Abstract: An improved cooling fluid passage configuration provides for uniformity of cooling about the entire periphery of a cylinder liner of an internal combustion engine in addition to improved cooling by increasing the flow in an upper water jacket of a split water jacket design. The cooling fluid passage configuration also provides a reduced pressure drop between a cylinder liner cooling fluid inlet and a cylinder head cooling fluid outlet when compared to conventional designs with a single head feed line, permitting use of a smaller cooling fluid pump and leading to increased efficiency of the engine.