Patent ID: 6978742

Claim:
An engine cooling water passage structure for connecting to a water jacket and a radiator comprising: a cooling water passage unit including; a cooling water supply passage; a water pump for connection to the cooling water supply passage; a thermostat housing in the cooling water supply passage for housing a thermostat, wherein the cooling water passes through the water pump and through the thermostat housing when being supplied from the radiator to the water jacket; a cooling water discharge passage for discharging cooling water from the water jacket into the radiator; and a bypass passage operably couple between the water jacket and the thermostat housing, for returning the cooling water from the water jacket to the thermostat housing and bypassing the radiator; wherein the cooling water passage unit is formed of a plurality of divided sections, said divided sections being previously and integrally formed as a sub-assembly and this sub-assembly being detachably mounted as a unit on an engine main body.