How to Replace Your Serpentine Belt

The serpentine belt transfers power to your vehicle's many components. Replacing a worn or cracked belt can make your engine run more smoothly and save you from potentially costly repairs.

How to Replace Your Serpentine Belt

Worn serpentine belt

Signs to Look For

Serpentine belts don't need to be replaced particularly often. Most last for around 50,000 to 100,00 miles. Consult your owner’s manual maintenance section for replacement intervals. When you notice one of these four signs, it's time for a new serpentine belt: Serpentine belt transfer power from the engine’s crank shaft to the engines alternator, power steering pump, smog pump*, and air conditioner compressor. This one belt provides power to all the vehicles components. Some vehicles have a dedicated belt for the alternator just in case the serpentine belt should break. The vehicle can continue driving until it reaches a safe place to stop. *if equipped.

• Lack of power steering or air conditioning: The serpentine belt controls peripherals such as power steering and air conditioning, so a breakdown of one or both may signal that you need a replacement.
• Wear and tear: If a visual inspection of the serpentine belt reveals significant wear and tear, including cracks, separation, or damage, it's time for a new belt.
• Squealing noise under the hood: This may signal that the belt is slipping. Sometimes a new belt is not needed. The belt is kept tight through the belt tensioner. The tensioner is a self-adjusting pulley that maintains pressure on the belt to reduce slipping. At times, the bearings in the tensioner pulley become worn. This causes the squealing noise. Check these bearings when performing a belt change.


Note the placement of belt

Serpentine belts have that name for a reason. They snake in and out of a series of pulleys and peripherals, and the path they weave through is unique to your model vehicle. To preserve the belt's position, take a few snapshots from different angles or sketch the way it winds through the engine. If the belt is already out of place, locate the driver's manual or the under-the-hood placard, where you'll find a sketch of the routing.


Loosen and unthread the belt

Before removing the belt, you'll need to release the tensioner, which automatically keeps the belt taut while you're driving. Use a ratchet that fits into the bolt and release the tensioner. Then unthread the belt carefully, taking care not to disturb or damage the network of pulleys and peripherals.


Check for damage

After removing the belt, inspect it for signs of damage. Many belts wear out over time, but some wear down due to misalignment or other issues. Misalignment won't resolve itself when you replace the belt, so determine whether this is a problem. Look for disintegration along the edges and separated ribs, both of which are signs that you have misalignment on your hands. Use a straightedge to make sure the pulleys are aligned correctly, and then remove any old dirt and grime from the pulleys. This is a good time to look for oil leaks, too. Oil can increase wear on serpentine belts.


Install the new belt

Replacing the serpentine belt is as simple as threading it into position and releasing the tensioner. Belt tensioners are mostly spring tension. Once installed, the spring retains pressure to the belt. Use a torque wrench to give the tensioner the right level of tightness, and then let the engine idle for at least 60 seconds as you make sure the serpentine belt is working correctly. Replace any other parts or coverings you've removed before taking your vehicle for a spin. A serpentine belt replacement is an essential part of routine auto maintenance, but it doesn't have to be difficult. Get the parts you need from AutoZone.

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Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

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