Improving Engine Coolant System Performance With the Science of Sealing Technology 2003-01-0616

Automotive engines require highly reliable cooling systems for optimum performance. System reliability is dependant on individual components performing their prescribed service without failure for a given time when operated correctly in a specific environment. The water pump seal is the most critical component within the cooling system. The seal faces are in sliding contact and subjected to changing conditions for temperature, pressure and speed that are dependant on the owner's driving profile. More importantly, the engine coolant fluid can have a major impact on the performance of the water pump seal. Engine coolants with additive packages are not designed to aid the lubrication processes occurring at the seal faces. These types of fluids are designed to maximize heat transfer and prevent boiling or freezing during any possible normal operating conditions. In addition, the function of the engine coolant is to protect metal parts from corrosion. Some coolants have additives that are designed to plug small leaks in the system. Engine coolant pump failure analysis studies identified a failure mode referred to as filming. This must be taken into account in the design of the seal and the materials of construction.

Analysis tools have been developed to aid in the evaluation of the water pump seal for the wide range of operating conditions required. This has allowed for the analysis of a new family of materials. Extensive testing has confirmed that the new materials have exceptional wear resistance. The major causes of failure due to seal face wear have been eliminated where new materials have been applied.

Results of the test work are presented. This work has identified high performance materials, expected to help extend the service life of water pump applications beyond current system life for both normal and extreme service conditions. This substantial improvement in overall system reliability has been achieved through the application of fundamental Tribological principles and techniques, a branch of the Science of Sealing Technology.