ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 008-999   Cooling System – Overview

The function of the cooling system is to maintain a specified operating temperature for the engine. Some of the heat generated by the engine is absorbed by the coolant flowing through the passages in the cylinder block and head. Then, heat is removed from the coolant as it flows through the radiator.

Conventionally cooled engines with automatic transmissions typically use oil-to-water transmission torque converter coolers plumbed between the radiator and the engine water pump.

A torque converter cooling system with a remote bypass allows the torque converter to receive coolant flow when the thermostat is closed (engine cold).

The following publications, available through Cummins Distributors or Cummins Dealers, provide cooling system installation recommendations and specifications approved by Cummins Inc.:

• Automotive Installation Recommendations (Cooling System), Bulletin 3382413
• Construction, Mining, Logging and Agriculture Installation Recommendations
  (Cooling System), Bulletin 3382171
• Data Sheets for specific engine models
• Operation of Diesel Engines in Cold Climates, Bulletin 3379009
• Heavy-Duty Coolant/SCA Maintenance Requirements, Bulletin 3387910.

Open the petcocks at the bottom of the radiator and at the bottom of the oil cooler housing. Remove the lower radiator hose. A 20 liter [4 gal]
drain pan will contain the coolant in most applications.

When troubleshooting overheating, remember that too much oil in the oil pan can cause additional heat from friction when the rod journals are submerged in oil. Overfilling with oil raises the oil temperature that is transferred to the cooling system at the oil cooler.

The system is designed to use a specific quantity of coolant. If the coolant level is low, the engine will run hot.

NOTE: The engine or system has a leak if frequent addition of coolant is necessary. find and repair the leak.

During operation, entrapped air mixes with the coolant which results in cavitation corrosion and poor heat transfer. Highly areated coolant can cause localized overheating of the cylinder head and block which can result in a cracked head, scored cylinder liner, or blown head gasket.

Obstructions in the coolant passages will reduce coolant flow, which can lead to overheating.

NOTE: The small holes in the head gasket are especially susceptible to plugging. Their size is critical. Do not enlarge the size of the orifices. Doing so will disturb the coolant flow and will not solve an overheating problem.

Water will cause rust formation, reducing the flow in the smaller coolant passages.

Also, water used as a coolant for even a relatively short period can result in the expansion plugs rusting through, which will allow the coolant to leak.

NOTE: A sudden loss of coolant from a heavily loaded engine can result in severe damage to the pistons and cylinder bore.

Overfueling and Loading

Overfueling can cause the engine to overheat. Make sure that the correct engine electronic control module (ECM) calibration is being used.

Constant overloading (lugging) can cause the engine to run hot.