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Home / Symptoms / Humming Noise

Hey, Why Is My Car Making A Humming Noise While Driving?

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Humming Noise While Driving has different causes, the top 4 are A/C Failure, Differential Issues, A Fault Wheel Bearing or Tire Cupping.
Humming noises from your car mean it’s trying to get a message to you. The message will depend on you gathering some information for proper translation. Take note of how to duplicate the noise. Does the humming change with road speed? Does the noise change when you’re at speed and slightly turn left or right? Does the noise occur only on acceleration, change on deceleration and not exist when you coast along? These are just a few clues to share with your trusted shop.

Common Causes For A Humming Noise When Driving

A humming noise from the car can have different origins; it's typically friction-related and has a large pool of root possibilities. However, these are the most common causes:

  • Tire cupping: Tire cupping is when the tires become uneven. The tread patterns typically show a bumpy wear pattern resembling a cup or orange surface. So, when the car moves, those irregularities press against the road, making odd vibrations and noises.
  • Faulty wheel bearing: Wheel bearings are components behind the wheels that help them rotate on a metal rod below the car called an axle; this is also part of the steering system. However, the wheel bearings can have issues like overwear and lack of lubrication, causing extra friction and producing a humming noise.
  • A/C failure: An air conditioning (A/C) failure can create changes in the airflow efficiency. If the compressor responsible for blowing the air through the AC vents fails, it'll likely produce a humming sound.
  • Differential issues: The differential helps the wheels rotate on a metal rod below the car called an axle; they're essential for helping the wheels turn and get good road traction. However, they can have issues like a lack of lubrication and worn bearings that generate extra friction, causing a humming sound.
  • Faulty fan clutch: A fan clutch is part of the car's cooling system; it controls the cooling fan that prevents the engine from overheating. However, it can become erratic or even stuck, creating a humming fan noise.

When driving at high speeds, a car humming noise can become an alarming distraction for many drivers. Note that dirt roads typically mask these types of noises. The humming noise might come with a grinding noise. Still, there are different symptoms to keep track of if you catch your car producing a humming noise.

Let's Get To The Bottom Of It!

Is the sound more like a roar that changes depending on the road material?

The sound resembles a roaring sound and is more evident on hard concrete or grooved pavement. In this case, it sounds different depending on the road surface and won't change the tone if you slightly swerve side to side. In this case, the problem might relate to tire cupping.

Does the noise pitch change when you swerve?

When swerving side to side, the noise's pitch changes and the car's steering feels looser than it normally would. In this case, the car's weight shifts when swerving, causing the bearings to make a noise. So, the problem might be a faulty wheel bearing.

Does the sound appear when you turn the air conditioner on?

A humming noise escapes from the engine bay, varying depending on the vehicle and engine's speed. In this case, the sound only appears when you use either the air conditioning or defrost system.

Does the sound change according to speed?

A humming noise comes from the vehicle's rear, getting louder as speed increases. Then, the sound goes away when coasting, and it gets different when you slow the vehicle down. This type of behavior relates to differential issues.

Do you feel like the sound is coming from under the car's hood?

A humming noise comes from underhood, similar to the sound of a plane taking off. This sound appears whenever you're driving at high speeds and affects the car's performance. In this case, a failing fan clutch is the most possible culprit.

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Vehicle Health Inspection Proof

Explore the following typical inspection results that show a potential cause for the symptom and select the one you believe is similar to your vehicle's issue.

Air conditioning internal failure

When doing an underhood inspection, the mechanic saw that the A/C clutch is slipping and the air compressor is making noises. In this case, replacing the air compressor to restore proper operation with no noise will be the service focus.

Apart from a faulty wheel bearing, a car might be going through air conditioning internal problems, leading to a weird humming noise.

In the case of a refrigerator leak, the car will lose vital refrigerant oil for its air conditioning compressor. As a result, the air conditioning will have an internal failure, producing a relatively loud humming noise in the car's interior.

Alternatively, the air conditioning's internal compressor might fail because of high pressures due to the outside temperature. Then, the car makes a humming noise.

A condenser fan failure can also get you the same consequences. It might happen because of debris and leaves restricting the condenser's airflow.

In this case, the mechanic will perform an in-depth inspection, checking for refrigeration fluid leaks and overall damage to the air conditioning system.

Failing fan clutch engaging constantly

When inspecting under the vehicle's hood, the mechanic spotted a fan clutch not letting the fan spin free and some back-and-forth play when trying to move the fan. It's time for a replacement to eliminate the noise and protect the water pump and other parts from vibration damage.

A fan clutch might seize and start working non-stop, cooling off the engine beyond normal. In this case, your car is at risk of having fan motor or water pump bearing damages, as well as radiator issues if the blades stretch too much, even risking a plastic fan shattering.

The fan clutch drives the engine cooling fan that you'll find close to the radiator.

Excess fan noise getting louder with speed is a pretty common symptom of this type of problem. The sound is similar to a humming noise.

As mentioned before, this problem can happen mechanically, with the clutch suddenly seizing. Still, an electrical failure might also be the culprit.

Apart from a complete underhood inspection, the mechanic should perform a digital vehicle health inspection to cross out electrical failures.

Loose/worn/damaged wheel bearing affects the vehicle when braking, often causing the steering wheel and the entire body of the vehicle to shake

The mechanic saw a loose wheel hub while inspecting the vehicle on the rack. Also, he noticed loose movements and noises when spinning the wheel. The red arrows in the image indicate the directions in which the wheel was wobbling while spinning.

A failing wheel bearing can cause humming noises and vibration when braking at high speeds. Typically, if that's the case, you might also notice buzzing sounds. In addition, banging noises or steering wheel vibrations might happen if this problem builds up.

The wheel bearings are under stress while you're driving since they support the vehicle's total weight. Unfortunately, they will wear out eventually, indicating it through a humming wheel bearing noise.

A wheel bearing sits inside the vehicle's actual wheel hub or axle housing. This part is a set of steel balls hugging each other tightly inside a metal ring at the deep center of the wheel's hub.

More precisely, you'll find the wheel bearing inside a hollow piece of metal known as a hub.

Inside this hub, the wheel bearing attaches to the steering knuckle or axle, reducing friction while the wheels are spinning. A faulty wheel bearing might affect the performance of the car's brake pads.

To improve the life expectancy of your car's wheel bearings, you can avoid bumpy or tricky terrains, speeding — especially on sharp curves —and putting too many heavy loads on the car.

An additional factor that can lead to loose or worn wheel bearings is uneven wear and wheel alignment in the vehicle. A car's bad alignment will make for a defective wheel bearing faster.

Car leaks can signify the loss of lubrication fluid, which can result in bad wheel bearings. Without lubrication, this part wears out faster, resulting in a bad sound from the wheel bearing.

In this case, the technician will perform a complete inspection, checking out the wheel alignment, uneven tire wear, and defective wheel bearings. Then, the mechanic will replace the wheel bearings that were worn out or loose.

Additionally, the mechanic might also look for leaks in the car.

Finally, he'll check the steering wheel's straightness — a well-centered steering wheel is important — after correcting the car's bad wheel bearing problem, ensuring there's no vibration or humming noise left.

Alternator bearing failure causing humming noises from underhood and triggering electrical problems

Part of a Vehicle Health Inspection is listening for different noises when the engine is running. In this case, the alternator bearings were failing and making noises. Mechanics have a keen ear to detect these problems early since they've been listening to these sounds for a long time.

A premature bearing failure on the alternator can sound like a loud humming noise, even resembling a grinding sound at times. It can also result in dim headlights and other electrical issues.

This type of problem can happen because of improper belt tensions on the alternator, interfering with the rotor's spin. Alternatively, dirt and debris can break down the pulley de-coupler — which allows the rotor to spin inside the stator —, resulting in the same problem.

In this case, the technician will check your car's underhood section and perform an inspection on the alternator, which typically sits close to the engine block.

Differential issues

Part of the Vehicle Health Inspection is a short test drive plus checking all fluid levels. A noise appeared on the test drive, and the failure was obvious when the car was on the lift to inspect the differential fluid condition. Differential damage has been noted.

Humming noise issues in the differential usually involves a failing ring, pinion, and related bearings.

You can spot the differential between the vehicle's wheels, where the drive shaft unites with the axle. It can sit on the front, back, or both axles of your vehicle, depending if it is front-wheel, rear-wheel, or four-wheel drive.

The differential's main goal is to make the drive wheels spin at different rates. So, the outside wheels need to spin faster since it travels farther from the inside wheels. This all happens inside the differential, allowing you to make safe turns.

To access the differential, technicians will lift your car and check its underside. It's common to mistake this type of problem for a suspension noise since it comes from the car's underside.

Usually, this type of problem carries specific symptoms, there will be different tones when accelerating, decelerating, or coasting, one of which is a clunking or clicking noise every now and then, which might signify a broken ring or pinion gear. Additionally, it might also inffluence the power steering pump.

The symptom above commonly follows a humming noise, much like a howl or whine, when driving straight. In addition, it's vital to pay attention to your car's sounds when decelerating.

Humming noise when you're speeding up or slowing the vehicle down is an indication of a bad or loose pinion bearing.

Improper engine mount

Part of the Vehicle Health Inspection is a quick engine and transmission mount check. When looking under the hood, the mechanic found that the worn mount is allowing metal contact between the engine and the car body, causing noise and vibration.

An improper engine mount can cause unhealthy vibrations on the engine frame, which affects all engine components.

Apart from the humming noise, a failing engine mount commonly makes "impact noises." In addition, clunking, banging, and rattling sounds signify that the engine might be very loose, which is alarming.

After starting an engine, you'll typically feel stronger vibrations when the vehicle is in Drive or reverse; this is because a failing engine mount's anti-vibration properties don't work well. Then, the engine is at risk of making contact directly with the metal frame when accelerating.

As a result, it's common to notice a humming noise getting louder with speed. In this case, the mechanic will do an underhood inspection and assess the lousy engine mount. IN extreme cases, the engine might develop internal damage, affecting the exhaust system, which also causes the noise.

Tire cupping

During the Vehicle Health Inspection, the mechanic saw cupping on the tires making a humming noise at high speeds. Tire replacement will clear the noise, but the suspension needs to go through inspections and repairs to protect your new tires.

Uneven tire wear and tire cupping can produce humming noises at a constant velocity, which ends up getting louder with speed.

A tire noise usually involves uneven tire wear because of wheel alignment and driving methods. This damage can progress differently depending if you use winter tires with a large tread block pattern.

Tire cupping can happen because of lousy suspension, crooked steering angle, or poor wheel alignment. In this case, the car's alignment might be out of hand, causing excessive wear on the wheels.

Consequently, the affected wheel will impact your handling of the car. It's common for drivers to struggle when driving a straight line, even at highway speeds.

A worn tire tread is particularly dangerous during winter in snowy areas, risking slides.

So, keep an eye out for uneven tire wear and improper wheel alignment since it indicates the humming sound's culprit. To precisely detect suspension and steering problems, the technician takes into consideration which wheels of the vehicle have a damaged tire.

Take your car to the shop, and the technician will assess any improper wheel alignment related to the tire noise, tracking any suspension components that need a fix. By the end, the mechanic will replace the old tires with new ones.

Typical Makes

That need Humming Noise significantly more often than average vehicle makes

  • Make: Jeep
  • Model: Compass, Patriot, Grand Cherokee, Commander
  • Struts
Strut Assembly
  • Make: Chevrolet
  • Model: Tahoe, Suburban, Silverado 1500 1/2 Ton, Suburban HD
  • Wheel Bearing & Hub Assembly, Compressor Replacement, Fan Clutch, Alternator
Alternator
  • Make: GMC
  • Model: Sierra 1500 1/2 Ton, Yukon, Yukon XL 1/2 Ton
  • Wheel Bearing & Hub Assembly, Compressor Replacement, Fan Clutch, Alternator
Wheel hub and bearing
  • Make: Toyota
  • Model: Avalon, Camry, Tacoma
  • Engine Cooling Fan Assembly, Control Arm
Fan assembly
  • Make: Ford
  • Model: Transit-150, Transit-250, Transit-350, Expedition, F150 1/2 ton Pickup, E150 1/2 Ton Econoline - Van
  • Differential Ring And Pinion Gear Kit, Axle Bearings, Pinion Bearing
Ring and pinion
  • Make: Dodge
  • Model: Challenger, Charger
  • Control Arm - Front Lower
Control arm with ball joint

Typical Fixes to Address the Cause(s)

The following chapters bases themselves on experiences from our auto repair shop; we'll describe related problems' causes and fixes.

Sometimes a problem is more challenging to describe than it initially looked like. If you are not sure your problem is described by this article, please find below similar vehicle symptoms, which might describe better the issue you are experiencing.

Vehicle Symptoms

Below are just a few examples of typical Symptoms and Fixes your car might be experiencing

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Four common causes for vehicle stuck brake pads and their related parts.

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Four common causes for a vehicle with a Bad Brake Caliper and their related parts.

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Four common causes for a vehicle shaking at high speeds and their related parts.

Hey, Why Is My Car Shaking At High Speeds?

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Typical Fixes Pages