Car Making Humming Noise at 40 Mph (Solved)

Is your car making a humming noise at 40 Mph?. Well, you’re not alone. Many people have come online in search of a solution to the problem.

Today, we will be looking at some of the possible causes of this noise and how to possibly fix it.

Unusual loud humming noise coming from your vehicle when you are on the road can cause any driver to panic. Therefore, it’s important to investigate the issue properly.

Car making humming noise when driving at 40 mph

Causes of Car Making Humming Noise at 40 Mph and How to Fix It

There are a couple of possible reasons why your car maybe making such loud noise. Below we will outline them and how you can possibly fix it.

Also Read:

Humming noise of car getting louder with increased speed (Solved)

1). Loose wheel Bearing

A car wheel bearing is one of the essential parts of the wheel assembly that connects the wheel and the axle.  It is consisting of steel balls or tapers that are held together by a metal ring and their primary function is to enable the wheel to rotate smoothly with minimum friction.

Therefore, if you are hearing louder humming noise from your vehicle as you increase the speed to 40Mph or above, the possible causes are either the wheel bearing or tires.

To identify the exact cause, you can take the vehicle for a test spin to determine the exact source of the sound. You can also have an experienced driver sit in the backseat and listen to tell you the place the sound is coming from.

You need to determine if the noise is coming from the front or the rear end of the car.

How to Fix the Wheel Bearings

Once it is established that the noise is from the wheel bearings and they are loose, you will need to tighten them by yourself if you are handy or take the car to a mechanic to fix it for you.

2). Uneven Worn-out  Tires

Any humming or mild grinding noise can be caused by poor tires. If the sound gets louder as you accelerate, the possible cause can be old or uneven tire treads. They can create such sounds when the car is speeding.

Feathered tires are often caused by bad suspension. If the suspension is weak, the tires may wobble on the road instead of rolling around smoothly. Over time, this can cause the tires to appear unevenly worn out.

How to fix the Issue

If you detect that the issue is with the tires, then replace them with brand new high-quality tires, not cheap ones. To prevent such issues in the near future.

Car tire

3). Faulty Driveshaft

Typically, a driveshaft should be straightly aligned and properly balanced. This makes it match your car’s speeds as the speed increases.

Unfortunately, if there is any rust or wear sign in it, it can cause the car to hum while you drive.

So, you should check the driveshaft for any imbalances. Generally, this issue can be fixed without the need to visit the mechanic shop.

How to Fix Faulty Driveshaft

If your findings are that the driveshaft is imbalanced, then you can try to straighten it out by yourself because it’s not difficult to do for men. Otherwise, you can take it to the mechanic shop for them to do it for you.

4). Leak in the Vacuum Hose

If after investigating the problem areas mentioned above, the issue still persists, then the cause might not be external but rather internal.

We can check the car’s vacuum hose for the problem. If you are hearing some vibrations or humming as the car goes to 40 Mph or beyond, then the problem might be the vacuum hose.

The function of the vacuum hose is to manage the air to fuel ratio to ensure optimum engine performance. therefore, any leak in the hose can choose the ratio to be improper and start to create noise due to poor engine performance.

One evidence that this problem exists is a decrease in fuel efficiency.

This issue can even be detected if the car is not even in motion at all provided the problem lies with the vacuum hose. So, if your car is making humming noise at 30 Mph or even 50 Mph, when driving, the cause can be the vacuum hose.

If left unchecked, this can cause further problems in your car. You might notice a decrease in fuel efficiency.

 You can try running the engines without accelerating to see if any sounds emit. This would help confirm whether the vacuum really is the problem or not.

Fix the Leak on the Vacuum Hose

If you found a leak in the vacuum hose, you’ve to run to a repair shop to get it fixed. Don’t ignore and continue driving with a leak in the vacuum hose.

How Much Would It Cost to Fix a Car’s Humming Noise?

The amount it will cost to fix a car humming noise will depend on the area of the car that is causing the noise. Generally, fixing the wheel bearing might cost you around $350 or more. Replacing the tires, each tire might also cost you $200 and more including the labor.

The vacuum hose cost also range between $150 to $950. Depending on many factors the cost will vary.

Final thoughts

While hearing humming noise at 40 Mph and beyond may not be a big deal, but is important to investigate the issue and fix it before it turns into a bigger problem.

Like I mentioned above, the sound could be from the wheel bearings, the tires, the vacuum hose or even the driveshaft. Any of them can cause the problem.

It is a good idea to start from the wheel bearing and the tires. Because they are the known common cause of car humming noise when driving.

If you can’t identify the problem by yourself, then you may need to consult for the services of a qualified mechanic to help you in identifying the main cause of the humming noise.

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