A properly functioning alternator will supply between 13 and 18 volts to your car's electronic and ignition system, while simultaneously charging your battery. But if the alternator delivers less than 13 volts, the battery will not remain fully charged. You can save money by replacing your alternator yourself with the steps in this article.
Step 1. Disconnect the positive battery terminal
This one should be red.
Step 2. Locate your car's alternator
Step 3. Loosen the tensioner with a wrench specially made for multi-belts and remove the belt from the alternator pulley
Step 4. Replace the bolts holding the alternator
Depending on your car, the alternator is secured with 2 to 4 bolts.
Step 5. Loosen the bolts with a socket wrench and remove them
Step 6. Remove the alternator, and disconnect the plug that makes the electrical connection
Step 7. Remove the alternator from the engine block and take it to an auto parts store to purchase a new or reconditioned one
Step 8. Inspect the new alternator while you are still in the shop so that you can compare the alternator with the old one
Check that the voltage regulator and the pulley are the same. If not you can ask if they can put the old pulley on the new alternator.
Step 9. Install the new alternator in reverse order
Step 10. Connect the plugs and wires to the new alternator
Step 11. Slide the alternator into place and tighten the old bolts into place
Step 12. Put the alternator pulley back in place with the bolts
Check the alignment in relation to the tensioner.
Step 13. Use your multi-belt tensioning tool to get the correct tension, then put the belt back over the alternator pulley
De-tension the device by applying tension to the belt.
Step 14. Reattach the positive battery terminal
Step 15. Start the car and check if the alternator is charging properly
- Take pictures when you are going to remove parts. This way you can later check which part belongs where. This also makes it easier to remember the order when you put everything back.
- If you cannot find the multi-belt tool, use the drawing of the belt that can probably be found in the engine compartment.
- An auto parts store will probably lend you such a tool in exchange for a small deposit.
- Have the voltage tested at a garage after you have mounted the alternator. The voltage must be at least 13 volts.
- Disconnect the positive battery cable before working on your car's electrical components to avoid shorting the electrical system.
- First tighten all bolts on the new alternator by hand, only tighten them with the wrench when they have all been tightened by hand.
- Let the engine cool down completely before working on it, otherwise you run the risk of burns.