N14 Base Engine Troubleshooting and Repair Manual – Coolant Loss – Internal

Symptom Tree  t021

This is symptom tree t021
Cause Correction

Lubricating oil cooler is leaking

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


Lubricating oil cooler transfer housing or lubricating oil cooler support is cracked or porous

Check the oil cooler transfer housing and the support. Refer to Procedures 007-047 and 007-003.


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

Inspect the air compressor cylinder head and gasket. Refer to Procedure 012-003.


Aftercooler is leaking (aftercooled engines only)

Check the aftercooler and connections for leaks.


Rocker lever housing is cracked or porous

Inspect the rocker lever housing. Refer to Procedure 003-013.


Air or combustion gases are entering the cooling system

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


Cylinder head is cracked or porous

Remove intake and exhaust manifolds. Check for evidence of coolant leak. If necessary, operate engine at low idle. Pressure-test the cylinder head. Refer to Procedure 002-004.


Cylinder head gasket is leaking

Check the cylinder head gasket. Refer to 002-004.


Cylinder liner is corroded or cracked

Check the cylinder liners for corrosion or cracks. Refer to Procedure 001-027.


Fuel heater is malfunctioning (if equipped)

Check the fuel heater and replace, if necessary. Refer to the OEM service manual.

Last Modified:  05-Jan-2004