Power steering - the most common problems and their solutions
A steering booster is an integral part of modern cars, as it ensures easy and precise steering, reducing the effort required by the driver when turning the steering wheel. Depending on the design, there are different types of power steering systems, each with its own advantages, disadvantages, and typical malfunctions. In this article, we will look at how a power steering system works, what types of systems there are, how to recognize malfunctions, and what to do to fix them.
How does a power steering system work?
A power steering system is a device that is part of the steering system and helps reduce the physical load on the driver. Its principle of operation is to respond to the rotation of the steering wheel and transmit additional force to the steering rods, either by means of fluid (hydraulics), an electric motor, or a combination of both.
Thus, power steering significantly facilitates maneuvering, especially at low speeds or when parking.
Types of power steering systems
Today, there are three most common types of power steering:
- Hydraulic (HPS)
- Electric (EPS)
- Electrohydraulic (EHPS)
Each of them has its own characteristics, which will be discussed in detail below.
Hydraulic power steering
The oldest type of steering booster. It was first used during World War II on wheeled military vehicles. It began to be used in series production in the 1950s: first on quarry dump trucks and premium passenger cars, after which it was actively introduced as an option, primarily by American automakers.
The hydraulic system uses a pump that forces fluid through valves to create force on the steering mechanism. This is one of the oldest but most reliable technologies. Principle of operation: a pump connected to the internal combustion engine by a drive belt (usually together with other attachments) creates pressure in a separate hydraulic system. While the wheels are in a straight position, this system runs idle. But as soon as the steering wheel is turned in any direction, a special hydraulic ram starts to assist the driver.
Advantages and disadvantages of hydraulic power steering
| Pros | Cons | ||
| Reliability | The system is time-tested and rarely breaks down with proper maintenance | Constant load on the engine | The pump is always running, which affects fuel consumption |
| Simple design | Less electronics, easier to repair | Requires maintenance | Regular fluid replacement, hose and seal inspection |
| Stable operation | Regardless of vehicle speed | Loss of efficiency in case of leakage | May lead to heavy steering |
Electric power steering
Although electric power steering was invented at the dawn of the automotive industry, it was not used in series production until 1993, when the system became truly in demand. After all, it not only eliminates the need for hydraulic pumps and their lubrication, making the steering system more efficient and easier to maintain. Electric power steering reduces energy loss during maneuvering, improves steering accuracy and response speed, and works well with modern driver assistance systems such as parking systems and autopilots.
Electric power steering is essentially the opposite of hydraulic power steering. Firstly, it allows the steering effort to be varied depending on driving conditions, such as speed and engine speed. Secondly, it has no hoses, reservoir or fluid, only sensors, a control unit and an electric motor. The latter, depending on the design of the electric power steering system, can be built into the steering column (mostly in small cars) or into the steering rack (larger cars – SUVs, minivans), or can rotate the steering gear, parallel to the mechanical drive from the steering wheel to the wheels.
Advantages and disadvantages of electric power steering
| Pros | Cons | ||
| Energy efficiency | Works only when needed | Complexity of repair | More electronics — specialized diagnostics required |
| Less load on the engine | No constant drive from the engine | Sensitivity to electrical problems | Power surges or battery problems can affect performance |
| Precise control | Sensors ensure adaptation to speed and driving style | Cost | More expensive to repair and maintain than hydraulics |
Electrohydraulic power steering
Electrohydraulic power steering became widely used shortly after electric power steering, with the first serial application dating back to 1994. This is a hybrid system in which an electric motor drives a hydraulic pump, offering a compromise between hydraulic reliability and electronic adaptability. The use of an electric motor as a drive instead of a belt drive allows the unit to be located anywhere, without being tied to the alignment of the pulleys. The autonomous electric drive allows the power of the amplifier to be regulated and increased when necessary, regardless of the speed of the internal combustion engine. However, it was the “two in one” principle that became the main design problem. Since it was technologically necessary to combine the electronic control unit and the hydraulic pump in a single housing, most EGR failures are due to leaks: fluid gets onto electronic components and contacts, leading to short circuits and corrosion.
Advantages and disadvantages of electro-hydraulic power steering
| Pros | Cons | ||
| Flexibility | Combines the power of hydraulics with the precision of electronics | Complex design | Combining two types complicates maintenance |
| Energy efficiency | The pump only operates when needed | Higher repair costs | More expensive than a purely hydraulic or electric system |
| Improved control | The system adapts to driving conditions | Power supply requirements | Electrical problems can stop the pump |
Power steering system malfunctions and their symptoms
The most common problems in the power steering system include:
- Whistling or humming when turning the steering wheel – worn pump or insufficient fluid level.
- Stiff steering wheel – possible malfunction of the electric motor, pump, or hydraulic fluid leak.
- Knocking in the steering wheel – worn joints or fasteners.
- Error indicator on the dashboard – electronic problem or sensor malfunction.
If these symptoms appear, do not delay – this can lead to a complete loss of power steering.
Which fluid should you choose for your power steering?
The choice of fluid depends on the type of power steering:
- For hydraulic systems, a special hydraulic fluid (ATF or PSF) recommended by the car manufacturer is used.
- For electro-hydraulic systems, a synthetic fluid with increased heat resistance is often used.
- Electrical systems do not require fluid, but require regular diagnostics of the electronics.
Always check the specifications in the car's service book or consult a specialist.
Repair of hydraulic, electric, and electro-hydraulic power steering systems
Steering components, especially the steering rack, are expensive parts, and replacing them can significantly impact a car owner's budget. STS offers several solutions for saving money and effectively troubleshooting:
Diagnostics and restoration are carried out on specialized equipment manufactured by MSG Equipment.
All work and parts used are covered by a warranty of at least six months.
- Diagnostics and repair of the steering system. Thanks to the availability of all necessary spare parts in our warehouse, we perform repair work quickly and efficiently.
- Replacement with new units – steering racks, power steering pumps, steering gearboxes.
- Installation of refurbished units: racks with hydraulic or electric power steering, power steering pumps, reducers, steering columns with electric power steering. Refurbished parts are cheaper than new ones, but are not inferior in quality, as we use only original components from leading global manufacturers.
