Clunking Noise When Accelerating & Decelerating – Probable Causes

Updated: | Author: Steve Freling | Affiliate links may be present.

Are you hearing a clunking noise when accelerating and decelerating? Are you afraid that your car may be about to blow? Is this all just an elaborate excuse to justify buying a new car?

Whether you think it is a big or small problem, a clunking noise should never be ignored as even the small problems tend to cause even bigger problems “down the road.”

There are many common problems and solutions related to the classic clunking noise. The “culprit” can be anything from low transmission fluid to a worn-down driveshaft. However, before taking your car to the mechanic, you’ll want to rule out the simple solutions like adding more transmission fluid or tightening a loose bolt.

Transmission Fluid

One common problem that results in a clunking noise is low or bad transmission fluid. A lack of proper transmission fluid means that there are moving parts not getting enough lubricant. This can cause these parts to be ground down or even break.

To check to see if this is the problem, you will need to pull out your transmission dipstick. If you find that your transmission fluid is low, then you’ll just need to add more. However, you’ll also want to examine the color of the transmission fluid.

If the transmission fluid is any color other than red, then run for the hills! Don’t worry, it won’t blow; but, the fluid does need to be changed. You’ll also need to replace the filter as it has failed in its duty and an example must be made.

Loose Bolt

Another common cause for a clunking noise is a loose bolt. While it is a simple fix to retighten the bolt, it is a difficult quest to find the culprit.

Your best bet is to get an idea of where the sound is coming from and then to check for any loose bolts in that area.

One common area that you can check is your engine or transmission mount. This is especially the case if you hear the clunking increase when there are any sudden turns, acceleration, or deceleration.

To keep this problem from happening again, I recommend threatening the bolt with replacement if it fails in its duty to securely fasten the thingy-ma-jig to the other thingy-ma-jig.


The wheel: a great yet simple invention — until we decided to hook an engine to it. As a result, there could be a number of culprits in the “wheel area”.


First, if your car is noticeably leaning forward when stopping or leaning back when accelerating, then your suspension is probably the problem and will need to be replaced as it is worn down and is touching parts it was never meant to touch.

Ball Bearings

There could also be a problem with the many ball bearings connected to your wheel. To check this, raise the car as if you were changing out a tire. Then, turn the wheel back and forth and observe the many ball bearings.

If a ball bearing is popping in and out of its socket, then it is worn down and needs to be replaced.

You’ll also want to examine the sealed cover over the socket. If it is not sealed, then water could be leaking in and ruining the ball bearing.

Loose Wheel

Another possible culprit is a loose wheel. To check, all you need to do is raise the wheel off the ground and see if you can wiggle it back and forth. You can also spin it to see if there are any unholy noises coming from it.

To fix this, you’ll want to tighten all the bolts and make sure that the “head” of the bolt is flush to the wheel when fully tightened. If it is not, then you’ll want to make sure the screw lining is intact and that the bolt is the right size.


If the clunking noises preceded a period of vibration, then you may be dealing with a driveshaft issue. Another sign that the noises may be coming from the driveshaft is if they are prevalent when shifting gears.

You can check for worn-out joints or a problem with the body of the drive shaft. If you do find that the driveshaft is the culprit, I would not recommend just replacing the universal joint on the driveshaft.

While the joint may be the culprit, it is reasonable to assume that if there is a worn-out joint, then the driveshaft itself is probably at the end of its life and will bring more problems in the future if you do not replace it.

So, while it may seem cheaper to just replace the driveshaft joint, it may lead to future problems that could have been avoided if you had replaced the entire driveshaft.

Final Thoughts

A clunking noise is never something to take lightly and ignoring it could result in more problems. So, if you cannot find the source of the noise, then you should take it to the mechanic for your own safety and that of your bank account.

Avatar photo

About Steve Freling

Steve has worked for more than 20 years as an automotive mechanic, and later run his own repair shop for both cars and motorcycles. He's a maintenance freak, and generally pretty good at troubleshooting!

1 thought on “Clunking Noise When Accelerating & Decelerating – Probable Causes”

  1. Hi there,
    I have an Au Xr8 2000 falcon and it has just started making a small clunking noise when releasing the exceleratior at low speed, say 20 to 40 kilometres. Mainly when in heavy traffic? Have any ideas what this could be?
    Thanks heaps


Leave a Comment