Is there an unusual noise from the steering wheel and is it particularly heavy? Is the power steering broken?

When we are driving, we always encounter various problems, among which unusual noises when steering are one of the most frequently asked questions on forums.

But I believe that when we talk about cars and car repairs, the steering system is a system we often overlook. Today, let's talk about an important component in the steering system: the power steering.

Before talking about the power steering pump, we need to have a basic understanding of this thing. In fact, many people know about the power steering pump and also know that it is used for assistance.

To put it plainly, the steering system in a car, whether it's a rack-and-pinion type or another form, will feel very 'heavy' if you turn the steering wheel directly. The power steering pump is a component that helps us make steering easier.

If we were to categorize them, the power steering systems equipped in our cars can roughly be divided into three types according to Baidu Encyclopedia: 'mechanical hydraulic power steering system, electronic hydraulic power steering system, and electric power steering system.'

These three types of power steering systems, however, are each different. Let's talk about this below.

Mechanical hydraulic power assist is the most common operating method for power steering pumps. It has existed since 1902 and can be said to be a 'century-old shop' in the power steering industry.

The main components of this device are basically the hydraulic pump, oil pipes, pressure and flow control valve body, V-shaped drive belt, and oil reservoir, etc.

To briefly explain the working principle, its core principle is to take a portion of the engine's power, convert it into hydraulic oil pressure through the power assist pump, and then use the pressure to drive the hydraulic cylinder to generate force, helping us steer.

The advantage of this type of power steering is that it is particularly mature and low-cost. But its drawback is also obvious: for vehicles equipped with this power steering, the power steering pump is always working, whether you are steering or not.

Especially in the subdivisions of hydraulic power steering systems: the constant-pressure hydraulic power steering system ensures that the pipelines are always under high oil pressure at all times.

Although maintaining high pressure is not a problem, don’t forget one thing: increasing the oil pressure requires consuming engine power. If you’re working without steering, the engine power is wasted, and the car’s fuel consumption naturally increases. 

Moreover, during the startup and uphill stages when the engine power is already tight, using this main method may cause a lack of power, making the steering wheel feel heavier and affecting our user experience.
 

Actually, the structure of the electronic hydraulic power assist system is quite similar to that of the mechanical hydraulic power assist, and the principle is also pretty much the same. The only difference is that its power source is no longer provided directly by the engine, but by an electric motor.

How should we understand this? Earlier, we mentioned that the mechanical hydraulic assist isn’t working all the time, right? Doesn’t it consume engine power and increase fuel consumption?

Then let's change the approach. Instead of using the engine to power the pump to pressurize the power steering fluid, we directly switch to an electric power steering pump, using the car's electricity to pressurize the fluid, thus starting to work.
 

What are the benefits of this? Unlike mechanical structures, motors can be controlled by an electronic control system to turn on or off, and even the amount of force they provide can be controlled.

In this way, a car equipped with an electronic hydraulic power assist system not only allows the power pump to shut off when not in use, saving fuel, but this system can also adjust the level of assistance based on the vehicle's speed and usage.

For example, when maneuvering at low speeds, the electric power assist pump can operate at full power, making the steering wheel lighter. At high speeds, the power assist pump can operate at a lower level, making the steering heavier and the car more stable.

Because it performs better and is more energy-efficient, more and more cars are now using this type of steering assist. However, there are even more efficient options when comparing efficiency.

Besides the ones we mentioned earlier, there is another type of electric power steering system. The EPS we see on some vehicles (mainly mini trucks) is this kind of assist. 

Its principle is even simpler. We can understand it like this: it’s just putting a motor on the steering mechanism to help us apply force. However, if we distinguish in practice, its installation position can vary.

Since this system no longer has a hydraulic system, it eliminates the energy conversion from motor to hydraulic pressure and from hydraulic pressure to power assist. With fewer conversions, the efficiency naturally increases. Therefore, in theory, it is less likely to break down and is more efficient.

Of course, just like the whole vehicle, no matter how good a power steering system is, it won't work properly without maintenance and care. So, what should be paid attention to when using these types of power steering systems?

Simply put, mechanical hydraulic power steering relies on power steering fluid inside the system to function, so during regular use, it is important to ensure that the fluid in the reservoir is never low. Additionally, since the internal fluid is under high pressure, we should also avoid turning the steering wheel to the end for extended periods.

As for electronic hydraulic power steering, the points to note are basically similar to those for mechanical hydraulic power steering.

Regarding the EPS electronic power steering system, because its structure is very simple but highly electronic, normally we only need to pay attention to whether there are any fault codes or abnormal sensations.

Of course, besides the issues mentioned above, if one day you suddenly find that your steering wheel has become heavy or there is an unusual noise when turning, be sure to check the steering system immediately.

Since we are talking about malfunctions, let's briefly discuss the common causes of hydraulic power steering system failures, so that when we encounter problems in the future, we can prioritize checking these issues:

1. Insufficient hydraulic oil

The most obvious feedback of insufficient hydraulic oil is difficult steering and a heavy steering wheel. In addition to this, a lack of oil may cause components to not be properly lubricated and cooled, which can lead to abnormal noises and unusual wear.
 

2. Hydraulic oil deterioration or impurities

Apart from insufficient hydraulic oil, if hydraulic oil is used for too long, it may deteriorate, causing increased viscosity and poor flow, which can lead to abnormal pressure rise and make the steering wheel heavier. In severe cases, the power steering pump may also be damaged.

Impurities, and even air, can also cause problems in the power steering system. Simply put, impurities in the oil may block the pipelines or enter components, causing abnormal wear on the power steering pump. Air, on the other hand, can lead to unstable power transmission, making the steering force sometimes strong and sometimes weak, or inconsistent.

For such issues, first check the power steering fluid filter. If it is clean, promptly replace the power steering fluid, which may solve the problem.

3. Power Steering Pump Damage

If your car's steering suddenly becomes very heavy or makes unusual noises when turning, and the above issues have all been ruled out, you should consider whether the power steering pump itself is malfunctioning. At this point, professional maintenance personnel are needed for testing.

● Editor's Note:

In fact, the power steering system has evolved over time and has given rise to many advanced technologies, such as variable steering ratios and collapsible steering columns. I remember the first time I encountered electronic power steering was during the era when the 'Santana 2000' was first launched. At that time, on a certain model of car, after turning the steering wheel, it always felt like the steering was a beat slow, and there would also be a motor sound coming from beneath the steering wheel. But today, electronic power steering in cars can already be fast, precise, and even provide road feedback. The progress has indeed been rapid.