Troubleshooting Common Problems With Generators and Alternators

If you own a vehicle, it is highly likely that you will eventually have to replace the alternator in it.

This is not as simple as replacing the battery. The alternator is under a lot of stress all the time and has to withstand a lot before it buckles under the pressure. How often your alternator needs to be replaced will depend on the model of your vehicle and how old it is. You may find that it is easy to tell when the alternator needs to be replaced.



The first sign that your Alternator needs to be replaced is a slow start or lack of power. The alternator makes up about forty percent of your engine’s power. The alternator uses a pulley system to control the rotation of the shaft that is in turn controlled by the starter. They generally last a long time, however some cars require new ones as soon as 50,000 miles, others only need to be replaced after sixty,000 miles. If you start to experience a slow start or if there is a delay in the starting process then you most likely have a failing starter.


Another indicator of a failing starter is if you see a low voltage in the battery warning light.

The voltage is usually measured in volts, however the lower the number means that the alternator is also suffering from a low battery. Low voltage also indicates that the starter is not being properly maintained. If there is excessive wear and tear signs in the flywheel or belt then you may want to consider changing your alternators. Another sign of a failing starter is a burned-out battery warning light.


A third indicator that you should watch for before having an alternator replacement is if you hear a clicking sound when you start the vehicle.

Generally there will be a small noise when the vehicle starts, however if there is a popping sound it could mean that the old belt is coming loose. If your vehicle starts with a cranking noise but then goes silent when you start it then you most likely have a high wear belt. Another indicator that you should watch for is if you hear a whining noise when the vehicle starts or when the vehicle slows down. This is caused by a serpentine belt.


There are two types of alternators.

There are the good alternator and the bad alternator. The bad alternator is often referred to as a “start-up” alternator, because when the vehicle is started with the start-up noise can be associated with it. On the other hand the good alternator is known as an “idling” alternator, and when the vehicle is idling it is the belt attempting to parallelize the speed of the rotation of the crankshaft.


Another indication that you should watch for is fluid leaks around the alternator.

If the alternator begins to vibrate or feel hot then you should most likely have fluid leaks in the alternator bearings. Sometimes when the timing belt loosens up the timing belt can leak, which will cause the timing to become off slightly. This slight error can result in the engine being put out of torque with low power. The best way to prevent this from happening is to always purchase new timing belts, and make sure that the alternator is properly maintained.


A test that can be performed on the dashboard can tell you if the vehicle needs an auto repair technician to look at the vehicle.

The dash may appear clean but behind the dash you can see the engine compartment. If the vehicle continues to function without any noticeable changes then the dashboard is probably okay, however if the vehicle starts to smoke then you should consider having a technician look at the vehicle. The diagnostic trouble shooting guide can usually be obtained at the auto parts store where the vehicle was purchased.


The diagnostic trouble shooting guide will give you a list of things that you should do before calling the technician.

One of the first steps to repairing the vehicle is to check the battery for any signs of a dead battery light. You can use a digital battery detector to check the battery if it turns on and flickers. If the vehicle still has the dead battery light on then the alternator may need to be replaced.

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