooling system. Refer to
Procedure 008-019 in Section 8
.

Torque converter cooler disc is not installed correctly

Check the disc for correct installation. Refer to
Procedure 008-062 in Section 8
.