Alternator Pulley Buyer’s Guide
- An alternator pulley allows a vehicle’s alternator to be driven by a V-type or serpentine drive belt, which is crucial in turning mechanical energy into electricity.
- Depending on several factors, this part can last up to 40,000 or 60,000 miles.
- There are three different types of alternator pulleys in the market today: the solid pulley, the overrunning alternator pulley (OAP), and the overrunning alternator decoupler (OAD).
- The most common signs of pulley problems include intermittent battery warning light, activated check engine light, weird noises coming from the alternator, and excessive belt tensioner movement.
- An aftermarket alternator pulley is usually priced anywhere between $17 and $130.
If your vehicle relies solely on the car battery to power several electrical components, it won’t take long before the battery is fully drained. This is the reason why vehicles are equipped with a charging system that can supply electricity to the car battery. In the center of this charging system is the alternator.
The alternator is the device that turns mechanical energy into electrical energy for your vehicle. Without it, there won’t be enough electricity for your vehicle’s headlights, entertainment system, air conditioning system, and more. For it to function properly, it needs the help of the alternator pulley.
What Is an Alternator Pulley?
An alternator pulley allows your vehicle’s alternator to be driven by a single V-type belt or a single serpentine drive belt. By doing this, the alternator gets the current it needs to replenish the charge of the battery and supply the electrical system with enough electrical power.
An alternator pulley may also be used as a cooling fan for the alternator. It helps lower the heat in the interior wire, bearings, and brushes. You can find this device connected to the alternator's main shaft using a nut and washer.
How Long Does an Alternator Pulley Last?
An alternator pulley can typically last from 40,000 up to 60,000 miles. However, several factors can speed up the deterioration of this component. Friction and high temperatures, for example, can cause the alternator pulley to wear out prematurely. When this part starts to show signs of failure, it’s best to make the necessary replacement as soon as possible.
Types of Alternator Pulleys
Most modern vehicles use special pulleys that are engineered to reduce noise and vibration. These pulleys are also capable of extending the service life of the alternator. Here are the different types of alternator pulleys available on the market today.
This is the standard alternator clutch pulley, which is commonly found in older vehicle models. It has no other function except to drive the alternator so that the charging system can recharge the battery and supply electricity to your vehicle’s electrical devices.
Overrunning Alternator Pulley (OAP)
An alternator overrunning clutch pulley features a one-way clutch mechanism inside the hub. This allows the pulley to rotate freely in the overrun direction and to lock up when it is rotated in the opposite or drive direction.
This mechanism allows the alternator to free-wheel spin when the engine suddenly loses speed. It also helps eliminate belt chirp noises during engine shutdown and transmission shifting.
Overrunning Alternator Decoupler (OAD)
Similar to an OAP, an overrunning alternator decoupler has a one-way overrunning clutch inside the hub to get rid of belt chirp noises. It also features a steel torsion spring that helps absorb engine vibration caused by the firing of the combustion cylinders. The spring also cushions the vibration from the lower idle speeds of modern engines.
Signs That You Need an Alternator Pulley Replacement
The alternator won’t function well without a functioning alternator pulley. To avoid loss of power in your vehicle’s electrical system, watch out for the following signs of failure:
Belt Tensioner Moves Excessively
If you want to quickly check if your alternator pulley is still in good shape, you can leave your engine running at idle and inspect the belt tensioner. The belt tensioner shouldn’t move excessively. If it does, it is a sign that the alternator pulley is already worn out.
Loss of Power Steering
The sudden loss of your vehicle’s power steering is one of the signs of a faulty alternator pulley. As soon as you notice this issue while driving, head straight to the nearest auto repair shop or safely pull over and call a tow truck to prevent causing a serious road accident.
Intermittent Battery Warning Light
Another sign that you have a bad alternator pulley is an illuminated battery warning light. This may be activated due to an alternator that has failed to recharge the battery.
Your vehicle may still run fine. However, once the battery runs out of juice, you will encounter problems right away. The engine may stall because there is no electricity to start the combustion process.
Odd Alternator Pulley Noises
A worn-out pulley may produce a loud squeaking noise when starting the engine, an odd clunking sound while you are driving, and a subtle squeal while the engine is at idle.
Activated Check Engine Light
Different engine problems can cause a vehicle’s primary computer to activate the check engine light. A faulty alternator pulley is one of them. Before purchasing a replacement, you must first confirm that this part is the real culprit.
Connect a scan tool to your vehicle’s OBD port or have a mechanic do it for you to retrieve the specific error logged by on-board diagnostics.
How Much Is an Aftermarket Alternator Pulley?
The price range of an aftermarket alternator pulley usually falls anywhere between $17 and $130.
To speed up your search for the right components at CarParts.com, use our website’s vehicle selector. Just need to enter your vehicle’s year, make, and model to narrow down the search results to only compatible parts.
Replacing Your Alternator Pulley: A Quick, Jolt-Free Guide
Your alternator produces electricity for your vehicle—power that you need for everything from turning on your dome lights to starting your car. Your alternator does this by using a rotating pulley, which is driven by either a single belt, or a serpentine belt. This pulley can rotate at speeds up to 18,000 revolutions per minute. As with anything that moves repeatedly at high speeds, your alternator pulley can get worn out in time. When that happens, you should replace it right away. With the some basic tools and one special tool, you can save some cash in repairs by doing it yourself.
Difficulty Level: Moderate
Here's what you'll need:
- Alternator pulley puller
- Socket wrench set (must include a 3/8-inch ratchet)
- Pry bar
- Replacement alternator pulley
- Vehicle owner manual
And here are the steps:
- Open the hood of your vehicle and use your wrench to disconnect the negative battery cable from the battery terminal.
- Use the appropriate wrench to loosen belt tension bolt on your alternator.
- Push the alternator assembly with the pry bar so that the belt becomes loose enough to slip over the pulley and remove.
- You should find four pulley attachment bolts—remove them with your 3/8-inch ratchet.
- Take your alternator pulley puller. You will find four holes at the of each of its legs. Line those up with the bolt holes on the pulley. Screw them in by hand until they are tight enough.
- Use your ratchet and a socket to tighten the pulley bolts.
- Turn the shaft knob on your alternator pulley puller. Keep turning until the alternator pulley slides out from the shaft.
- Install your replacement alternator pulley by following the reverse order of disassembly.
Remember not to lose any components (nuts, bolts, etc.) in the process of removing the old alternator pulley. You will need those same components in installing your replacement pulley in exactly the same way as the old one. Make sure you don't over-tighten the pulley bolts as this will damage the threads. Refer to your vehicle owner manual for specifications (such as the location of your alternator and the kind of mounting bolts needed) that may require you to deviate from these general instructions.