Today, power steering is standard on pretty much all production vehicles. Most power steering systems today use a rotary-vane pump connected to the car’s engine by a belt to pressurize a hydraulic fluid. That hydraulic fluid transfers some of the engine’s energy to the steering mechanism, to lessen the effort required by the driver to turn the steered wheels when driving.
Your power steering fluid is that hydraulic fluid. In addition to it’s job as a hydraulic fluid, it also serves as a lubricant. Just like your car’s engine relies on engine oil to keep it in working order, your power steering system components rely on power steering fluid to keep them lubricated.
How Power Steering Works
We mentioned earlier that most power steering systems use a pump connected to the engine to pressurize power steering fluid. The fluid is pumped to a rack and pinion unit. As the steering wheel is turned, a piston moves in the desired direction to apply extra force to the fluid. That extra force helps move your car’s tie rods (a steering component that essentially connects the rack and pinion to the steering knuckle) and turn the wheels in that direction.
If the power steering system ever fails, you’ll find that you’re still able to turn the car. It does, however, require considerably more effort.
In recent years, electronic power steering systems have begun to see use on production cars. This replaces the engine driven pump with an electronic actuator. The actuator draws it’s power from the vehicle’s electrical system, rather than the engine. The basic concept remains the same, though.
What Your P/S Fluid Does
Most people know that they need to keep their engine oil filled to the correct level. They also know that they need to replace it with new oil periodically.
The same is true for your power steering fluid. Your power steering system generates a lot of heat, which causes the power steering fluid to break down over time. Also, because your power steering system is unfiltered, the fluid accumulates contaminants from normal use and wear, plus any dirt and moisture that find it’s way into the reservoir.
Because of this, it’s recommended to perform a power steering flush every 30,000 miles to keep your power steering system working it’s best. Avoiding this service may lead to additional stress and wear on the system, and repairs can be quite costly.