M11 Series – Service Manual – 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, draincocks, water manifold, jumper tubes, expansion and pipe plugs, fittings, radiator core, air compressor and cylinder head gaskets, lubricating oil cooler, water pump seal, cylinder block, and OEM-mounted components that have coolant flow. If necessary, pressure-test the cooling system. Refer to Procedure 008-018.


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.


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 and the OEM service manual.


Cooling system hose is collapsed, restricted, or leaking

Inspect the radiator hoses. Refer to Procedure 008-045.


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:  08-Jan-2004