Car Alternator (Bearing, Whining, Humming) Noise

car alternator squealing, chirping, grinding, whining, humming, growling, buzzing, crackling sound

Strange sounds do not necessarily point to a defective alternator. Instead, they should encourage you to troubleshoot the following:

Belt-Related Noise: Squealing, Chirping, Or Grinding Sounds

The belt uses the engine’s power to drive the alternator. Therefore, it is vital to the alternator’s work. You may hear squealing, chirping, and grinding sounds because of the following:

  • A worn-out belt makes squealing and squeaking noises. A visual inspection will reveal cracks that misalign the belt because it cannot fit the pulleys properly.
  • The belt can dry out because of old age or heat from the engine, which leads to squealing since it cannot grip the pulley with the correct tension. This leads to slippage. Although, similar challenges can arise because the pulley is worn-out. Don’t blame the belt without first inspecting the pulley’s grooves.
  • Coolant is beneficial because it prevents overheating in the engine. Unfortunately, it can leak, contaminating the belt and producing squealing sounds.
  • Surprisingly, grinding sounds can also originate from loose and worn-out belts because they encourage the engine’s parts to knock against each other.
  • Are these sounds more prominent in cold weather? That matters because low temperatures damage the belt by making the material brittle. This increases the rate of wear and tear.
  • Many people blame misalignment on worn-out or damaged belts. However, sometimes mechanics make mistakes. They may install the belt poorly during a replacement, producing squealing and chirping noises.

How To Fix It?

Belts are probably the simplest problem to solve in a car with strange noises. Keep the following in mind:

  • Consumer Reports expects a serpentine belt to last 50,000 miles. You should expect failure once the belt crosses this threshold.
  • If you’re hesitant to replace the belt after 50,000 miles, inspect it. You’re searching for fraying and cracking on the top and the underside. You should also look for glazing.
  • Listen to the squealing when you start the car. Sounds originating from the front point to a faulty belt.
  • Automotive Education Procedures encourage consumers to apply soap to the drive belt pulley’s surface. This allows you to identify the faulty belt. If the noise reduces or stops after using the soap, you’ve located the bad belt.

Once you’ve determined that an alternator’s belt is genuinely responsible for the noise, you can take the following actions:

  • Replace a damaged belt. The specs of the new belt should match the attributes of the old belt. That includes the number of grooves.
  • Tighten a loose belt. This may involve replacing or tightening the pivot bolt. Laypeople should hire a mechanic to perform this task.
  • The same goes for aligning a misaligned belt. This is sensitive work. A mechanic can determine whether the misalignment is due to bent pulley flanges.
  • If the vehicle has automatic belt tensioners, check the pulleys and tensioner arm for defects. Replace defective tensioner bearings.
  • If coolant leaks onto the belt and sinks into the material, you’re better off replacing it. You can wash it off or apply products that specifically remove coolant. However, a new belt will give you peace of mind.

Bearing Noise: Whining, Humming, Or Growling Sounds

Moving parts require bearings because they reduce friction. A bad bearing does the opposite. It increases the friction, hence all the whining, humming, and growling sounds. Bearings can generate strange sounds because of the following:

  • If you routinely drive through high water levels, the water can strip the bearing of its lubricating grease.
  • Usually, alternator bearings will last 100,000 miles or more. However, you can destroy them by using insufficient lubricants or the wrong lubricants.
  • High temperatures can degrade the lubricant.
  • Contaminants such as dust and steel chips can interfere with the bearing’s work. Some lubricants are contaminated before you apply them.
  • Bearings can corrode because of poor lubrication and the presence of moisture, acid, and other contaminants. A corroded bearing will increase the friction instead of reducing it, producing loud noises.

How To Fix It?

Are you sure the bearings are at fault? Use this procedure to confirm your theory:

  • Open the hood and find the alternator.
  • Remove the belt and turn the alternator with your hand.
  • Do the bearings produce rough sounds when you turn the alternator? This points to bad bearings.
  • The second option involves getting a piece of tubing (roughly 12 inches) and placing it on the hose next to the alternator. The closer you get to the alternator, the louder the noise will become (if the bearings have failed).

Once you confirm that the bearings are at fault, you can apply one or more of the following solutions:

  • Lubricate the bearings. Look for a lubricant that matches the ambient temperature. For instance, you can apply frost-resistant grease to contend with winter conditions.
  • The experts at SLS Bearings encourage consumers to keep their work areas clean to prevent lubricant contamination.
  • Ask a mechanic to recommend additive chemicals that repel moisture or reduce its impact.
  • Replace corroded bearings.
  • Clean the rotor and slip rings. Replace them where necessary.
  • If the lubricant keeps degrading because of high temperatures, find and resolve the factors causing the high temperatures.
  • Keep bearings in a clean and dry location before installing them.
  • A mechanic may recommend a new alternator.

Electrical Noise: Buzzing or Crackling Sounds

People don’t associate alternators with buzzing and crackling sounds. Therefore, this noise should worry you because it points to a short. You should perform a comprehensive search that covers every element connected to the electrical system.

That includes the spark plugs, ignition coil, solenoid, etc. The fault probably lies with loose connections. The alternator uses cables to transmit electricity to the battery and the vehicle’s electronics. Damaged wiring can create electrical issues, such as arcing.

How To Fix It?

Electrical noise doesn’t have easy answers. You must inspect the vehicle’s electrical system until you locate the loose and worn-out wiring. Don’t assume that your alternator is to blame for these sounds until you examine the car.

This sort of comprehensive search requires a technician that can identify the cause of a short and replace defective components, including the wiring, fuse, solenoid, and alternator, to mention but a few.

Loose Or Misaligned Components And Their Impact On Alternator Noise

  • The alternator belt can become misaligned because of wear and tear. You will see splitting and cracking on the belt. Replace a damaged belt to stop the noise.
  • The belt is supposed to maintain a tight grip on the pulley. But the bent flanges on a pulley can misalign the belt. Tightening a loose belt won’t solve the problem if the pulley is damaged. In fact, the belt will remain loose. Don’t be surprised if it slips. You will hear a whining noise. You should replace a damaged pulley before attempting to realign or tighten a loose belt.
  • The alternator pulley can fall out of alignment with the drive system’s other pulleys, causing the belt to slip and increase friction. This leads to squealing and rattling. You can realign the pulleys.
  • The alternator has a spinning rotor shaft. That rotor can become misaligned after sustaining damage.

Impact Of Pulley Misalignment On Alternator Noise

The belt has grooves that align with the pulley’s design. This allows the belt to essentially drive the alternator. “J.E. Connell (The Gates Rubber Co.) and R.J. Meckstroth (Ford Motor Co.)” have a paper in which they insist that a drive belt cannot transmit power to automotive accessories without interacting correctly with the pulleys.

Therefore, you can’t afford to ignore misaligned pulleys. Misalignment can occur because of the following reasons:

  • You hired an incompetent mechanic to replace the drive system’s components. They installed the pulled at the wrong depth.
  • The mechanic installed the wrong pulley. It doesn’t match the alternator’s specs.
  • The crankshaft has too much endplay.
  • The bearings are worn out.
  • The belt is worn out.
  • The belt is loose.
  • The drive system is contaminated with oil, coolant, and other pollutants, accelerating the rate of wear and tear.

Misalignment increases the noise. Chirping and squealing tend to originate from defective or damaged belts. These sounds repeat. They may grow louder as the engine speed increases. Squealing may point to a slipping belt.

But you shouldn’t replace the pulleys and belts until you’ve performed a thorough inspection. For all you know, the belt merely lost its traction because it got wet, reducing the tension in the process.

Fixing misalignment issues will eliminate the noise, improve efficiency and extend the lifespan of the pulleys and belts.

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