Cummins N14 STC, Celect, Celect Plus – Service Manual Coolant Loss – External

Symptom Tree  t020

This is symptom tree
Cause Correction

Coolant level is above specification

Check the coolant level. Refer to the OEM service manual.


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.


Aftercooler is leaking (aftercooled engines only)

Check the aftercooler and connections for leaks.


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.


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 the OEM service manual.


Coolant fill line is restricted or obstructed

Check the coolant fill line for restrictions or obstructions. 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.


Engine is overheating

Refer to the Coolant Temperature Above Normal troubleshooting symptom tree in Section TS.

Last Modified:  20-Mar-2012