Replace Brushes or the Alternator Itself

I have a 1991 Honda Accord that still has the original factory
alternator in it (173k miles). The charge light came on and I took it
to an auto electric shop today and he simply said it needed a new
alternator.

How does one know if all one needs is to replace the brushes or if the
alternator really does need to be replaced?

Thanks,

Tim

 

Remove the brush holder from the rear of the alternator (a few screws). See
if the brushes are worn down past their limit. You can buy a new brush
holder from the dealer (~$30), or solder on new ones yourself.

If new brushes doesn't fix the problem, you need the old alternator
remanufactured.

 

150-200K miles is about the life expectancy for brushes, and worn brushes
are the most common cause of alternator failure. I'd go in that direction
first. Be sure to disconnect the battery before removing the brush assembly!

Mike

 

OR even cheaper from an auto electric supply house. The last time I
bought brushes they were a buck a piece.

Failing that the regulator rectifier can go bad as well but this part is
harder to get and can cost almost as much as a cheap re-built alternator.

-SP

 

Wow. On an old Celica I spent a whopping $38 to rebuild the alternator.
The brushes were ~$1 each, and the regulator was $36. An afternoon with a
screwdriver and a 10mm wrench and I once again had a good working
alternator that lasted the rest of the life of the car (275,000 miles)

Check the bearings, too. The bearings seized on an '85 Corolla I have. I
didn't replace them when I did the brushes as they were still in good
shape, and now I can't get the alternator off the car!