Abstract: A cooling structure of an engine comprises a cylinder block provided with a wall surface partitioning a water jacket provided to surround a cylinder line and allow cooling water to flow therein and a water-jacket spacer arranged inside the water jacket and provided to regulate flowing of the cooling water. The water-jacket spacer comprises a spacer body having a shape along an outer-peripheral shape of the cylinder line and includes an internal surface facing cylinders, and an expansive member expandable according to an external factor is provided at the internal surface of the spacer body such that the expansive member extends continuously over a range from an one-end side to the other-end side of the cylinder line at a lower part, in a cylinder-axis direction, of the internal surface of the spacer body.

Abstract: A cooling structure of a multi-cylinder engine is provided, which includes cylinder bores formed in a cylinder block, a water jacket surrounding the bores, a cylinder head, and a water jacket spacer accommodated in the water jacket and having a peripheral wall formed corresponding to the cylinder bores. A length of the peripheral wall in cylinder bore axial directions is substantially the same as that of the water jacket. The peripheral wall forms, inside the water jacket, inner and outer channels, and a width of the inner channel is less than that of the outer channel. Communicating holes communicating the inner and outer channels are formed in the peripheral wall at locations between adjacent cylinder bores, respectively. Inter-bore channels into which some cooling fluid flowing from the outer channel into the inner channel flows are provided to parts of the cylinder block between the adjacent cylinder bores, respectively.

Abstract: A cooling structure of a multi-cylinder engine is provided, which includes cylinder bores formed in a cylinder block, a water jacket surrounding the bores, a cylinder head, and a water jacket spacer accommodated in the water jacket and having a peripheral wall formed corresponding to the cylinder bores. A length of the peripheral wall in cylinder bore axial directions is substantially the same as that of the water jacket. The peripheral wall forms, inside the water jacket, inner and outer channels, and a width of the inner channel is less than that of the outer channel. Communicating holes communicating the inner and outer channels are formed in the peripheral wall at locations between adjacent cylinder bores, respectively. Inter-bore channels into which some cooling fluid flowing from the outer channel into the inner channel flows are provided to parts of the cylinder block between the adjacent cylinder bores, respectively.