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

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 the Coolant Loss Pre-Troubleshooting Overview in Section TS.

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.

Misdiagnosed coolant leak (external)

Pressure test the cooling system. Inspect 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 OEM-mounted components. NOTE: If the truck is equipped with an Auxiliary Power Unit, make sure the unit is not leaking. Refer to Procedure 008-018 in Section 8 or the OEM service manual.

Fuel heater is leaking coolant

If applicable, check the fuel heater for coolant leaks. Refer to the OEM service manual.

Transmission oil cooler or torque converter cooler is leaking

If applicable, check the transmission oil cooler and torque converter cooler for coolant leaks. Refer to the OEM service manual.

Aftertreatment diesel exhaust fluid tank heater is leaking coolant

Inspect the aftertreatment diesel exhaust fluid tank for internal coolant leaks. Refer to the OEM service manual. Check the concentration of the diesel exhaust fluid. Refer to Procedure 011-056 in Section 11.

EGR mass measurement flow assembly is leaking coolant

Pressurize the cooling system. Refer to Procedure 008-018 in Section 8. Inspect the EGR mass measurement flow assembly for internal coolant leaks. Refer to Procedure 011-066 in Section 11.

Air compressor cylinder head is cracked or porous, or has a leaking gasket

Inspect the air compressor air inlet and outlet tubes for signs of coolant. Refer to
Procedure 012-007 in Section 12.

EGR cooler leaking coolant

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

Aftertreatment fuel injector is leaking coolant

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

Turbocharger bearing housing leaking coolant

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

Cylinder head injector sleeve(s) are leaking coolant to the fuel return, or fuel to the cooling system

Check for fuel in the cooling system or coolant in the fuel tank(s). Refer to the OEM service manual. If coolant is found in the fuel tank(s), or fuel is found in the cooling system, pressure test the cylinder head. Refer to Procedure 002-004 in Section 2.

Cylinder liner is corroded or cracked, or the cylinder block is cracked or porous

Remove the oil pan. Pressure test the cooling system to check for leaks. Refer to Procedure 001-027 in Section 1.

Lubricating oil cooler is leaking

Check the lubricating oil cooler for coolant leaks. Refer to Procedure 007-003 in Section 7.

Cylinder head gasket is leaking

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

Cylinder head is cracked or porous

Pressure test the cylinder head. Refer to Procedure 002-004 in Section 2.

Cylinder block is cracked or porous

Inspect the cylinder block. Refer to Procedure 001-026 in Section 2.