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How to Change an Alternator

Omkar Phatak
Here, we have provided a general procedure for changing a car's dynamo or alternator.
Every modern automobile has a variety of electrical accessories which require a considerable amount of electrical power to be operational.
A standalone car battery without regular recharging cannot supply the electrical power required by the car. It is because of the alternator, which is the car's dynamo, that the electric power requirements are met.
All the vital electrical systems of the car, which includes the ignition system, are dependent on the alternator's recharging of the car battery. That is why a bad alternator can cause a lot of problems and needs to be replaced immediately.
Undertaking such car part replacement jobs on your own can save you some money and also give you an insight into how does a car work. Changing an alternator is quite a straightforward car repair job, but needs to be undertaken carefully.
Signs to Look For
  • One simple way of knowing when an alternator is not working properly is to check the service light on dashboard dedicated to it. If it is off, you have nothing to worry about.
  • Another symptom of a bad alternator is a drop in car battery's voltage. To check that, you will have to measure the voltage of the car battery using a voltmeter. If it is considerably below 12 V, then something may be wrong with the alternator, provided the car battery is working fine.
  • Also, when the car's idling, the car battery voltage should be in the 13.8 V - 14.3 V range. If it's below this value, then it means that the car alternator is not doing its job.
  • Sometimes, the problem is only with the alternator belt. In that case, there is no need to replace the alternator but only replace the alternator belt.

Replacing an Alternator

So, once you have confirmed that the alternator needs to be replaced, you need to prepare yourself for changing it. The tools you'll need for the job are wrenches, socket set, and a brand new alternator of the same make.
  • First thing to do is disconnect the car battery connections. Remove the negative terminal followed by the positive terminal.
  • Then what you need to do is locate the actual position of the alternator and take a look at all the connections associated with it. You will see a pulley associated with the alternator, along with a serpentine belt running over it.
  • To remove the alternator, you must remove this belt which brings in the torque from car's engine. Observe the belt's tensioner bolt and select an appropriate wrench to loosen it.
  • Once the bolt's loose, the belt will go slack and it can be easily slipped off.
  • Next part is removing the old alternator. Locate the bolts that fix the alternator in place.
  • Disconnect wires associated with the alternator and remember the order in which they are connected.
  • With appropriate size wrench, unscrew all the alternator fixing bolts. Then you can easily remove alternator from the assembly and begin second part of alternator transplant procedure.
  • Put the new alternator in place, exactly in position as the old one.
  • Fasten the bolts back again and fix the alternator in position.
  • Fix the wires associated with it, exactly as they were in the old one.
  • Slip the serpentine belt back in and tighten the tensioner bolt till the serpentine belt is sufficiently taut.
This finishes the procedure of changing the alternator. Connect the car battery back again and test the alternator functioning, by checking the car battery voltage in standalone and engine idling condition. If the testing gives good results, you have done your job well.