Do not ignore low power steering fluid. If the reservoir is low, fluid is leaking somewhere -- power steering is a sealed system that does not consume fluid. Driving with low fluid accelerates pump wear and can lead to sudden loss of power assist, making the steering wheel extremely hard to turn. This is dangerous, especially at low speeds and in parking situations. Check for leaks and repair them before they leave you struggling to steer.
How Power Steering Works
In a traditional hydraulic power steering system, a pump driven by a belt on the engine pressurizes power steering fluid to about 1,200 to 1,500 PSI. This pressurized fluid flows through hoses to the steering rack or gearbox, where it pushes a piston that assists your steering effort. When you turn the wheel, a valve directs the fluid to the correct side of the piston, making the turn feel easy.
The pump is the component you hear most often. It is a rotary vane pump that spins at engine speed and is constantly pressurizing fluid. When something goes wrong with the pump, the fluid level, or the system's integrity, you hear it.
Check the Fluid First
Pop the hood and locate the power steering fluid reservoir. It is usually a small, translucent plastic reservoir with a cap labeled "Power Steering" or marked with a steering wheel icon. On some vehicles, it is built into the pump itself and has a dipstick on the cap.
Check the fluid level against the markings on the reservoir or dipstick. There are usually "Hot" and "Cold" markings. If you have been driving, use the "Hot" line. If the car has been sitting, use the "Cold" line.
If the fluid is below the minimum line, top it off with the correct type of power steering fluid for your vehicle (check the owner's manual -- not all power steering fluid is the same). Then inspect for leaks.
Common leak locations:
- The pump shaft seal (where the pulley attaches to the pump) -- look for wetness around the front of the pump
- High-pressure and return hoses -- trace the hoses from the pump to the steering rack and check for wet spots, especially at connection points
- The steering rack boots -- the rubber boots at each end of the steering rack. If these are swollen or wet, fluid is leaking from the rack seals
- The reservoir itself -- cracks or deteriorated grommets
A small leak can be difficult to spot. Place a piece of cardboard under the front of the car overnight and check for red or amber fluid stains in the morning.
The Whining Pump
If the fluid level is correct and there are no leaks, the pump may be wearing out internally. The vanes inside the pump can wear, the bearings can roughen, and the internal seals can degrade. The result is a whining or groaning noise, especially when the wheel is turned to full lock (all the way left or right).
A mild whine that has been present since the car was new is normal for some vehicles -- power steering pumps are not silent. What you are listening for is a change: a new whine that was not there before, a whine that is getting louder over time, or a groaning sound under load.
A pump that whines under full lock but is quiet during normal driving is wearing but not yet critical. A pump that whines constantly, even when driving straight, is further along. And a pump that groans loudly and makes the steering feel notchy or sticky is close to failure.
Pump replacement typically costs $200 to $500 for parts and labor, depending on the vehicle. The pump itself is $80 to $250, and labor is 1 to 2 hours.
Air in the System
If you recently had the power steering fluid topped off, a hose replaced, or any work done on the system, air may be trapped in the fluid. Air in the system causes the pump to cavitate -- the pump tries to pressurize air bubbles along with the fluid, creating a buzzing, whining, or moaning sound.
To bleed air from the system: with the engine running, slowly turn the steering wheel from full left lock to full right lock several times. This forces fluid through the entire system and pushes air bubbles back to the reservoir where they can escape. Check the fluid level after bleeding, as it may drop.
If the fluid in the reservoir is foamy or bubbly, air is definitely present. Keep cycling the wheel until the bubbles are gone and the fluid looks clear.
Electric Power Steering
If your car was made after 2012 or so, it may use electric power steering (EPS) instead of hydraulic. EPS uses an electric motor mounted on the steering column or rack to provide assist. There is no fluid, no pump, and no belt.
EPS systems are generally quiet, so a whining noise from an EPS car is less common and can indicate:
- A failing electric motor in the steering assist unit
- A problem with the steering rack itself (worn gears, dry spots)
- A bearing in the steering column
EPS faults usually trigger a warning light on the dashboard (a steering wheel icon, sometimes with an exclamation mark). If you see this light along with the noise, the EPS control module has detected a fault and may reduce or disable power assist. This needs professional diagnosis.
When to Act
Do not drive with a power steering system that is groaning and the wheel feels heavy. Loss of power assist at low speed, while parallel parking, or in an emergency maneuver can be dangerous. If the noise is mild and the steering feels normal, you have time to schedule a repair. If the noise is loud and the steering is stiff, get it checked immediately.
If your car also pulls to one side, the steering issue and the pull may be related -- a failing rack can cause both symptoms.
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Written by Sarah Mitchell
Sarah writes about home improvement and practical DIY topics. She focuses on clear, step-by-step guides that anyone can follow.