Humming Noise

Humming Noise

I hear a humming noise coming from underneath the vehicle between the cab and bed of truck when running. What could this be?
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :

The fuel pump in the fuel tank is the humming noise you are hearing. The pump will begin to become noisey if the fuel filter becomes clogged restricting the pump volume and pressure. If the pump is starting to go bad it will become noisey also. The fuel pump and filter should be replaced.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

The most major issue that a humming noise can mean is a failing alternator. The alternator is responsible for keeping your car`s battery charged and electrical system working, so you should get it repaired immediately.

If your car makes a humming noise, it could mean the differential needs lubricant, the transmission is failing or the universal joints or wheel bearings are wearing out. What to do about it: Pay close attention to what happens before and when your car starts making the sound.

A humming sound heard at idle has to be something that moves even while the car doesn`t. This could be a drive belt or one of the components driven by the drive belt, such as the power steering pump, air conditioning compressor, water pump, or one of the idlers that hold the belt in place.

Common reasons for this to happen:

Low Transmission Fluid: For both manual and automatic transmissions, the primary cause for whining when in gear is low transmission fluid. If the fluid is too low, then the internal components of the transmission are not lubricated properly.

If there is a humming noise coming from the transmission, then either a clutch is slipping or a drive shell is broken. First check the fluid to the transmission and make sure that its full and red in color. I recommend servicing the transmission with new oil and a new filter to see if the noise goes away.

If the sound resembles humming, buzzing, or clunking, you may be experiencing transmission failure. Bad automatic transmissions may emit humming, buzzing, or whining noises while manual transmissions have harsher “clunking” sounds.

Solutions: Ground loops are easily recognizable as hum in the loudspeakers. To eliminate the ground loop hum, the AC loop must be broken. The easiest solution is to connect all audio equipment to a single AC outlet, using a power strip (featuring a surge protection) or using a power conditioner.

Your Car Makes a Humming Noise When Accelerating

If you hear a rumbling/humming noise as you idle and when you accelerate, the noise gets louder (like an airplane taking off) this is most likely a wheel bearing issue. What it could mean: This wheel bearing noise is often mistaken as engine noise.

A: Noise is the most common symptom of a bad wheel bearing. However, there are other potential signs as well, such as vibrations while driving. At low speeds, you will be able to feel the vibrations, while at higher speeds, they`ll manifest as humming sounds.

A humming or whining noise in an automatic transmission vehicle often means that you are low on automatic transmission fluid. If this is the case, you want to refill that fluid immediately. Transmission fluid reduces friction, which means heat, which in turn is bad news for transmissions.

When you hear a high-pitched squealing sound coming from under your hood, you may need to check your vehicle`s serpentine belt for cracks and wear. Many cars have multiple belts, and each one will need to be checked to ensure they are in good working order.

A crackling or humming sound is generated by small electrical discharges, often caused by water drops that collect on the conductor when it rains or when there is sufficient moisture in the air.

This hum, or discharge of energy, happens when the electrical field around the power lines is greater than what is needed to start a flow of electric current from the power line to the surrounding air. The likelihood of that happening can depend on the weather, as water increases the conductivity of air.

A hum is a sound made by producing a wordless tone with the mouth closed, forcing the sound to emerge from the nose. To hum is to produce such a sound, often with a melody. It is also associated with thoughtful absorption, `hmm`.

Grinding Sounds

The automatic transmission relies on the proper operation of a planetary gear system. If the gear system has an advanced problem, you may hear grinding sounds coming from the transmission, and the transmission could already be damaged.

Tinnitus. A suggested diagnosis of tinnitus, a self-reported disturbance of the auditory system, is used by some physicians in response to complaints about the Hum. Tinnitus is generated internally by the auditory and nervous systems, with no external stimulus.

Droning. A droning noise that gets louder as you accelerate may be coming from your tires—particularly if they`re old or worn. It could also be a sign that you have “feathered” tires, meaning the treads are wearing unevenly. Your tires are an important safety feature, so get them checked.

A low-pitched humming coming from under the car could mean a failing transmission, worn universal joints, a bad wheel bearing, or a worn differential. A car humming noise from the tires usually means uneven wear or damage, while a grind from a wheel (without the brakes applied) is the sign of a failing wheel bearing.

Once you notice any sign indicating a bad wheel bearing, avoid exceeding 500 miles with that issue. A failing wheel bearing will increase your difficulty in driving. But with a high-quality wheel bearing, you can drive for another 1000 miles as per the estimate.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Replaced water pump (no noise before just leaky) now there’s loud humming noise and I don’t have heat. Haven’t tried driving yet.

ANSWER : Hi there. From the description you have provided, you replacing the water pump and now you have a new noise and no heat, are an combination of things going on. First, the loud humming noise coming from the water pump/timing area concerns me. Assuming, you followed the repair procedure properly for the water pump replacement. It could be, the replacement water pump is faulty. Something is amiss and needs to be corrected before you go out and drive your vehicle. The noise could result into a catastrophic and an expensive repair. Second, no heat could be, there is air trapped in the heater core and needs to be bled and/or flushed. I recommend having your vehicle’s no heat and humming noise be diagnosed and repaired by a certified technician, such as one from YourMechanic.

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My E350 is making a loud humming noise but it you can’t hear it outside the car.

ANSWER : Hi There,
This may be caused by a couple of different things such as a water pump that may be starting to fail or possibly an alternator that is beginning to go bad. Either of these will produce a bit of a humming or whining noise that will change as the engine RPM increases or decreases. I would suggest having a professional from YourMechanic come to your location to take a look at your vehicle to properly diagnose and repair.

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on/off humming sound over 65mph

ANSWER : A "humming noise" while driving at speed can be caused by tires or wheel bearings. If you drive with the window open and you hear the noise outside the car, like the sound bouncing back at you from a wall, highway divider, etc, then it’s most likely your tires.

Also, if you run your open palm across the tread surface of the tires and you feel a choppy pattern, like if you made a fist and ran your opposite hand across your knuckles, that’s another sign that the noise may very well be from the tires.

When driving with the windows closed, if you hear the noise change volume or pitch when say, changing lanes, then it it most likely one or more wheel bearing.

If you’d like to get this fixed, consider YourMechanic, as a certified technician can help you diagnose the source of the noise and make the necessary repair. Good luck.

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Humming noise coming from Right Front hub, click noise in the steering gear – What is the problem? 2004 Cadillac Escalade

ANSWER : Hello – I believe the humming noise you mention in the right front wheel area is a worn front wheel bearing/hub assembly. If the noise is louder when turning left while in motion, that would confirm the diagnosis. I would recommend having the right, front wheel bearing replaced by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs. The clicking noise while turning the steering wheel may be a problem with the upper steering shaft in the steering column. Cadillac has issued a technical service bulletin for problems with the steering performance (# 232985). Check with your Cadillac dealer service center for more information on this repair.

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When I turn my car slightly to the left, I hear a humming noise almost like a rubbing noise. The steering wheel doesnt vibrate

ANSWER : The noise could be from the wheel bearing rubbing as it may have dry grease inside the bearing. The noise also could be the power steering pump as there is a load applied to the pump more than steering the other direction. Also, check the tires on the vehicle and see if the tread is rubbing on the fender or the frame as if the tires may be too wide for the steering of the vehicle.

If you need further assistance with the vehicle making a rubbing noise when turning to the left, then seek out a professional, such as one from Your Mechanic, to help you.

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Humming noise, wheel bearing issue, and two evap leaks

ANSWER : Regarding the right, front wheel bearing, you can confirm this diagnosis by turning left at moderate speeds (i.e. freeway on-ramp). The noise will increase during the turn (which loads the right front wheel bearings).

Regarding the squeal while turning the power steering pump, this could be a low steering fluid level and/or a serpentine belt that is worn or has a loose tensioner. The "smoke test" your mechanic mentions is a standard way of testing for "evap" (aka air intake) system leaks. The other approach is to spray starter fluid around rubber hose connections in the intake while the engine is running. If the idle speeds up, you’ve found a leak.

A professional mechanic, such as one from YourMechanic, can replace the front wheel bearing, determine exactly why the Check Engine Light is on, and suggest any needed repairs to get your car back in proper working order.

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Car noise at higher speeds on slightly rough roads

ANSWER : Hello there, many different items can begin to cause noise at this type of speed. In many cases this is not noticed as the highest speed limits in most areas is 85 MPH. The most likely cause is body noise, interior panels rubbing, struts, wheel bearings, or the tires themselves.

If you’d like a second opinion on this, consider enlisting a qualified technicians who can diagnose the sound you’re hearing. An accurate repair can then be made once the issue has been pinpointed.

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What would my next step be? Wheel bearings are driving me crazy!!

ANSWER : This is a common sound when wheel bearings are badly worn and need to be replaced. When they wear out, the bearings begin to grind metal on metal which as you know creates an intense heat. This can be dangerous as they may potentially seize up while driving or in extreme cases, they can catch fire.

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