A single thermostat design was implemented with the introduction of the 2002 ISX engine. The thermostat opens at 82°C [180°F] and is the same thermostat used in previous ISX engines, which were designed with two thermostats.
The ISX 2002 engine with exhaust gas recirculation (EGR) implemented an impeller that is similar to the impeller on the QSX15 engine to maximize the cooling capacity of the water pump. The water pump pulley drive ratio was increased to provide faster water pump speeds to increase cooling capacity. Increased cooling capacity is required because of the flow and heat associated with the EGR.
The functions of the cooling system are to:
Absorb heat from the engine components
Circulate the coolant in the engine and aftertreatment components
Dissipate the heat through the radiator and diesel exhaust fluid supply to prevent freezing
Control coolant temperature by the thermostat.
The coolant must be made up of the correct proportions of water, antifreeze, and supplemental coolant additives (SCA) to perform these functions properly.
Conventionally cooled engines with automatic transmissions typically use a oil-to-water transmission torque converter cooler 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 a Cummins® Authorized Repair Location, provide cooling system installation recommendations and specifications approved by Cummins Inc.:
Data Sheets for specific engine models
Operation of Diesel Engines in Cold Climates, Bulletin 3379009
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