ISM, ISMe, and QSM11 – Coolant Loss – External

Symptom Tree  t020

This is symptom tree t020
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 from hoses, drain cocks, water manifold, jumper tubes, expansion and pipe plugs, fittings, EGR cooler vent lines, turbocharger coolant supply and return lines, turbocharger actuator coolant supply and return lines, EGR cooler coolant supply and return lines, EGR cooler, EGR valve, radiator core, air compressor and cylinder head gaskets, lubricating oil cooler, water pump seal, and OEM-mounted components that have coolant flow. If necessary, pressure-test the cooling system and perform a turbocharger leak test. Refer to Procedures 008-018, 008-045, and 010-033.


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

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


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.


Air or combustion gases are entering the cooling system

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


Engine is overheating

Refer to the Coolant Temperature Above Normal symptom tree.

Last Modified:  20-Jul-2006