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Alternator defective? What symptoms occur and when to change the component

Content

1. Function of the alternator in the car

2. Typical symptoms of a defect in the alternator

3. Replace the generator of the car

The alternator supplies power for all electrical consumers in the car. In the past, it was only needed for the headlights, but today it is indispensable for the reliable power supply of many components. If the faithful power generator is defective, this is often only noticed when the charging indicator light lights up. But other symptoms can also indicate failure.

Function of the alternator in the car

The alternator in the car supplies the voltage required for operation. For this purpose, the component, which is also known as the Lima, alternator or alternator, is driven directly by the engine via belt pulleys. When the engine is running, the alternator is also in operation. The alternator converts the mechanical energy applied via the pulley into electrical energy. This is required for the consumers in the car and for charging the car battery.

If the alternator does not supply any or only little current, for example when stationary at low engine speeds, the battery steps in as a voltage buffer. Today, three-phase alternators are mainly used as alternators in cars. A charge controller is integrated directly into the alternator. In modern vehicles with hybrid drive and 48-volt technology, the alternator is often designed as a starter generator. This component combines the alternator and starter.

 

Defective alternator – replacement or repair?

When the alternator is defective, the question often arises: Replace or repair? Both procedures are possible. Some specialist workshops offer repair of alternators, which usually requires the alternator to be sent in. This can be worthwhile for classic cars, for example, for which an alternator is difficult to obtain. Otherwise, it is often worthwhile to replace the alternator with an intact one. If you don’t want to pay for a new part, it’s best to buy a used alternator from a car recycling centre.

Typical symptoms of a defect in the alternator

If the alternator is broken, certain signs often point to the defect. If the alternator fails completely, the battery is no longer charged. Without the power of the alternator, the voltage in the battery drops steadily. In this case, the charge indicator lamp in the dashboard lights up.

After a generator failure, the energy available in the battery is often no longer sufficient to start the combustion engine using the starter. Then the starter sometimes only turns slowly. The engine may also simply stop if the voltage required for ignition is missing. In addition, unusual noises can occur if a defect is imminent, for example if a bearing of the alternator is worn out.

Causes for a defective alternator

The possible causes for a defect in the alternator can be manifold. All alternator components are subject to a certain amount of wear. Especially in an older vehicle, the alternator can therefore fail at some point, regardless of whether it is in an Opel or a VW. Sometimes the charge controller of the alternator also breaks down. More rarely, the belt pulley wears out or breaks.

Replace the generator of the car

If typical signs point to a fault in the alternator, the part should be replaced. An original spare part that was also installed in this form on the vehicle is best suited for this purpose. The exact repair procedure may differ depending on the vehicle model. Different steps may be necessary for an Opel than for a VW.

Change the alternator in 6 steps:

  1. Check the alternator: The first step should be to check whether the Lima is broken. Other parts can also cause the typical signs, such as damaged cables or a worn battery. A multimeter can be helpful in measuring the voltage.
  2. Removing attachments: To remove the defective generator, numerous components in the engine compartment must first be dismantled, depending on the vehicle. The vehicle’s battery must also be disconnected before dismantling the generator can begin.
  3. Relax the belt: To be able to loosen the unit, the drive belt must first be slackened and removed from the pulley. If the part is already worn, this is an ideal time to replace it with a new part.
  4. Remove the generator: Before replacing the Lima with an intact one, all connecting cables must be dismantled. Only then can the screw connections and the entire component be loosened. The unit can then be carefully manoeuvred out of the engine compartment.
  5. Compare parts: After dismantling the defective component, it should be compared with the intact item. Manufacturers such as Opel or VW sometimes use different units for different engines. Original spare parts usually fit without any problems.
  6. Installing the Lima: If everything fits, the spare part can be installed in the engine compartment. To do this, the alternator is mounted and connected in reverse order. Then the generator belt is tensioned. After all parts have been installed, nothing stands in the way of a test.

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