Cummins ISX11.9 CM2250 – Service Manual Coolant Loss – External

Excessive internal or external engine coolant loss

Before troubleshooting, it is important to determine the exact complaint by interviewing the driver, looking at the service history, and looking at the ECM information. Refer to Coolant Loss Pre-Troubleshooting Guide located in the Troubleshooting Overview section. NOTE – If the truck is eqipped with an Auxilary Power Unit, make sure the unit is not leaking.

Coolant level is above specification

Check the coolant level. Refer to 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 in Section 8 .

Engine is overheating

Refer to the Coolant Temperature Above Normal – Gradual Overheat and Coolant Temperature Above Normal – Sudden Overheat symptom trees, if applicable.

External coolant leak

Inspect the engine for coolant leaking externally from items such as coolant hoses, drain valves, coolant manifolds, expansion and pipe plugs, fittings, air compressor coolant lines, EGR cooler coolant lines, turbocharger coolant lines, transmission oil cooler or torque converter oil cooler, water pump seal, radiator core, heat exchanger, lubricating oil cooler housing, aftertreatment diesel exhaust fluid tank heater and hoses, aftertreatment diesel exhaust fluid dosing valve coolant lines and OEM mounted components that have coolant flow. If necessary, pressure test the cooling system. Refer to
Procedure 008-018 in Section 8. If necessary, pressure test OEM mounted components. Refer to the OEM service manual.

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 restrictions. Refer to the OEM service manual.

Cooling system hose is collapsed, restricted, or leaking

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

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.

Aftertreatment fuel injector is leaking coolant

Check the aftertreatment fuel injector for coolant leaks. Refer to Procedure 011-061 in Section 11 .

Turbocharger leaking coolant

Check the turbocharger bearing housing. Refer to
Procedure 010-033 in Section 10.

EGR cooler leaking coolant (external)

Check the EGR cooler for leaks. Refer to Procedure 011-019 in Section 11.

Cylinder head gasket is leaking (external)

Check the cylinder head gasket. Refer to Procedure 002-004- in Section 2.

Cylinder block is leaking (external)

Check the cylinder block. Refer to Procedure 001-026 in Section 1.