Car Makes Humming Noise When Parked: 10 Reasons

Why should I do if my car makes humming noise when parked? Here are the key reasons why this happens and what to do about it.

Every car owner loves to drive a car. The real issue begins when you hear some strange, peculiar sound from the vehicle. For instance, cars make a humming noise when parked. You may get panic after hearing the sound. But fortunately, when you hear such a sound, there is no issue with the vehicle. It is the sound of the fuel evaporation leakage check, and there is nothing to worry about.

Car Making Humming Noise When Parked

Humming Noise When Parked – Gas Cars

Sometimes you hear a humming noise from the back of the car after parking for a few hours in the garage. Well, that’s the sound of the fuel evaporation leakage test, and you don’t need to panic. The car has an evaporative emission control system (EVAP) which seals the vehicle’s fuel system and prevents fuel vapors from escaping into the ambient air.

The fuel vapors comprise hydrocarbon, which forms smog when in contact with air and sunlight, which is quite harmful. The evaporation leakage test uses the fuel pump to pressurize the vehicle system and test any leaks. Most cars are programmed to run this test after five hours of parking because every metallic will be contracted at that time, and it will be easier to find the leaks. If the car detects any leak, the check engine light on the dashboard will be on.

Humming Noise When Parked – Electric Cars

If you hear a humming noise from the electric car after parking for several hours, then it can be because of the coolant pump. The coolant pump circulates the coolant through various parts of the engine and radiator. It ensures that the engine is operating at a safe temperature.

But it starts working when you do anything on the car. For instance, if you notice the vehicle’s inside temperature is 50 degrees Fahrenheit, you turn on the app. It makes the car awake, and the coolant pump working starts. Finally, you hear a humming noise coming from the vehicle.

Other Strange Noises from Your Car and What They Mean

#1. Droning noise

Droning noise can come from the vehicle when the tires are in bad condition. It becomes more prominent while taking turns or at the time of accelerating. Tires are an essential feature of a vehicle. A new tire set will always give a smooth ride on the road.

But it can become wear and tear with time. But if the tires are damaged unevenly, you will hear a consistently droning sound. Sometimes the tires do not have enough pressure so you may hear a droning sound.

Please check the tires after hearing this sound. If the tires are underinflated, you need to add air. If you suspect feather tires(treads worn out unevenly), it’s better to replace them with new tires.

Car Making Humming Noise When Parked

#2. Squealing Sound

Sometimes you hear a squealing sound from the front end of the car. The sound becomes prominent as soon as you start the vehicle. The main reason behind the squealing sound is the serpentine belt. The belt runs over various pulleys and wheels. It can even run on the vehicle’s compressor, alternator, or pulleys.

The belt can get damaged after consistent use, resulting in a squealing sound. So, if you hear such a sound, inspect the belt instantly. If you don’t do this, the belt may fall from the compressor or alternator, and the air conditioning may stop working. Sometimes the car can even stop in the middle of the road, which is quite dangerous.

#3. Rattling Noise

You may hear rattling sounds from the car while driving over the potholes or bumps. Various things are happening in the front portion of the vehicle. Apart from the engine, there is a suspension system with various significant components on the car’s front end.

A rattling noise can come because of bad bushings. The purpose of bushing is to limit vibration, lessen noise and friction and absorb bumps on the road. These bushings are comprised of rubber. But they can be broken with time, so you hear a rattling sound from the car.

However, there can be other reasons, too, like struts, ball bearings, or sway bar links that can get damaged with time. It’s challenging to pinpoint the components from where the rattling noise is coming. You can do a bounce test at home when the car is in the parking position.

Press the vehicle strongly on the front end of the car. It may not tell you exactly which bushing is in bad condition, but it can definitely tell you whether the suspension system is the culprit or not for hearing the rattling sound. If you hear the noise on each bounce test, take your vehicle to the local mechanic.

#4. Squeaking Or Whining Sound

If you hear squeaking, groaning, or whining sounds while turning the steering wheel, it can be because of low-power steering fluid. The power steering system in old cars requires fluid to operate properly. If the fluid is low, turning the steering wheel becomes hard. Additionally, you hear such squeaking or whining noises. You can top off the power steering fluid reservoir and solve the issue.

Well, there can be other reasons too. For instance, the power steering pump can fail, and air can flow into the lines, which can cause squeaking or whining noise.

Car Making Humming Noise When Parked

#5. Screeching Or Growling

If you hear a screeching or growling sound while stepping on the brakes, then there can be a problem with the brakes on the car, which is dangerous. Brakes are a pretty important part of the vehicle. If the car is making large noise on stepping the brakes, then that indicates that the brake pads have gone damaged.

But if it is making a slight screeching or growling noise on putting feet on brakes, then that indicates that the brake pad is going to damage, and the caliper is grinding with the rotor. You need to change the brake pad in both cases.

#6. Loud Bang

Hearing a loud bang similar to a firecracker or gun sound from the car’s rear is quite frightening. In most cases, the reason can be an improper mixture of air and fuel in the combustion chamber. There can be more fuel and less air in the chamber, resulting in a loud bang sound.

Well, there can be other possible reasons too. For instance, there can be an issue with the sparkplug. Hearing such a loud bang sound indicates that the engine is running efficiently. If you don’t fix the issue earlier, the car’s exhaust system can be completely damaged. So, we will recommend you take the car immediately to a licensed auto repair shop.

#7. Rumbling

You may hear a rumbling sound along with vibrations when the vehicle is idling. It indicates various possible reasons. An incorrect air-fuel mixture in the combustion chamber can be the reason for this issue. The fuel injectors may go dirty with time and cannot provide proper fuel to the combustion chamber.

Additionally, if the air filter becomes dirty, there will be no oxygen in the chamber. Well, you can correct it by replacing the air filter.

Sometimes the oxygen sensors go bad with time, which may be the reason for hearing the rumbling sound. There can also be an issue with the spark plug. If the sparkplug does not burn the air-fuel mixture consistently, you will hear a rumbling sound.

#8. Knocking

You may hear a knocking sound from the engine hood of the car. The engine functions appropriately when all the fuel inside the combustion chamber burns simultaneously. But if all the fuel doesn’t burn simultaneously, that results in a knocking sound. Sometimes if you use fuel of low octane number, then also you will hear knocking sound from the car hood.

#9. Sounds Like Washing Machine is Running On High Spin

The condition is severe if you are driving and hear a sound from the vehicle, like a washing machine running at high speed. The lug nut can have a problem, which indicates that the car’s wheels are not secured. So, take the vehicle to the nearest mechanic as soon as possible.

Car Making Humming Noise When Parked

#10. Roaring Sound

You may hear a roaring sound while accelerating your car. There can be some possible reasons for it. For instance, you will hear such a sound if there is an issue with the catalytic converter.

All the exhaust gases usually go through the muffler, reducing the roaring sound. But if there is a crack in the exhaust system, the gases will escape before they reach the muffler, so you hear a roaring sound. 

Frequently Asked Questions

#1. Why is my car making a whining noise when idling

If you hear a whining noise when the car is idling, it indicates some engine components have broken or been damaged badly. There can be other reasons too, like if there is an oil leak or the valves are stuck, you will face such a problem. You need to take the vehicle immediately to the nearest mechanic so that he will detect the issue and correct it accordingly.

#2. Why does my car make a noise when I am stopped?

There can be many possible reasons for cars making noise while stopping. For instance, friction on the brake pads can get worn away with time, and it grinds across the rotor’s surface, producing sound. Again, keeping an item on the door panel pocket or cup holder will make a sound.

#3. Would a transmission make noise in the park

If the car transmission makes noise in the park, it can be because of damaged needle bearings in the transmission torque converter. You will have difficulty shifting gears. Again if the transmission fluid leaks, you will also hear the noise. So, the car should have the proper amount of transmission fluid.

Sometimes, some unscrupulous used car mechanics might put sawdust in the transmission to mask noises. If you have just bought a used car, you might want that checked out.

Car Making Humming Noise When Parked

#4. What does a failing transmission sound like

The transmission is quite an essential part of the vehicle. It helps transfer power to the wheels so the car can run at the desired speed. If any problem occurs in the transmission, then it can put risk to the driver and passengers sitting inside the vehicle. When the transmission fails on your car, you will hear clunking, whining, or humming sounds. Take the vehicle immediately to the local mechanic for repair.

Wrap Up

Hearing strange sounds like whining, grinding, or knocking sounds from the car can make you panic. It’s best to take the vehicle to the nearest mechanic as soon as possible to detect the issue. But if you hear a humming sound after parking the car for several hours, there is nothing to worry about. Thank you for reading this article.

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Sean Mendez

Hi, I am Sean, a self-confessed petrolhead. I live in Boise, Idaho with a busy family of four and our energetic Labrador retriever. Thank you for visiting my website. You can find my email on the contact page.

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