The combination comprises a valve controlled piston and cylinder internal combustion engine and a coolant system. The engine has an output shaft and a camshaft driven by the output shaft. The system includes a coolant flow path which passes through the engine in cylinder cooling relation and thereafter through a cooling zone. The system includes a coolant pump comprising a pump housing within the flow path, an impeller rotating structure, a pump impeller, and a damper assembly. The rotating structure is mounted directly to the camshaft so as to be rotatably driven thereby about an axis concentric to a rotational axis of the camshaft. The damper assembly is disposed within the pump housing and is rotatable to dampen torsional vibrations of the camshaft.