This recommended practice is intended as a guide in the usage of mechanical face seals for the engine coolant pump application. the main purpose of the document is to fill the void caused by the lack of a ready source of practical information on the design and use of the engine coolant pump face seal. Included in the document is a compilation of present practices, as in a description of the various types of seals, material combinations, design data, tolerances, drawing format, qualification and inspection information, and quality control data. The terminology used throughout the guide is recommended, and through common usage is hoped to promote uniformity in seal nomenclature.