Operating Performance of Motor Vehicle Braking Systems as Affected by Fluid Water Content

Automotive hydraulic brake fluids are known to pick up water in service. This paper shows that a major portion of the water picked up by the brake fluid in a braking system is transmitted through the hoses. It discusses two major effects of water pick-up on brake fluid performance-reduction in vapor lock temperature, and increase in low temperature viscosity. Performance data for several “wet” brake fluids operating in actual braking systems at high and low temperatures are presented.