Automotive Repair Library, Auto Parts, Accessories, Tools & Equipment, Manuals & Books, Car BLOG, Links, Index
How To Replace an Alternator
Copyright AA1CarShare
.
.
.
.
Replacing an alternator is not a difficult job on most vehicles. All you need are some basic hand wrenches or sockets to loosen the alternator mounting bolts.
To replace your alternator, proceed as follows:
1. Disconnect your battery. NOTE: If you have a 2004 or newer vehicle, see the related article on Battery Disconnect Precautions.
Use a battery memory saver if the modules in your vehicle would be affected BEFORE you disconnect the car battery.
The reason for disconnecting your battery is to prevent any shorts or grounds that might occur if you accidentally touch a battery
positive wire at the alternator against anything metal. The sudden voltage surge could damage sensitive electronics in your vehicle or the wiring. There is
NO danger of being shocked by 12 volts.
2. Remove the alternator drive belt.
On newer vehicles with a serpentine belt and automatic belt tensioner, locate the belt tensioner and use a socket and long handle to rotate the
tensioner. the direction you turn the tensioner will depend on how it is mounted and how the belt is routed. On vehicles where the tensioner is hard to reach, you may have to do this from underneath the vehicle, or it may
require using a special long handle serpentine belt tensioner tool.
NOTE: Before you remove a serpentine belt, look for an underhood decal that shows how the belt is routed. If you can't find such a decal, draw
a picture of how the belt is routed, or take a digital photo so you can refer to it later when you put the belt back on. The routing of some belts
can be very confusing, so make sure you know how it is supposed to be routed BEFORE you take it off.
If your vehicle has a serpentine belt for the alternator but there is no automatic tensioner, use the same removal procedure for a V-belt
(loosen the alternator pivot bolt and adjustment bolt, rotate the alternator inward to loosen the belt, then remove the belt).
On older vehicles with a V-belt, loosen the alternator pivot bolt and the adjustment bolt on the alternator support
bracket. Swing the alternator inward to relieve tension on the V-belt, then slip the belt off of the pulley.
3.Disconnect the wiring from the back of the alternator. In some instances it may be easier to disconnect the wiring after the alternator
bolts have been removed and you can turn or rotate the alternator for easier access. But you don't want to twist the wires too much, and you
certainly don't want to let the alternator hang by its wires as doing so can easily damage the wiring connectors or terminals. That's why we
recommend disconnecting the wires BEFORE you remove the alternator.
NOTE: On alternators that have multiple wiring terminals or connectors on the back, pay attention to which wires attach to which connectors.
In some cases, it may be possible to reinstall the wires on the wrong terminals, preventing the alternator from functioning or possibly damaging it or
other electronics in your vehicle.
.. 
4. Unbolt and remove the alternator. Alternators usually have either two or four mounting bolts. On applications where the position of the
alternator can be adjusted to tighten the belt, two bolts are standard: a large pivot bolt (which usually has a hex nut on the inside end), and a
smaller adjustment bolt on the alternator support bracket. On applications where an automatic tensioner is used to maintain belt tension, the
alternator is usually rigidly mounted to the engine or front cover with four bolts.
|
|
Warning: Never disconnect a battery cable while the engine is running to "test" the alternator. Doing so can cause high voltage spikes that can damage the alternator as well as other electronics.
Use a battery charger to recharge the battery. If your battery has run down, recharge it with a portable battery recharger BEFORE you start your vehicle. This will reduce the initial load on your new alternator and the risk of overheating it.
Test the battery to make sure it is still good. The condition of the battery should always be tested if it fails to hold a charge or a charging problem is suspected. The problem may be an old battery that needs to be replaced, not a bad alternator.
Install a new serpentine belt or V-belt. If your old belt has more than 60,000 miles on it, it may be worn and should be replaced to reduce the risk of slippage. Replace any belt that is cracked, damaged or contaminated with oil or grease.
Check the automatic belt tensioner. If the automatic belt tensioner is rusted, weak or stuck, it won't maintain the proper tension on the serpentine belt, allowing it to slip.
Related Articles: 
Click Here to go to AA1Car Automotive Technical Articles
