Do I Really Need to Replace Cracked Belts on My Vehicle?

Quick facts

  • Approximately 19% of vehicles on US roads have a worn belt that needs replacement.
  • Belt failure risk rises sharply after four years of operation.
  • Three or more cracks in a three-inch belt section is a replacement threshold.
  • A failed serpentine belt disables the alternator, power steering, and water pump simultaneously.

Many of the key components and systems of your vehicle are run or powered via a rubber belt that connects to the engine's drive shaft. With the aid of pulleys, these belts drive the engine fan, water pump, air-conditioning compressor, power-steering system, and the alternator in most vehicles. The alternator is a very important component that provides electrical power and charges the battery while the engine is running.

There are V-belts and/or Serpentine belts that will run one or multiple systems in your vehicle. Once an engine is running the belt operates continuously. High under hood temperatures plus the constant flexing that belts do, ultimately wears out the belt. Eventually, even the best belt will break. When it does the systems and/or accessories that the belt runs will stop operating.

According to the National Car Care Council, 19% of the cars on the road today have a worn belt that should be replaced. That equates to almost to 1 in every 5 cars. According to research statistics the incidence of belt failure rises sharply after four years of operation in many vehicles.

An Automatic Belt Tensioner is a metal device with a pulley that attaches to the engine. It applies tensions to the belt by way of an internal spring device that comes into contact with the belt. For a belt to function properly, it needs to operate with tension. Proper tension keeps the belt in contact with the various components with just enough pressure so that it provides power and does not slip in the accessory's pulley grooves yet not so much that the tension creates heat which can shorten the belt's life.

Belts, pulleys and tensioners should be inspected on a regular basis, with each oil change performed on the vehicle. Some of the symptoms to look and listen for are:

  • Belt Cracking – 3 or more cracks in a 3" section means it is time to replace it.
  • Belt Squeaking or Squealing – could be a belt, pulley or tensioner wearing.
  • Rust Bleed around a pulley or tensioner – recommend replacement it is wearing out.
  • Oscillation or excessive movement of belt – tensioner is not holding proper tension and needs replacement.

Replacing a belt, pulley or tensioner is a relatively simple or minor repair. But a failure can result in other damage at times and a breakdown can occur costing more time and money. To keep your vehicle in proper working order don't be the 1 in 5 cars on the road with belts that need replaced, have them replaced when they show signs of wearing to reduce your chances of an unexpected occurrence.

Frequently asked questions

Common questions

What is the difference between a serpentine belt and a V-belt?

A serpentine belt is a single continuous belt that snakes around multiple pulleys to drive all engine accessories, the alternator, power steering pump, water pump, and air conditioning compressor, at once. A V-belt is a narrower belt that typically drives only one or two accessories. Most vehicles built after the late 1980s use a single serpentine belt with an automatic tensioner. Because a serpentine belt handles everything at once, its failure is more immediately disabling than a single V-belt failure.

How does an automatic belt tensioner work and what happens when it fails?

The automatic belt tensioner uses an internal spring mechanism to apply consistent pressure against the belt, compensating for belt stretch over time. When the tensioner weakens, the belt can slip on pulleys during high-load moments, such as when the A/C compressor engages, causing a brief squeal. A failed tensioner may also allow the belt to wobble visibly on the pulleys. Replacing the tensioner at the same time as the belt is standard practice because a new belt on a worn tensioner will not last as long.

Can I drive without power steering if a belt breaks?

On vehicles with hydraulic power steering, a broken serpentine belt immediately disables the power steering pump. The steering will still function, it is mechanically connected, but the effort required increases dramatically. At parking lot speeds this can be very difficult to manage, especially for smaller vehicles or those with wide tires. At highway speeds the effort is manageable but unexpected. Electric power steering, which is becoming more common, is not affected by belt failure because it is driven by the car's electrical system, not a belt-driven pump.

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