Abstract: A coolant system and method for control of cylinder temperature in a multiple cylinder internal combustion engine includes an inlet rail for receiving coolant from a pump, an outlet rail located on a side of the cylinder head opposite the inlet rail and a plurality of individual coolant flow passages extending within the cylinder head and connecting the inlet rail with the outlet rail. A control valve and an associated temperature sensor are provided within each of the coolant flow passages and a controller individually controls each of the control valves in accordance with a signal received from its associated temperature sensor. The control valves may be controlled to bring the temperatures detected by their associated temperature sensors into conformance with an optimum temperature predetermined for engine speed and/or engine torque load.