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Mechanical seals have been applied as sealing devices for water pumps of automotive engines. The mechanical seal plays an important state. Therefore, there are many kinds of constructions. This paper is concerned with the FEM (Finite Element Method) analytical results for various water pump seal construction. It becomes clear that the property of heat transfer is closely related to the sealing durability.

In order to improve the reliability of seals for automotive application in practical use, it is considered that further basic investigations concerning sealing characteristics of seals are necessary. However, it has been found, from analyzing seals decided in the market as defective parts, that the troubles of seals in the market are mainly caused by both wrong handling for seals and the use under wrong operating condition which has not been expected by manufacturers of seals. Therefore, in order to improve the reliability of seals, it is important to investigate in detail troubles on functional characteristics of seals and their countermeasures. In this paper, on oil seals, O-rings, water pump seals and dust cover seals as seals for automotive application, the results of investigations are discussed.

End-face type seals have been applied as sealing devices for the water pumps in the cooling systems of automotive engines. However, many troublesome problems have occurred for many years and the countermeasures have been investigated as many times. For examples, the problem of excessive abrasion of seal faces caused by foreign particles in liquid to be sealed was solved by using the sliding materials which had a hither thermal conductivity and a lower coefficient of thermal expansion. Furthermore, the noise problem of the ringing phenomena caused by the stick-slip between sliding surfaces was prevented by changing the carbon material whose lubrication characteristics had a negative slope as weak as possible in the Torque-Speed curve. As a result of these investigations, end face seals of this type have obtained the satisfactory sealing performance for many users' requirements in the present Japanese market.

The mechanical seal in automotive water pumps is critical to the performance and reliability of the engine, requiring consistent, effective sealing performance and long operating life. In recent years, the advent of maintenance free performance requirements and increasingly severe operating conditions have resulted in significant changes to the variety and concentration of additives in cooling systems. As a consequence of these changes to the additives, various types of premature seal leakage failures have occurred during service operation. These have been categorized into four types of failure modes and compared with seals providing normal service in order to establish simulated test conditions for engine coolants containing various additives. This paper reports on the various types of failure mechanisms that were found to occur during simulated performance testing and the corrective measures that will eliminate their occurrence