Abstract: A radiator cooling system filter assembly comprising a first housing member, a second housing member and a filter element. The first and second housing members are interconnectable with a snap fitting to form a filter element cavity into which the filter element is disposed during use. The first housing member includes a first cooling hose fitting at one end. The second housing member includes a second cooling hose fitting at one end. The first and second housing members are interconnectable in a manner such that when the first and second housing members are snapped together to form the filter element cavity, the filter element cavity provides a fluid pathway between the first and second cooling hose fitting. In addition, one of the first and second housing members is provided with a valve mechanism selectively operable by a user to provide a fluid pathway between the filter element cavity and the exterior of the cooling system.