Patent attributes
A water jacket of a cylinder block includes a main passage and a sub-passage. The main passage is formed along the periphery of a cylinder bank, and extends between a plurality of head bolt bosses and the cylinder bank. The sub-passage is formed at a position spaced from the cylinder bank farther than the main passage, to diverge from the main passage at a first position, and join the main passage at a second position downstream of the first position. A first head bolt boss by which coolant flowing from a coolant inlet initially passes is interposed between the main passage and the sub-passage. The first position is located between the first head bolt boss and the coolant inlet. The second position is located between a second head bolt boss by which the coolant passes next, and the first head bolt boss.
