PURPOSE: To eliminate protrusion of a connection pipe by way of directing it to the side of an engine, to miniaturize a V type engine and to prevent interference of parts by arranging the connection pipe of water outlet cap on the side of the engine rather than the outside surface of the cap.

CONSTITUTION: On a V type engine 2, primary and secondary side both engine banks 4, 6 are arranged in a V shape. Additionally, slippage of the both side engine banks 4, 6 is formed by a step difference 28, while an allowable space S is formed by gaps 30, 32 between the both sides. Furthermore, in the gaps 30, 32 between the both sides, a water outlet cap 34 to introduce each cooling water of the both side engine banks 4, 6 is installed. Additionally, to the water outlet cap 34, a water hose 46 is connected through a connection pipe 44. In this case, the connection pipe 44 is directed to the side of the V type engine 2, that is, arranged in the allowable space S inside rather than the outside surface A of the water outlet cap 34.