Serpentine Belt
What it is
The serpentine belt is a single long belt that winds around several pulleys to drive accessories like the alternator, power steering, water pump and A/C compressor.
What it does
It transfers engine power to the accessories. A worn, cracked or snapped belt causes squealing, loss of power steering and charging, overheating (if it drives the water pump), and a snapped belt can strand the car.
Symptoms of failure
- Squealing or chirping, especially on start-up or in the wet
- Cracks, glazing or missing chunks on the belt
- Battery light or loss of power steering
- Overheating (on engines where it drives the water pump)
- A sudden total accessory loss if it snaps
Which vehicles need it
Most modern engines use one serpentine belt. The tensioner and idler pulleys wear alongside it.
Replacement cost
| DIY (part only) | $20–$70 |
|---|---|
| At a shop (parts + labor) | $100–$250 |
| Replacement interval | Typically every 60,000–100,000 miles (100,000–160,000 km); inspect at services. |
| DIY difficulty | Easy–Moderate (DIY) — release the tensioner and route the new belt; note the routing first |
| Recommended brands | Gates, Continental, Dayco, ACDelco |
Where to buy the part
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Frequently asked questions
What happens if my serpentine belt breaks?
You lose everything it drives at once — charging, power steering, and often the water pump, so the engine can overheat. Do not keep driving on a snapped belt; have it replaced before it fails if it is cracked or squealing.
Why is my serpentine belt squealing?
Usually a glazed or worn belt, or a weak tensioner letting it slip — often loudest on cold or wet start-up. Replace the belt (and check the tensioner) to cure it.