Knocking Noise From the Back of a Car When Parked

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There are numerous strange noises coming from the car’s different parts and gearbox. But every noise has its individuality and they mean differently. But this is a common scenario of hearing knocking noises from the back of a car when parked. After hearing this sound, one may not take an initial step but rapid knocking noise is a concerning matter.

There are several factors responsible for the knocking noise that can be heard while parking a car. The main ones are broken steering rack, soybean link damage, struts bushing turn out, ball joint problems, and low oil level. 

A knocking or clunking noise is seen when these problems are seen intensely. So it is important to fix these. This article will discuss the causes in detail and how to eliminate them. Also, some tips to avoid these in the future will be shared with you. Hopefully, I will read this article from beginning to end to get more understanding. 

Reasons for Knocking Noise From the Back of a Car When Parked

Hering such kinds of noise as knocking or clunking noise when parking your car is not a good sign. Here are some reasons behind this. In this section, you are going to see some exact reasons that help you to understand why this sound occurs.

Steering Rack dismissal

Whether you are driving on a local street or highway, steering makes the difference. It efficiently converts the rotation of the wheel to a swiveling movement. By doing so, the car turns left to right effortlessly without any wear and tear.

However, if there are problems with the steering, such as a broken steering rack, the handling could be compromised. This is why many car owners speak out that it is a common failure for a knocking or clunking noise from the back even if you are parking.

Worn out sway bar or drop link

The sway bar drop link bar and stabilizer bar all are the same. But when this bar link failed to serve in its nature, the clunking noise occurred significantly. Besides, there are some other signs of a faulty worn sway bar, for instance, rattling noises from the wheels, improper handling, and imbalanced steering wheels.

Shocks and strut bushing leaking

Shocks and struts both are extremely demandable and obligatory suspension parts of any vehicle. The rubber bushing is the main part of the shocks and struts. In most cases, the bushing seems to break down or simply disperse from the top.

When this happens, the driver may feel inconsistent movement, clunking, or rattling sounds from the back when driving on rough roads, poor handling, and improper steering. Interestingly, the sway bar or drop link, arms, ball joints, strut mount, and shock absorber will fail to serve when the shock bushing breaks down.

Faulty ball joints

Another reason for harsh clucking sounds is damaged ball joints. It is most possible that you will hear a weird knocking or rattling noise. Ball joints allow the vehicle to move freely in any direction while all the parts are directly attached to the vehicle. By doing so, the driver can easily control the vehicle when cornering or turning.

In the meantime, the wheels rotate and move up and down or side to side efficiently when needed. But unfortunately, when it gets worn out, the overall system falls at the risk. Most probably, ball joints can be worn out if it is caught by dirt, grit, grease, less lubrication, and other impurities.

Worn out bearings

After some time and for reckless driving, wheel bearings will wear out. As a result, you can hear rapid vibration and stop the wheel from spinning. Additionally, a bad bearing can cause stress on the hub, the CV joint, and the transmission.

When the wheel stops spinning, there is a chance of a sudden accident and cause great damage to the overall system. There is also a cause when the wheel bearings are damaged, it tends to produce knocking noises.

Low oil level or pressure

Poor oil level prevents proper lubrication. Lack of oil or transmission fluid causes significant damage to the entire vehicle parts. When the oil level is down or low fluid level causes damage to the engine too. In the meantime, less lubricating tends to the overall parts to connect to the other parts at high speed. This is why the knocking noise arises.

Sway bar bushings break down or damaged

The sway bar link and bushing are almost interconnected. When the drop link gets faulty, the bushings can break down automatically. As a result, the knocking noise comes from the back. Stabilizer bushings help to lessen the noise and unusual bumps. Also, you can save your vehicle from rolling if the rubber bushings work fine.

How Can You Understand the Sway Bar Links Fault is Responsible for This Noise?

Here are some common phenomena to tell:

  1. Call your friend and tell him to sit in your car close to the door. Have a quick check and listen is there any noise from the wheels or bushings.
  2. Stay outside and shake the car from top to down. Then roll it up on different sides.
  3. Finally, ask your friend if he hears any noises. If he hears the noises, then it is most possible the sway or drop link is damaged.

How to Troubleshoot Knocking Noise From the Back of a Car

The problem of hearing mysterious sounds like knocking or clunking is painful. In this case, you should fix the problem as soon as you can. Here is a simple step-by-step guide to troubleshooting the issue.

Step 1: Diagnose the exact problem

Identifying or diagnosing exact problems is crucial before fixing them. If you notice rapid noises like knocking, rumbling, rattling, or any other unwanted noise, there might be some issues that are discussed above. So as an initial step, you should recognize the issue and then prepare yourself for fixing it.

Step 2: Gather the necessary tools

In the next step, you need to collect all the required tools and hardware for this project. You need to gather the following tools:

  • Jack stamps for lifting the car.
  • Sockets and spanner
  • Coil spring compressor
  • Hydraulic puller for removing wheel bearings.
  • CV boot tool.
  • Torque wrench
  • Ball joint separator
  • Strut nuts,
  • Tie rod puller, etc.

Step 3: Lifting up your vehicle

To get more clear inception and work easily, now, lift your car with a jack lifter. Be careful when lifting a car. Make sure you lift a car at standard height to work freely.

  • Take off some parts

Now, carefully remove the parts including the old strut, top mount, ball joints, dust boot, sway bar link, lower mounts, abs sensor, and brake line. In addition, there are a couple of bolts inside the car connecting to the struts that you need to take off. To remove all the parts, you can take assistance with individual tools.

  • Loosen the bottom mounts of the struts

Then to remove the struts completely, you should loosen the strut’s upper mount. You need to take help number 6 Allen to take off the sway bar link. 

  • Down the entire assembly

Then accumulate all the parts and replace them in the right place. All nuts and bolts should be attached in the right place. After that, reinstall the parts and make your car noise-free.

  • Clean the surface

Finally, clean the internal parts of the vehicle so that the dirt and grease are invisible. You can wash your cart for proper cleaning. If there is any dust inside, the dust boost or sway bar is again damaged quickly.


Knocking noise is common when any of the assemblies of the vehicle are damaged or worn out. But in most cases, you hear a knocking noise from the back of cars when parking is caused by bad struts or faulty wheel bearings. There are also some common reasons for hearing this noise that are already discussed in the body sections. So whenever you face this problem, first, diagnose the exact cause and then repair it ASAP.

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