Before automakers introduced power steering in the 1950s, drivers needed to work harder to keep their vehicles straight or make turns. The simple steering mechanisms of more than a half-century ago have since been replaced with more intricate steering systems for maneuvering vehicles with less effort.
Power steering is integral to safe and efficient driving. Keeping your power steering system well maintained by checking fluids regularly and watching for leaks can help ensure that your car functions as smoothly as possible.
Read on to learn how power steering works, how to identify problems, and what you can do to keep your power steering operating correctly.
What is Power Steering?
Power steering is an automotive system that uses a separate motor or engine power to reduce the effort necessary to turn the front wheels. The assistance helps drivers steer the car and makes it easier to maneuver at lower speeds. It is a welcome feature when turning a corner at slow speeds and when parking.
There are three types of power steering in modern vehicles.
- Hybrid electro-hydraulic
All three power steering systems perform the same function but use different methods. Each variety adds more energy to assist in steering a vehicle, allowing the driver to use less muscle to turn the steering wheel.
Hydraulic Power Steering
For more than 50 years, hydraulic assistance was the prevailing type of power steering. The system consists primarily of a hydraulic pump assembly that allows power steering fluid to exert force on the vehicle’s steering assembly and turn the tires.
The belt-driven pump draws power from the rotation of the engine to do its work. One drawback to the system is the amount of wasted energy. The pump runs all the time, even when the car doesn’t need steering assistance while moving on a straight stretch of road.
Power Steering Fluid
Power steering fluid is the hydraulic fluid that transmits the power in a power steering system. The pressurized fluid decreases the amount of effort required to turn the steering wheel. It also keeps the moving parts in the system lubricated and ensures the hoses, pistons, valves, and power steering pump work as intended.
Types of Power Steering Fluid
Refer to your owner’s manual to learn what type of power steering fluid to use in your car.
- Automatic transmission fluid (ATF). The same fluid used for automatic transmissions can be used in some power steering systems.
- Synthetic power steering fluid. Most newer vehicles use synthetic fluid that is created in a lab. These varieties are usually engineered for specific types of cars or steering systems.
- Non-synthetic, mineral power steering fluid. Mineral hydraulic fluid may be used in some instances that accept ATF.
Tip: Choosing an incompatible fluid can cause damage. Be sure to select a replacement steering fluid that is appropriate for your vehicle.
How to Check Power Steering Fluid
If you begin hearing a whining sound coming from under your hood when you make a turn, or it’s becoming harder to turn the steering wheel, your car might be running low on power steering fluid.
Check your car’s power steering fluid in a few simple steps. First, warm the engine to a normal operating temperature. Get the fluid up to temperature by turning the steering wheel in one direction until it stops. Then crank it all the way in the opposite direction. Repeat this back-and-forth process several times. Follow the below steps next.
- Turn off the engine.
- Locate the power steering reservoir under the hood and wipe it, and the cap, clean with a cloth.
- Check the fluid level by viewing the dipstick attached to the cap. Remove, wipe clean and reinsert the dipstick.
- Remove the dipstick again and observe where the level reaches. If it is below the MIN line, add new fluid not exceeding the MAX line.
- Examine the quality of the fluid. Suitable fluid will have a clear appearance and not show any debris. Contaminated fluid will appear dark, cloudy, or foamy.
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When to Change Power Steering Fluid
In general, power steering fluid needs changing every five years or 50,000 miles. Always follow the guidelines in the owner’s manual, which may indicate a different schedule. Changing the fluid or flushing the steering system can help prolong the life of other steering components that cost much more to replace.
In addition to scheduled maintenance, replace the power steering fluid if it appears dark or if any dirt, debris, sludge, or other contaminants are visible. Uncontaminated fluid will have some color and appear clean.
Power Steering Fluid Color
Good power steering fluid is relatively clear and has a red, pink, or amber color. If the fluid is dark brown, black, or foamy, it is contaminated. Replace the fluid or flush the steering system as needed.
Power Steering Fluid Standards
Power steering fluid meets requirements for viscosity, detergents, additives, and other components. Meeting these standards ensures the power steering fluid is safe to use in specific vehicles. Because requirements vary among car makes and models, always use the fluid recommended in your owner’s manual.
Power Steering Pump
At the heart of an automobile’s power steering system is the pump. A power steering pump is a straightforward machine that pushes hydraulic fluid where it’s needed. Your car’s speed dictates the amount of flow coming from the pump.
A rotary valve detects the force controlling the steering wheel’s movement so that the system knows when to assist you. When the steering wheel isn’t turning, both hydraulic lines have equal pressure on the right and the left sides. When the spool valve turns, ports on the appropriate line open to provide higher pressure and assist in turning the wheels.
Signs of a Bad Power Steering Pump
A failing power steering pump may give you clues about its condition:
- Low fluid level in the reservoir
- Puddles or stains in the garage or on the driveway
- Moaning, squealing, or whining noise when you turn the steering wheel
- Increased resistance when turning wheel
- Erratic response to turns
A belt runs from the car’s engine to make the pump operate by turning its pulley. Some vehicles have a serpentine belt that snakes through multiple engine pulleys. Other models have single belts connected to individual pulleys. If any belt becomes glazed, frayed, or breaks, it will cause the system to malfunction.
Problems with Engine Belt
A common problem with power steering is having the pump’s belt slipping. An indication of a slipping belt is the telltale squealing sound when the steering wheel rotates to make a sharp turn.
Power Steering Hoses
For assisted steering to function efficiently, it is crucial that hoses transporting hydraulic fluid in the system be clog-free and have no leaks.
Signs of Bad Hoses
A burst in the hose line will cause the hydraulic fluid to leak, making it harder to turn the steering wheel. Inspect the hoses and other system components regularly. Hoses can deteriorate after years of use or become cracked and dry. Look for cracks and wear. Lightly squeeze the hoses to locate weak areas that will feel soft or spongy.
Electric Power Steering
Electric power steering (EPS) has become the norm for new vehicles. Instead of using a hydraulic pump to send fluid to the steering gear, the gear connects to an electric motor and a control module.
The control module collects data from sensors. It determines how much assistive torque the motor will apply by calculating vehicle speed, turning speed, and the steering wheel’s position. The amount of current used by the motor on the steering gear or steering column affects the assistance from the power steering system.
These electrical systems allow for lighter, quieter, and more effective power steering operation. They have fewer parts than hydraulic systems, require less maintenance, and eliminate dealing with hydraulic fluid. EPS systems draw less power from the engine, which slightly improves fuel economy. Removing a drive pulley and belt from the engine reduces wear and tear.
Another benefit is driver-assist features that use wheel adjustment without driver manipulation are enabled by EPS. Lane-keep assist, lane changes, and automated parking are functions that rely on a car’s electric power steering system.
According to some driving enthusiasts, one disadvantage of EPS is the lack of tactile feedback when steering. They say the system makes it difficult to “feel the road” or sense when tires are slipping because of road conditions. For the average driver in ordinary situations, this type of sensitivity is not an issue.
Electro-hydraulic power steering is a hybrid system. EHPS provides the smooth feel of a conventional hydraulic power steering assist. However, it uses electricity to create pressure instead of drawing power from the vehicle’s engine. This system also improves fuel economy since the electric-powered pump only operates when a steering assist is needed.
These days, the market for electro-hydraulic power steering is primarily heavy commercial vehicles. EHPS can be found on some used cars from several makers.
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