Screeching Noise When Starting Car

How to Stop Your Car from Squealing on Start-Up

Turning on your car just to have it squeal loudly is as annoying as it is embarrassing. Everyone with in earshot will look around and want to know where such a distinct sound came from. Luckily, about 90% of the time there is a single, easily-fixable culprit.

Let’s take a look at…

Why does my car squeal when I start it?

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What Makes Your Vehicle Squeal when Starting

Most of the time, the squealing is do to something called a serpentine belt. When you open your hood, it’s the incredibly long belt that winds around multiple pulleys. It connects the crankshaft to other systems like the alternator, power steering, AC, and water pump. When it comes to your serpentine belt, there are three main reasons it could be squealing, all of which are easily fixed:

  1. Worn/damaged belt
  2. Loose tensioner
  3. Belt slippage

Worn Belt

Just like it sounds, this means the belt is old (roughly 100,000 miles or longer). This can range from the belt elongating, to worn edges, to worn-down teeth. It may also indicate that the belt is damaged. Either way, this requires the belt to be replaced. Serpentine belts aren’t particularly expensive, so don’t worry.

Loose Tensioner

The serpentine belt needs to be kept at a specific tightness and tension, which is the job of the aptly-named tensioner. On older vehicles, as materials and systems naturally degrade, the tensioner may not be able to stay at a specific setting. This can be fixed by readjusting the tensioner every once in a while (think of it like winding an old clock) or completely replacing the tensioner.

Belt Slippage

Do you park outside? Then you most likely have this problem. Cold and dew can affect the shape and grip of a serpentine belt. So if you start your vehicle and it squeals for a little while and then stops, this is your issue. This is more likely to occur in older belts, so replacing the belt is the easiest way to go about fixing it.

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Order a new serpentine belt through us. If you want to avoid the hassle of replacing it yourself, then have us install it for you.


2. Worn Pulley Bearings

If it’s not a problem with the drive belt, the pulley bearings may be at fault. Damaged or worn pulley bearings may cause a whining noise as the pulleys spin. In cases like these, it’s generally best to replace the pulley or pulleys entirely.

Why do these problems cause a screeching noise when driving, and is it always cause for concern?

Worn drive belts are a common source of screeching

Worn drive belts are a common source of screeching noises while driving

There are many parts on all vehicles that are considered normal wear items. The drive (“serpentine” or “V”) belt is one of these parts. The drive belt is made of a rubber compound and wears out over time. When the belt wears it can produce a squeaking or screeching noise. If the belt starts to make this noise, it should be brought in as soon as possible. If the belt is worn, that means it could break, and all vehicles will die shortly after the belt that drives the alternator breaks. Check out the sound a worn belt makes.

The alternator, idler pulley, power steering pump, and air conditioning compressor all have bearings that allow them to spin. Over time, the bearings will wear. As they wear they can make some very interesting noises. Sometimes they screech, sometimes they howl, and sometimes they gurgle. A noise from any of these bearings is an indication the bearing is failing. If the bearing fails, then that component (alternator, idler pulley, power steering pump, or air conditioning compressor) and likely the other components will stop working.

When brake components become worn, they can cause

When brake components become worn, they can cause a screeching noise

We talked about brake noise in the last post, but brakes can make different noises depending on what is worn. Some noise from the brakes is normal, especially after sitting for a few days or when sitting in the rain. Lack of use causes a thin film of rust to form on the face of the brake rotor. After two or three stops this film should be gone. If the noise doesn’t stop, there’s something else going on. Some cars have brake pad wear indicators that will screech when applying the brakes to warn that the brakes will need replacement soon. Another possibility is that the brake rotor has worn into a bowl shape. The brake pad can then sit inside the bowl and screech when the edges make contact. In this case the brakes continue to function normally, but the noise can be annoying. Fortunately this problem can often be remedied without replacing any of the brake parts.

A small hole in the intake system can cause a screeching noise when driving. Often this will trigger the check engine light. On some vehicles, especially Volkswagens and Volvos, when the positive crankcase ventilation valve fails it can cause a screeching noise. Sometimes described as a “whistle,” the noise can be so loud it can’t be drowned out by the radio. In either case there is a problem with the air intake system, which can cause poor engine performance and/or poor fuel efficiency.

As the engine spins, the camshafts and crankshafts ride on bearings. These are not ball bearings like you would usually think of a bearing, but a special material that forms the contact surface between the shafts and the channel. With regular oil changes, these bearings usually never need to be replaced. However, if the oil level gets too low or the engine has been put to extreme use, the bearings can wear out and cause a terrible screeching noise. If your engine makes this noise, then the engine is not long for this world and may give up the ghost when you least expect it.

4. Whistling

Your engine should not whistle while it works. In fact, a whistling sound that stems from under the hood typically indicates a vacuum leak is present in one of the hoses around the air intake system. These leaks are difficult to find but are easily repaired once identified.

3. Worn Drive Belt

The alternator is one of several accessories under the hood that are typically belt-driven on your car. These drive belts are built to last for tens of thousands of miles, but their rubber construction means they’ll grow brittle, stretch and crack over time. That means your drive belts may need to be replaced as they wear out and start to make noise. And if you have any oil leaks in the engine, the belts could become glazed with oil, causing them to slip and squeak. Luckily, installing a new belt is a fast and easy process for the pros in our service center at Carr Chevrolet.

Common Serpentine Belt Problems

Today’s cars have strong, durable serpentine belts, and they typically last between 60,000 and 100,000 miles with little required maintenance. Over time, wear and tear can take a toll on the belt and the pulleys, which often results in that high-pitched chirping sounds when you start the car and accelerate.

The most common serpentine belt problems include:

  • Worn/Cracked Serpentine Belt – Serpentine belts have grooves which fit into grooves in the pulleys. Over time, the friction wears down these grooves, resulting in a loose fit. A worn belt can, therefore, begin to slip, which is one of the causes the squeal. Alternatively, cracks can cause the belt to snap.
  • Failing Belt Pulleys – The belt is pulled along by several pulleys. A bad pulley can cause slippage or misalignment. Regular maintenance can detect pulley issues early.
  • Misaligned Belt / Improper Tension – A belt that’s too loose or too tight, or that’s fallen out of alignment, will cause the belt to slip.

Does the Noise Go Away After Warming Up? In cold weather climates, a serpentine belt may squeal on unusually cold days. This is because the belt is stiff and brittle. Often, though, the squealing stops after its had time to warm up. If you notice a squeal that dissipates after warming up and that’s not present on warmer days, the squeal might be weather-related.

2. Bad Bearing On An Engine Accessory Pulley

While the reasons so far are usually intermittent and associated with specific aspects of driving, this is a squeal you’re more likely to hear when the engine is running. Most modern cars are equipped with a serpentine belt that’s routed around a variety of pulleys, at least one tensioner, and likely an idler pulley or two. This belt turns the pulleys of important accessories like the AC compressor, power steering pump, the engine’s water pump, and others. All the pulleys in this system have bearings that can go bad after many miles. When these bearings go bad, it’s common for them to squeal whenever the engine is running.

9. Clunking

This sound could be caused by several different things depending on where the noise is coming from. If the clunking occurs while braking, it could mean that your brakes are severely worn. An inspection from a technician will confirm whether the rotors, calipers, or pads require replacement to resolve the sound. If the clunk occurs while going over bumps, it may be due to poor suspension. If the clunking happens while going around corners, this could indicate a problem with the steering system, tires, or a faulty wheel bearing.

Do your knees pop when you walk? Do you make a groaning sound when you get up? Similar to humans, as cars age, they start to make noises. While somewhat inconvenient, these noises are the ideal way for your car to communicate that a certain area needs attention. Minor repairs, maintenance, or major repairs may be required depending on where the sound is coming from, how long it’s been making noise, and the age or mileage of the vehicle.

If your car is making a clunking, groaning, whistling, or squeaking noise when driving, our ASE-certified technicians are here to help. They’ll lend an ear and perform diagnostics to determine the cause of your vehicle’s unlikeable soundtrack and repair the issue. Then the only sound you’ll hear while you drive is the wind whipping through your hair as your favorite song plays on the radio.

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