Cooling system for an engine

A cooling system for an engine wherein a cylinder block side is mounted with a stagnation chamber for stagnating a temperature sensing unit of a sub-thermostat portion of cooling water discharged to a high temperature passage via an outlet of a cooling water passage of the cylinder block side, enabling opening and closing of the sub-thermostat only via the temperature of the cooling water at the cylinder block side. The cooling system includes a main thermostat and a sub-thermostat for individually controlling the flow of cooling water in a cylinder block and a cylinder head. The stagnation chamber, where a cooling water discharged from the cylinder block is stagnated, is installed inside a sub-thermostat housing where a sub-thermostat is mounted. The stagnation chamber is positioned therein with a temperature sensing unit. The stagnation chamber communicates with a cooling water discharge passage of the cylinder head via a confluence passage.