How to Change an Alternator
Changing your alternator is not a job for the average do-it-yourselfer. It requires someone with a good knowledge of engine repair and mechanical skills. If you are unsure of the task at hand, you are better off leaving it to the professionals.
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| Alternator repair |
An alternator is an electrical device located in the engine compartment of your car. Its job is to generate electricity to charge the battery. It does this through a connection to the engine drive, and as it spins, it creates electricity.
The electricity is created when the rotor, a selection of rotating magnets, passes at high speed over a nest of copper wires, called the stator. A regulator is also part of its components, to ensure that the right amount of electricity flows around the vehicle.
You'll need a range of tools, the new alternator and a replacement alternator belt. Among these tools, you'll need a belt tensioner, a voltmeter and a few other items to keep life nice and simple.
Step 1 - Protect Your Vehicle's Electronic Preset Information
Depending on your vehicle and repair manual requirements, you may need to use a memory saver to capture all your electronic preset information.
Once you have that sorted, disconnect the negative battery cable.
Check your alternator belt to determine if it is a V-belt or a serpentine belt. A serpentine belt will be flat and thin with ribs on the bottom. A V-belt (no surprise here) is V-shaped. If your alternator uses a V-belt, you can proceed to step 5.
Step 2 - Loosen the serpentine belt
The belt tensioner is spring loaded, so be very careful not to hurt yourself if it snaps back into place. Keep your hands clear whenever you can. The job will be much harder if you have to do it with one hand!
Loosen the belt tensioner for easier access to remove the belt. You may need to be patient with the belt as it can be quite difficult to move or remove.
Step 3 - Remove the belt
Once you loosen the tensioner, it should make it easier to remove the belt. At this point, it's a good idea to check the belt tensioner for proper operation. If it's not working properly, if it's rusty or if it's catching, it's time to replace it.
A belt tensioner will give you extra leverage and better access to tight areas. If you don't have one, you should consider adding one to your toolbox. It makes the job much easier than a standard socket wrench.
Step 4 - Remove all connected parts
Be sure to label all wires and attachments so you can be sure of what goes where when it comes to reassembly.
Step 5 - Loosen the alternator
If you have a V-belt, you must loosen the alternator before you can remove the belt. It is the alternator that provides the belt tension in these cases, not a separate tensioning piece as with the serpentine belt.
Step 6 - Install the new alternator
You want to ensure a good fit. Align all the bolt holes and tighten the bolts to the correct tension.
Replace all connecting components with their correct counterparts (as you previously labeled them).
Next, replace the belt. If you're having a little trouble with this, there are a few tricks to putting the belt back on your alternator. Some alternators have a cross bolt that will allow the alternator to move on its mount. This allows you to adjust the tension of the belt.
If there is no cross bolt, you can use a "cheat sheet" to hold the alternator in place while you tighten it into its proper position. Alternatively, a good helper can help you keep the belt taut while you tighten the mounting bolts.
Read also: Top 10 Signs of Alternator Problems
Step 7 - Check Belt Tension
Without the proper tension, you can create real problems. Check your repair manual to see how tight your belt should be. After a few days, you should recheck the tension to make sure it is still correct after a period of installation.
Step 8 - Reconnect the battery
Reconnect the negative terminal of your battery, plug in your voltmeter and start the car. The correct output from your alternator should now read 13.1 to 16.5 volts. If your reading is correct, then you are done. Pat yourself on the back and reward yourself with a nice cup of tea.
How much does it cost to replace an alternator?
Replacing an alternator at a garage can cost you anywhere from £100 to £700, with an average price of between £300 and £400. You can expect higher prices at car dealerships and franchises.
For high-end cars, of course, you can also expect the price to rise accordingly. You could pay anywhere from £500 to £1,000 for an alternator replacement on a luxury model.
How to repair an alternator
Again, this isn't a job for just anyone. Fixing an alternator is not for the faint-hearted. It's not too complicated, but since the health of your car depends on it, you want to be 100% sure you can get the job done.
You'll need the right replacement components and your fair share of patience.
First, you'll need to remove the alternator from your car, as outlined in the process above. Next, you'll need to remove its plastic cover and check that the bearing is okay. It should fit snugly. If it is loose or stuck, it needs to be replaced.
Next, remove the resistors to access and remove the rectifier. You will need to disconnect the soldered wires before unscrewing the mounting screws. Then you can replace the old rectifier with its replacement by soldering the wires back together.
It is important to clean the armature shaft when replacing the brushes - this is your next step. Make sure the springs are correctly positioned when reassembling them.
All that's left is to replace the voltage regulator. If you've made it this far, then congratulations! This is how to rebuild an alternator. Now all you have to do is put it back together, put the belt back on and check that it works!