Reasons Why Car Makes Humming Noise From Engine

Reasons Why Car Makes Humming Noise From Engine

Driving a car that makes noise from the engine is a nuisance. It takes away the enjoyment of driving your pride possession.

There are usual noises that a car is expected to make. However, it would be best not to ignore others as they indicate something is wrong with your car.

Humming noises coming from your car engine when you’re driving, idling, or accelerating indicate different problems and should be checked by a professional.

Car Making Humming Noise from Engine

In most scenarios, if you encounter humming sounds when driving, there could be a problem with components such as bearings or transmission.

This article discusses several causes of humming noises from the engine and how you should handle them.

What Causes Humming Noise From Engine?

Low Transmission Fluid

Low transmission fluid in the engine can cause humming noises when driving. These sounds become louder when accelerating.

In most cases, leaking is the leading cause of low transmission fluid levels. You can suspect fluid leakage and check for a trail underneath the car.

If the transmission fluid is leaking, you will notice a red fluid with a slippery consistency under your car.

And though the leak could be coming from other car fluids, you may know if the low transmission fluid is the cause through these symptoms:

  • Difficulty shifting gears. If you have difficulty changing gears, maybe shifting too late or even too soon, you might want to check the transmission fluid levels.
  • Gear slippage. Gear slippage is one of the symptoms of having low transmission fluid. Gear slippage means the gears will not engage and accelerate properly.
  • Overheated transmission. Low fluid levels cause friction in the transmission, causing them to overheat and generate the hum. You can tell that the transmission is overheating if you notice a burning smell.


Having low transmission fluid can be caused by:

  • Torque converter failure
  • Infrequent check
  • Axle seal failure
  • Transmission gasket pan damage or failure


If the issue is with the torque converter or a damaged transmission gasket, you should replace them with new ones. You can remedy axle seal failure by pulling out the damaged seal using a seal puller and replacing it.

It’s essential to check the transmission fluid level regularly. You can do this by using a dipstick.

However, if your car doesn’t have a transmission dipstick, you should have it checked by professionals.

Wheel Bearings Issues

It can be hard to determine whether the humming sounds are caused by tire or wheel bearings. But, you can quickly know by steering the wheel to either side, like when changing lanes.

If the noise worsens, it’s probably an issue with wheel bearings. The humming­­ noise also intensifies when you accelerate.


  • Poor road conditions. Uneven roads with potholes, bumps, and dirt tracks often affect wheel bearing. These put a lot of strain and elevated friction on the bearings causing them to produce humming noises from the engine.
  • Unbalanced tires. It is simple. If your car tires are unbalanced, the strain you put on the wheel bearings will take a toll on them. If left unserviced, the bearings wear out faster and could cause damage to other parts.
  • Poor installation. Failure to install the bearings as per the manufacturer’s instructions will likely cause problems.


You can easily replace damaged bearings without seeking professional help. All you need to ensure is that you have the necessary tools.

Bad Catalytic Converter

The catalytic converter is located in the exhaust system and converts pollutants and toxic gases into less toxic gases. Over time, the catalytic converter can become damaged, overheated, or even have rust.

Catalytic convertors overheat due to the exhaust system’s excessive amount of unburned fuel or gasses. A leak in the exhaust system can also cause the catalytic converter to overheat.

It leads to poor performance of the engine, and it may eventually shut down.

You can know your catalytic converter is bad through these symptoms:

  • Poor fuel economy
  • The smell of rotten eggs coming from the exhaust
  • Poor engine performance
  • Poor acceleration
  • Failed emission/ smog test

Causes Of Car Making Humming Noise from Engine


While the above symptoms could help you know whether the catalytic converter is bad, you need to inspect it physically. It is to make sure that it is the source of the humming noises.

You can have someone rev the engine for you as you check under the car. The catalytic converter is located between the muffler and the engine.

If you are sure that the catalytic converter is the cause of the humming noises, you can either replace it or fix it without replacing it. You can fix it by cleaning the convertor off the contaminants.

Failing Differential

Front and rear differentials improve handling. When the differential is faulty, you have a hard time going around a corner.

The humming sounds coming from your car could indicate a failing differential. A bad differential could mean that the gears are worn out, which causes humming sounds.

Also, if you hear vibrating sounds coming from the driveshaft, know that the differential is failing, and you need to have them detailed. These vibrations intensify when you slow down or when you accelerate.


  • Using the wrong oil
  • Lack of lubrication due to lack of oil
  • Aging or normal wear


If you want to extend the differential life, you should regularly service it. An expert will notice problems with your differential and have them fixed before they become worse.

You should also ensure you’re using the correct type of oil. And regularly check the oil levels to ensure it of the right level and condition.

Steering Problems

If the steering system has issues, you will likely hear humming sounds. These issues include a loosened steering belt and a misaligned steering wheel.

When the belt becomes loosened, accelerating the car creates a humming sound. It puts you in danger since it is prone to cause an accident.


  • Steering fluid leakage
  • Poor alignment
  • Low steering fluid
  • Worn-out belt
  • Damaged tie rods
  • Bad tire pressure


You should always check the power steering fluid level, which always causes steering wheel problems. Also, check out for leakage and tire air pressure.

The tire pressure should be in line with the recommended psi. Lastly, always have your car serviced by reputable companies to avoid defective installment of components.

Exhaust System Problems

The reason you are hearing humming sounds in your car could be because the exhaust system has problems. In rare cases, your exhaust bolts could be loose and cause hum noises when driving.

Another problem could be that the exhaust pipe is not well placed or fixed and interferes with other components’ functionality.

Most of the humming sounds become louder when you accelerate. However, issues to do with the exhaust system are different.

If your exhaust manifold gasket is damaged or the oxygen sensor is loose, the noises tend to go away when the engine warms up. But, you shouldn’t overlook these sounds as they will only worsen the situation.


  • Rust
  • Faulty oxygen sensor
  • Bad muffler


Rust in the exhaust system is caused by moisture obtained from the chemical reactions and rain. A corroded exhaust system is prone to leaks, creating more problems for you.

You can have it fixed by mechanics or DIY it at home using vinegar. A skilled mechanic for quality results can replace your muffler and oxygen sensor.


It would be best if you did not overlook the humming noises coming from the engine. Many car problems create the humming sound, and knowing which problem you’re dealing with is essential to fix it.