Coolant passage device for internal combustion engine

A coolant passage device that is used in a cooling device for an internal combustion engine forming a coolant circulation flow path between a fluid passage formed in the internal combustion engine and a radiator, and is provided between a coolant outlet portion of the internal combustion engine and a coolant inlet portion of the radiator, the coolant passage device comprising:

• a coolant intake pipe that takes in coolant from the internal combustion engine;
• a delivery pipe to the radiator communicating with the coolant intake pipe;
• and
• at least a delivery pipe to a heater core branched from a central passage connecting the coolant intake pipe with the delivery pipe to the radiator, wherein
• a branch port leading to the delivery pipe to the heater core is opened in an upper portion in the central passage in a state where the coolant passage device is mounted to the internal combustion engine,
• the branch port has a wall surface surrounding the branch port and hanging down into the central passage, and
• the wall surface of the branch port forms an opening facing a direction that is orthogonal to a cross-section of the central passage, the cross-section extending along a longitudinal axis of the central passage at a location of the delivery pipe to the heater core, and towards the internal combustion engine.