Part Profile: Alternator

diagram of an alternator

This is the second in our series covering basic vehicle components. The more you know about your ride the easier the conversation with the mechanic and the more likely you are to not need to see your mechanic! Let me know what you’d like to see next! Sorry for the long delay since the CV joint article! As we are about to get into, the alternator is responsible for the electrical function of the vehicle and a big rig has big electrical needs.

water cooled alternator at colorado auto parts storeThe alternator is responsible for charging the battery and power the electrical systems of your vehicle. Your car uses quite a lot of electricity to start an engine and run all the electrical components. Without the alternator, your car’s battery simply won’t charge and nothing in your vehicle receives any power. Therefore, the alternator is a pivotal but often overlooked part of a vehicle. 

The alternator is most often found near the front of an engine and is driven by the crankshaft which converts up and down motion of pistons into circular motion. It’s mounted on the engine using brackets and bolts. Some cars use a separate belt to drive the alternator through crankshaft pulley while others have a serpentine belt which gets power from the crankshaft pulley and drive all the components that need power.

The alternator simply converts the mechanical energy of an engine into electrical energy to power electrical accessories of the car. It does so through its three major components: rotor, stator and diode. Electricity is basically produced through the stator-rotor relation. When the crankshaft pulley turns the alternator pulley, the rotor which is essentially a magnet spins inside the winding of copper wires (stator). This spinning magnet inside the stator coils generates electricity. Then comes a diode in the play whose job is to convert the AC electricity into DC which your car can use.

Signs of Alternator Problems

While an alternator is a relatively simple component, it has a critical role in any car’s operation. When your car’s alternator is going bad, you’ll notice few warning signs.

Warning Light

Many cars display a warning light on the instrument panel when the alternator is struggling. It is usually shaped like a battery. This alerts you that an alternator is not generating enough charge to keep the system up and needs attention.

Reduced Electrical Capacity

Because the alternator is a crucial component of vehicle’s electrical system, any issue with it will have an effect on the functioning of electronic accessories. A dying alternator can often cause your car’s headlights or dashboard lights to dim or it may cause other accessories such as power windows, seats or sound system to operate slower than usual. Any warning like this is a clear indication of malfunctioning alternator.

Odd Smells and Sounds

As the alternator pulley is driven by a crankshaft pulley and spins about two to three times faster, any misalignment in the pulley will cause strange smells or noises. A grinding or whining noise is also produced if the supporting bearings or bushings are worn out. A belt that is not turning freely will generate more friction and heat and then create the smell of burning rubber. Or if you notice a smell similar to that of electrical fire, this could be an indication of loose belt slipping on the pulley, thereby overheating the alternator and causing poor output. Tightening the belt might solve the issue.

Keep doing a visual inspection of the engine compartment on a regular basis so that you can detect a loose, tight, cracked or worn out belts and avoid any major problems.

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Part Profile: CV Joint

cv joint sketch

This is the first of our part profile series. The idea is to give everyday drivers more information on important parts of their vehicles. You can understand your entire vehicle, one part at a time.

The constant velocity joint or CV joint provides a form of mechanical coupling in which the rotational speed of input and output shaft remains the same no matter what the operating angle of the joint.

The CV joint is located at the axel and allows the job shafit to accomplish it’s two most important jobs. That is, transmit power to the wheels and adjust to the suspension. As the suspension of the vehicle changes due to road conditions, the CV joint allows continued transfer of power. This gets even more complicated in the case of front wheel drive vehicles where articulation angles are higher because of steerable wheels. With the wide range of variable angles by suspension travel and wheel steering, the axle has to act flexibly. Thus, the vehicle employs inboard and outboard CV joints to permit the torque through a wide array of angles.

In rear-wheel drive applications, operating angles are much lower and less stress is placed on the CV joint as a result.


A dusty dirty CV joint.

CV Joint Problems

A CV joint is a collection of many components (bearings, race, cage, housing and balls) connected together in a precisely fitted assembly. All the parts spin around in a protective layer of special grease which is held inside the joint assembly. The assembly is packed and sealed tight with flexible rubber boot held in place by clamps and prevents the grease coming out of the CV joint. The boot also keeps the joint safe from outside contamination and keeps dirt and grime out. A CV joint doesn’t require any kind of regular maintenance and can perform very long if the rubber boot is not damaged. Over time, rubber boots fail from age or can become cracked, torn by road debris.
The most common problem with the CV joint is damaged boots. Once the boots get damaged, grease makes its way out and moisture and dirt get into the CV joint assembly. This will ruin the CV joint by causing it to wear out faster and fail eventually. Outer CV joints boots fail earlier than inner ones as they have to endure more strains due to more angles.

Signs of a failing CV Joint

CV joints may fail as a result of a lack of lubrication or the introduction of contamination. In extreme cases, a badly worn CV joint can disintegrate while driving leaving a vehicle undrivable. Most often, a failing CV joint will cause a loud clicking noise while turning. To confirm, crank the steering wheel to one side and drive around in circles either backwards or frontwards. If the noise gets louder  then you can feel pretty confident that you’re dealing with a CV joint issue.

Don’t waste time putting off repair of this one. You will either end up with an undrivable vehicle or as if often the case, a much higher repair bill when you have to fix the vehicle axels.

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