Alternator belt replacement and symptoms of belt looseness or broken

What is an alternator belt?

The car alternator is essentially a power generator which keeps the car battery charged and allows it to continuously power the key electrical components of the car. Without this, the battery would be drained quickly as it does not have the power to supply electricity to all of the components for extended periods. The alternator is attached to the engine by brackets and bolts. It is powered by the crankshaft mechanism and driven by a belt.

In the past, car engines used several separate belts, such as V-belts, for various engine units. The alternator was driven by a separate drive belt, which wrapped around the crankshaft and alternator pulleys. Nowadays, the large majority of vehicles use one belt, known as a serpentine belt, to drive multiple units, including the alternator, power steering pump, water pump, air conditioning system unit. These ribbed belts are designed to maintain as much contact with the pulleys as possible to increase the power transmitted. If the belt gets damaged, these units will stop working and, as a result, the car’s power system could shut down.

When to replace the belt

V-belts typically last up to 4 years or 40,000 miles, however, new serpentine belts can last much longer and are generally easier to maintain. The average serpentine belt can last for anything between 60,000 to 100,000 miles. Belts made from ethylene propylene diene monomer (EPDM) are more durable than standard ones and can be used for around 10 years before they need to be replaced.

However, several problems can emerge as the alternator belt ages. For example, it can start to fray, wear, crack, or peel, as well as become loose or misaligned. Replacing the belt in good time is the best way to prevent the system from shutting down while the car is on the road and severe damage to the driven components and car battery.

Causes of alternator belt problems

Symptoms of a loose alternator belt

Here is a list of the most common symptoms to help you identify when your belt needs to be replaced due to a loss of contact or tightness.

Can I replace the alternator/serpentine belt myself?

Of course you can. As long as you have the right tools and skills, you should be able to replace this component yourself at home. However, you will also need to replace the other broken or worn parts, such as the belt tensioner.