ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 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 engine leak

Inspect the engine and its components for seal, gasket, or draincock leaks. Inspect the radiator, heat exchanger, cab heater, hoses, and connections. Pressurize the cooling system if necessary to determine source of leak. Refer to Procedure 008-018.


Cooling system hose are collapsed, restricted, or leaking

Inspect the cooling system hoses for restrictions, obstructions, and leaks. Refer to Procedure 008-045.


Cooling system pressure cap is not correct, is malfunctioning, or has a low-pressure rating

Inspect the pressure cap. Refer to Procedure 008-047 and the OEM service manual.


Engine is overheating

Refer to Coolant Temperature Above Normal, Gradual Overheat or Coolant Temperature Above Normal, Sudden Overheat symptom trees.


Coolant loss through radiator overflow

Check and review OEM plumbing to make sure no high-pressure coolant can cause backflow. Check vent lines and fill line for restriction. Refer to the OEM service manual.


Transmission oil cooler or torque converter cooler is leaking

Check the transmission oil cooler and torque converter cooler for coolant leaks. Refer to the OEM service manual.


Wet exhaust manifold and turbine housing leaking coolant

Pressure-test the coolant system. Refer to Procedure 008-103.

Last Modified:  20-Jun-2005