Imagine you are driving at highway speed jamming to your favorite song when suddenly, you feel this weird resistance from the steering wheel. You find yourself having to exert more effort in directing your vehicle and you start to ask yourself: “Why is my steering wheel hard to turn?”
If you ever find yourself having difficulties maneuvering or turning the steering wheel, chances are, your power steering has failed.
What Happens When Power Steering Goes Out?
There are many potential causes for a loss of power steering. Furthermore, what potentially could go wrong depends on whether your car has hydraulic, electric or hydro-electric power steering.
Sometimes the power steering works just fine but may become noisy, either because of loose or slipping belts, bad bearings, or air in the hydraulic system – this air problem can happen without warning even if the power steering fluid isn’t low and hasn’t been drained. The noise can be annoying and a slipping belt or foamy fluid may make the steering feel strange.
Types Of Power Steering Systems
Depending on what car you drive, the power steering could be any of the three types:
- Hydraulic Power Steering
- Electric Power Hydraulic Steering
- Fully Electric Power Steering
Hydraulic systems use hydraulic pressure from a power steering pump. This pump, which is driven by the engine drive belt, delivers pressurized power steering fluid to the steering gear.
Electric power steering systems use a motor instead of a hydraulic pump. In a fully electric power steering system, the electronic control unit takes control of the steering dynamics.
Electric hydraulic systems use electrically-driven hydraulic pumps instead of the engine-driven ones on conventional hydraulic systems.
|Power Steering System||Problem|
|Hydraulic Power Steering||Lack of fluid supply due to power steering fluid leak
Failing hydraulic pump
Failed steering gear
Variable Power Assist Issues
Clogged fluid reservoir screen (starving the pump and making it noisy)
|Electric Power Hydraulic Steering||Damaged wiring
Failing electric motor
Power steering fluid leak
Failed steering gear
|Fully Electric Power Steering||Worn-out electrical wiring
Overheated EPS motor due to aggressive prolonged steering maneuvers
Failing electronic parts
If there’s a loss of fluid pressure in a hydraulic power steering system, your car will either have limited steering assist or lose steering assist altogether. When that happens, your car’s steering system will revert to manual operation (i.e., your muscles do all the work). As a result, the steering wheel will become very difficult to turn.
Electric power steering can stop working suddenly and render the vehicle very difficult to drive as well.
You may also experience a loss of power assist when there’s a problem in an electric or hydro-electric power steering system.
In short, the handling of your 2000s car would be just as heavy as a 1960s vehicle—difficult and tiring to operate especially at low speeds.
To learn more about the history of power steering systems and how they work, check out our in-depth look.
Power Steering Failure Causes
Here are the common culprits of a failing hydraulic or electric power steering system:
Loss of power steering fluid
A drop in your power steering fluid level indicates a leak somewhere in the system. Check the hoses, seals, and the hydraulic pump for any signs of leaks to avoid draining the fluid.
Damaged hydraulic pump
Loss of power steering fluid can damage the hydraulic pump and cause problems in your steering. So, what happens when the power steering pump goes out?
If the damage is very recent, you may begin noticing some noises. This can happen as performance deteriorates from smooth to hard-to-steer operation. When the pump fails altogether, you’ll have zero steering assist.
A power steering pump that’s leaking will cause the fluid to deplete faster, resulting in noise and, eventually, a loss of steering assist.
Snapped or slipping serpentine belt
An engine-driven hydraulic pump spins because a belt driven by the crankshaft pulley. When snapped or slipping, the belt will leave the pump powerless and, therefore, won’t be able to supply the system with hydraulic fluid.
Worn electronic components
As was mentioned earlier, electric power steering systems have a steering torque sensor, an electric motor, and a dedicated module, which is supplied with power through fuses and wiring. Should any of these components or the wiring fail, a partial or complete loss of steering assist will occur.
What to Do When the Power Steering Goes Out
You can easily tell when the power steering begins to fail as the steering wheel will become very difficult to turn. In some cases, power steering failure happens gradually, while, in other instances, the failure happens spontaneously. In fact, it can happen while driving and catch drivers by surprise.
Most of the safety tips outlined below are pretty obvious, but not all drivers know the best way to react in such a situation.
Here’s a checklist of the things you need to do when the power steering system fails while you’re on the road:
Signal other drivers using your lights
Turn your hazard lights on to let other drivers know that there’s something wrong with your vehicle. By doing this, you’re also allowing them to pass you or practice caution when tailing your vehicle.
Carefully direct your vehicle to the shoulder of the road
Observe the road for approaching vehicles and carefully turn your steering wheel to direct your car towards the shoulder. This would require you to apply extra force, depending on the damage in your power steering system.
Take your time to switch lanes and don’t rush. Keep in mind that you may not be able to counter-steer instantly in bad situations.
Slow down until you reach a full stop
As you pull over to the side of the road, lightly step on the brake pedals. Make sure that there aren’t any fast-approaching vehicles before reducing your speed.
Once you’re on the shoulder lane, apply the brakes gradually until you’ve come to a full stop.
Assess the severity of the issue
Once you’ve parked your vehicle in a safe spot, assess the severity of the problem by turning the wheel left and right—check how hard it is to turn. Here is where you assess whether you can still drive the car to the mechanic or have it towed.
If the weight of the steering wheel is still manageable, you may be able to drive the car to the nearest mechanic. Make sure to drive slow and stay on the outside lanes to minimize steering inputs.
Be hyper aware of your surroundings and observe defensive driving at all times.
Call for a tow truck if in doubt
If you feel that you are unable to steer the vehicle accurately, call for a tow truck. Make sure that your vehicle is safely positioned on the shoulder lane as it might take a while before the tow truck arrives.
An In-Depth Look at Power Steering Systems
Power steering appeared in 1951 on the Chrysler Imperial and it didn’t take long before other automakers followed with their own power steering systems. Hydraulic power steering systems are very common; the steering gear receives up to 1,500 pounds of pressure from a belt driven pump that has a large pulley. Small pulleys (like the alternator) are for speed and large pulleys (like the power steering pump and A/C compressor) provide less speed but more torque, which is necessary for any pumping operation.
The steering gear is designed to divert the pressure in such a way that it provides power assist whenever the steering wheel is turned, usually by way of a spool valve connected to the base of the steering column.
Systems with a Steering Box and Pitman Arm
Older steering systems use a steering “box” with a Pitman arm connected to a drag link, which in turn is connected to tie rods that transfers turning force to the wheel spindles. The wheel spindles swivel on one or two ball joints, depending on the design of the suspension system.
The steering box has, in addition to its mechanical connections, two hydraulic lines, both connected to the pump. One line carries high pressure hydraulic fluid to the steering gear and the other line is the power steering return line, which carries fluid from the steering gear (through a long pipe with or without cooling fins) back to the power steering reservoir, which typically has a screen to prevent solid contaminants from making their way to the pump itself. Remember that screen in the bottom of the reservoir – it’s important.
Some fluid reservoirs are mounted right on the hydraulic pump, but more often on later models they are mounted remotely, with large oil-proof feed hoses feeding fluid to the pump.
Hydraulic Rack and Pinion Steering Systems
Hydraulic rack and pinion steering is a simpler, lighter design with fewer steering parts – there is a pinion gear meshed to a rack positioned between the left and right tie rods that transfer the rack movement to the wheel spindles.
The pinion gear is connected to the steering column, and there is a valve between the pinion and the column that directs fluid to one side of the rack piston or the other, depending on which way the steering wheel is turned. This system has high pressure feed and return lines much like the steering box version and is less likely to develop steering play over time.
Some later model cars have removed the belt driven pump and replaced it with a pump driven by an electric motor to take some of the load off the engine, but the pump and fluid lines work the same way. Since the pump isn’t belt driven, it can be mounted just about anywhere in the engine compartment.
Electric Power Steering (EPS) Systems
Finally, Electric Power Steering (EPS) systems are becoming more prevalent with each passing year. Electric power steering typically has a steering torque sensor, an electric assist motor, and a dedicated electronic control module. These parts are common to all electric power steering systems. Some EPS systems (not all) use additional input from the steering angle sensor which pre-dates EPS. But the primary purpose of the steering angle sensor is vehicle dynamics (ABS, Suspension, etc.) rather than EPS. Earlier EPS systems have the module, the motor, and the steering torque sensor all built into a module just underneath the dash.
Electric Power Steering Assist motors are almost always three-phase DC motors, which work better in this application than brushed DC motors because they can provide a lot of torque regardless of their driven speed. The motor will have a worm gear meshed to a ring gear, and when the motor spins its worm gear, steering assist is provided by driving the ring gear, which is part of the steering column. The steering rack is mounted the same way, but has no hydraulic lines connected.
It’s important to note that many power systems may have Variable Assist Power steering systems that provide more steering assist during parking lot maneuvers than at road speed. Regardless of the type of power steering used (EPS or Hydraulic) not every system has this feature. Steering effort can be affected on hydraulic systems if the Variable Assist is malfunctioning.
Later EPS systems have the three primary components (motor, module, torque sensor) mounted on the steering rack. In most cases, regardless of where the EPS unit is placed (under dash or in the rack) the entire EPS assembly will need to be replaced if there are problems with the steering system, and most makes require programming and learning elements of the job that make it difficult for a DIY person.
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Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.