Alternator Belt –Explained

Alternator Belts alternator helps power all of a car’s electrical systems, including the starter motor, speaker system, and lights. A bad or failing alternator can discharge your battery, cause issues with your car’s electrical systems, or leave you stranded when you need to use your vehicle. It’s a good idea to know a few simple tests and early signs of alternator failure to avoid a breakdown. Here ‘a a step-by-step process to test your car’s alternator.

If you’ve ever owned a car past the 50,000-mile mark, you’ve heard a mechanic talk to you about the drive belts on your vehicle. You may have nodded as they explained the condition of those belts and their recommendation to maintain them. But you also may have wondered- What exactly do those belts even do? Knowledge is power when it comes to keeping your car, and Christian Brothers Automotive Round Rock is here to help you grasp why those belts are so crucial to the function of your vehicle.

alternator belt

Why Are Your Car’s Alternator Belts So Important?

When talking about car maintenance, you need to be familiar with two belts — the serpentine belt and the timing belt. The serpentine belt winds through your engine and carries power to several key components, including the alternator, air conditioning, and power steering pump. The serpentine belt connects to the water pump in some cars.

Meanwhile, the timing belt synchronizes the actions of your camshaft and crankshaft. That means that it keeps all your engine valves working harmoniously and ensures that your engine functions as intended. Maintaining the serpentine belts and fan belts in your car is vitally important to the overall health of your vehicle. Should any of these belts fail, it could damage your engine, alternator, and power steering pump. In other words, failure to have your belts replaced on time could result in much more demanding and expensive repair needs.

When to Replace Your Alternator Belts

As for when you need to replace these belts, there’s no hard-and-fast rule. It varies depending on the vehicle and the conditions under which you drive. As a rule of thumb, the timing belt in a newer car will usually last 100,000 miles or so, and the serpentine belt will last around 90,000 to 100,000. However, it’s good to have your engine inspected regularly and follow your technician’s advice about when to have those belts replaced.

  • You can also be alert to some common red flags for belt failure. Some of these include:
  • Squealing noises from the front of your vehicle
  • Loss of your AC or power steering
  • Engine overheating
  • Visible cracks/wear on your belts

alternator belt

Symptoms of a Loose Alternator Belt

The most common symptom of a loose alternator belt is a battery warning light on your dashboard. You can also often hear a squeaking belt when the engine is cold. If your headlights are flickering or the steering is heavy, they can also be caused by a loose belt.

The alternator belt powers the alternator and many other parts in the engine bay. Therefore, also a lot of things can fail when it becomes loose.

Loose or Bad Alternator Belt Symptoms

When buying a new belt, you have to make sure and compare it with the old belt to make sure you got the same length, as many car models can have many different belt lengths depending on the utilities like power steering, air condition, etc.

When tightening the new alternator belt, you have to make sure not to pull it too tight. This will cause a much shorter lifespan, and it can even damage the bearings in the parts like the alternator or power steering pump. Most newer car models also use an automatic belt tensioner, so it is uncommon that the belt will become loose. However, it can happen, and if you have a loose belt on a car with an automatic belt tensioner, you have to make sure the replace the tensioner while you replace the alternator belt.

Here is a more Detailed List of the Most Common symptoms of a Loose or Bad Alternator Belt:

Battery / Alternator Warning Light

As the alternator or serpentine belt is powering the alternator, it will cause the alternator to struggle when the belt is loose. There is a battery warning light on your dashboard in most car models, which will light up when there is a problem with the charging system. When the alternator belt is loose, the alternator will not spin at its optimal speed, which can cause the charging voltage to drop so that the warning light will pop up.

alternator belts

Squealing noise when cold

you have probably heard that many older car models have a high pitch noise when starting them hard, which will slowly fade away as the engine becomes warmer. This is mainly due to a loose alternator belt, which will become more slippery and wet when it is cold and create a high pitch noise when it slips on the alternator.

If you have a high pitch noise when you start the car for a few seconds, it is time to check the alternator belt. You can also experience a constant high pitch noise if the belt is always loose.

Heavy or Jiggery Steering

The alternator or serpentine belt powers the alternator and the power steering pump. Some car models have a separate belt for the alternator and the power steering pump but mostly use the same. This means that when the alternator belt can also cause the power steering pump not to function correctly, you will recognize this as a jigger or constant heavy steering

Dead Battery for Alternator Belts

The alternator belt is loose; it can charge the car battery but is not good enough. This is most noticeable when you are trying to start the car. If it sounds exhausted on the starter, it can signify a loose alternator belt. If it gets bad enough, it can even cause the car battery to be completely dead the next time you are trying to start your car.

Alternator Belts Location

Finding the alternator belt is relatively easy in most car models, though. Look for a strap going around different wheels, and you will most likely find it. In some car models, the belt can be located quite low down in the engine bay and close to the car’s body, making it difficult to see from above. In this case, you may have to lift the vehicle and check from underneath.

alternator beltAlternator Belts Replacement Cost

The average alternator belt replacement cost is $50 to $300, depending on the car model. An alternator belt costs $20-$100, and labour costs $30-$200 to replace it. The alternator can be installed very closely on the car’s body, making it difficult to reach it. In some car models, you even have to lift or lower the engine to get it correctly.

As I discussed before, most modern car models use an automatic belt tensioner. And if you have a loose belt on one of these car models, you have to replace the tensioner. These tensioners are often slightly pricier, and you can expect to pay $30 – $150 for a new one. The alternator belt is often relatively cheap, so you can save some money if you know to replace and tighten it yourself.


Now that you’ve checked your car’s alternator, it’s time to finish up. Further testing is needed if your tests result in regular voltage readings. But you still have issues with battery warning lights, a discharging battery, or your car’s electrical systems. You may want to enlist the help of a professional mechanic who can test or replace the alternator for you.

Your Mechanic offers car repair and maintenance services at the convenience of your home or office. Seven days a week saves you up to 30%. This article originally appeared on How to Test Your Alternator.

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