Patent ID: 7930999

Claim:
A cooling water passage structure for internal combustion engines having a cylinder block and cylinder bores, comprising: a water jacket for flowing of cooling water provided on the peripheries of said cylinder bores; a lateral suction passage integrally formed with a side wall of said cylinder block having bolt holes formed for fastening a cylinder head to said block; said lateral suction passage passing through said cylinder bores at a height in the vicinity of the water jacket bottom; said lateral suction passage being arranged on the outside of and perpendicular to said bolt holes; wherein a suction vertical passage rising from the cylinder block up to the cylinder head is formed integrally with the rear end side of said suction lateral passage and the top face opening on the cylinder block side of the suction vertical passage and the bottom face opening in the cylinder head side are sealed with a cylinder head gasket at the same time; and wherein an opening communicating with said suction vertical passage and an outlet opening for cooling water which cools the cylinder bores is formed in the rear surface of the cylinder head while a water passage containing a path for connecting said two openings and having an outlet and an inlet to a heater and an outlet to a radiator is provided in order to cover the rear surface of the cylinder head.