(Updated on May 26, 2020)
Anyone who drives a car has probably heard of an alternator before. It is responsible for sustaining the charge of the battery so that it can power the electrical components of the vehicle.
If an alternator did not exist in the vehicle, the battery would never be able to power all these electronic components for more than a short period. It simply does not generate enough energy to do this.
The alternator keeps the charge going in the battery so that the power can continue to cycle throughout the vehicle.
When an alternator is actively charging the battery, it is actually spinning inside the vehicle. There is something called an alternator belt (also called a serpentine belt) which wraps around a pulley or multiple pullies that is connected to the alternator.
The other end of the pulley wraps around the crankshaft. Therefore, the crankshaft and alternator are able to rotate together by the alternator pulley. If you didn’t have this pulley, then the alternator would not be able to do its job.
Related: Symptoms of a Broken Alternator Belt
Loose Alternator Belt Symptoms
As you continue to drive your vehicle, the alternator belt gets a little bit more worn each day. It could be susceptible to wear and tear damage or it may even come loose from the pulley. Once that happens, you can expect all kinds of symptoms to arise.
If you notice any of these symptoms, the best thing to do is have your alternator belt replaced immediately. Otherwise, you could find yourself stranded somewhere after your vehicle’s electricity shuts down.
Here are the five most common symptoms of a loose alternator belt.
1) Flickering/Dimming Lights
If you are driving your vehicle and suddenly notice the headlights flickering or dimming or cabin lights inside the vehicle dimming, this could mean you either have a battery or alternator issue.
When it’s a problem with the alternator belt, the flickering or dimming lights may stay consistent for quite some time before they completely go out since no power is getting to them. Depending on how old the alternator is, it can also be a sign the alternator itself is on its way out.
2) Vehicle Stalls
If your alternator belt gets too loose as you’re driving, it may cause your engine to stall. This means that you’re engine essentially shuts down and you’ll be forced to pull over onto the side of the road.
Obviously, you wouldn’t want this happening on a busy street or rush hour traffic on the highway. If this symptom is consistent with the flickering lights issue, then a loose alternator belt is more likely the cause.
3) Battery Warning Light
One of the first symptoms that you should notice is the battery warning light coming on. This warning light does not always mean there is a problem with the battery itself. It could just mean there is an electrical problem in the vehicle which is impacting the battery.
Rather than wait to see what happens, you should get it checked out by a mechanic or if you’re confident, take it home and troubleshoot the issue. A loose alternator belt may be the culprit.
Related: Causes of an Alternator Going Bad
4) Chirping or Squealing Noise
If the serpentine belt is loose, it often results in various noises coming from your engine. With a loose belt, it doesn’t sit right up against any pullies that are rotating it so noise may occur from the friction.
You’ll often hear cars driving down the street that have this problem and it seems to occur more in colder weather. If you fail to replace your alternator/serpentine belt, the problem will only get worse and to the point that the belt may completely slip off a pulley or pieces of it start breaking off.
5) Dead Battery
When the alternator can no longer fully charge the battery because of a loose alternator belt, the battery will then try to provide all the power to the vehicle on its own. Unfortunately, the battery will die within minutes because it doesn’t have enough power to sustain all the vehicle’s energy needs by itself.
Alternator Belt Replacement Cost
The replacement cost of an alternator belt is typically between $100 and $200. The part cost is between $25 and $80 while the labor cost is between $75 and $120. The true replacement cost will depend on how long it takes the mechanic to access your alternator belt.
Related: Average Alternator Replacement Cost
Sometimes it is easy to access, so the labor will only take one hour or so. But if the belt is difficult to access, you could be looking at multiple hours of labor charges. At the most, it should not go over $300.