Hydro-boost brakes work by applying hydraulic pressure from the power steering system to assist in braking. When the brakes are applied, hydraulic fluid flows from the power steering pump to increase braking effort, while fluid also flows from the hydro-boost system to the steering gear to assist in power steering.
The hydro-boost system was first developed by Bendix in 1973 as an alternative to the vacuum booster brake systems being used on many diesel trucks. This improved braking system took up much less space and was more effective, allowing vehicles to fall in line with new federal regulations requiring decreased stopping distance with less brake pedal effort.
Hydro-boost brakes quickly grew in popularity and started coming standard on many gasoline powered vehicles as well. Since the mid 1990's, hydro-boost brakes have been used on a variety of three-quarter and one ton GM, Chevy, Dodge and Ford trucks, especially those with a diesel engine. Hydro-boost brakes are also used on powerful sports cars, such as the V8 Ford Mustang, which has featured them every year from 1996 to 2014.
Hydro-boost brakes can experience a variety of different problems that may affect their operation, many of which results in noises coming from the brake system. If problems occur, the vehicle should be taken to a mechanic for diagnostic testing.