The Serpentine Belt: A Small Belt with a Huge Impact

What is a serpentine belt?

The serpentine belt is a triumph of efficiency. Rather than the older multiple belt system in which individual belts were used to run engine accessories off of the crankshaft, the serpentine belt does multiple jobs all by itself. Not only does this save engine space, it makes repair and replacement of the belt itself far easier. You don’t have to remove three belts to replace one.


As well as being one of the most easily accessible engine parts to view and replace, the serpentine belt is polite enough to announce when it needs to be replaced- it will squeal, and it will squeal very loudly. This noise is an indication that the serpentine belt is either falling out of alignment due to misaligned pulleys, has a seized tensioner or that the belt itself is decayed and needs repair. No matter what the issue with the serpentine belt, it will almost always squeal before it breaks. After that occurs, the belt will have to be replaced before a vehicle can go anywhere.

Changing a Serpentine Belt

Before attempting to replace anything yourself, give the serpentine belt a visual examination. Is it cracked or fraying? Are bits of it missing? Does it look dark and oily? If the squealing is due to the tensioner coming loose and the belt falling out of alignment, then replacing the belt onto the proper track and tightening the tensioner with a ratchet will handle the problem.

If the belt is showing obvious signs of wear, a replacement before it snaps is better for you and your engine.

  • Examine the path the serpentine belt takes. This item runs multiple accessories, so it’s going to have a looping route over the pulleys. If the belt has already broken, consult the owner’s manual or check under the hood for the belt routing placard that shows how the belt should appear on the pulleys.
  • With the belt’s proper placement sketched or firmly in mind, use a ratchet to release the tensioner- there’s usually a hole provided in the tensioner’s arm for this purpose- and remove the damaged belt.
  • A quick examination of the belt can tell you if the damage is merely normal wear and tear or if there are problems with the pulleys themselves. Any cracks are usual for a belt that’s at the end of its life span. If the edges of the belt are disintegrating, bits of rib are tufted out or bits of fiberglass are fraying, you could have a problem with the pulleys, idlers or tensioners. If this is the case, put the new serpentine belt on, keep the old and take it in for attention as soon as possible.
  • Regardless of what the issue is, the belt will need to be replaced before the car goes anywhere. Following your belt route, thread the new serpentine belt into place. Note: Use one hand to thread the belt around the last pulley while keeping the tensioner slack with the other hand.
  • After the belt is in place and everything has been tightened, start the engine and let it idle for a moment. Check the hash mark on the tensioner to ensure it falls between the marks on the arm that indicate high and low pressure. The hash mark should stay between the tension indicators if the belt was installed properly.

Serpentine belt replacement can be accomplished with just a few hand tools and someone’s assistance for safety, but professional tools make the replacement of a serpentine belt much easier. By taking your car in to Quanz to have the serpentine belt replaced, you also have the opportunity to get professional advice on the spot if there should be a problem with the pulley system itself or anything else under your hood.