question about alternator going bad

[fan of fanboys]

so previous owner of my 4runner put in a battery gauge and it normally reads 14.4

yesterday I was driving and it dropped down to 11.4 and stayed there and the battery light on the dash came on

so I stopped at an auto store and they did a test and said alternator was bad. I decided I would look online and order

well, today I had to run a few errands and the battery was back at 14.4 entire time and no battery light on the dash

so it seems like the alternator is back to charging the battery

my questions: 1) does an alternator slowly go out? will it sometimes work and sometimes not until it fails? or does it go out all at once? 2) if it does fail all at once then what was my issue yesterday?

 

[thecole1098]

You might get lucky, but typically once it does start acting up it will just get worse and eventually fail all together.

 

[nissanh]

IS your alternator OEM or aftermarket?

 

[fan of fanboys]

IS your alternator OEM or aftermarket?

pretty sure OEM

the previous owner gave me all the work he had done and that was not on the list

I am at 261K miles

 

[cblock406]

I said the same thing in another alternator thread but I'll say it here too:

My electrical system would shut off and instantly come back on with the battery light showing on the dash afterwards. It did this for a couple of months and unfortunately I didn't get to the alternator before it finally went out on me in traffic.

I would replace yours before that happens to you.

Link to my debacle:
http://www.toyota-4runner.org/2827996-post50.html

 

[HiLife]

You should replace the alternator, preferably with another oem one or a rebuilt Denso.
If you don't replace it now, at least have a backup unit in your 4r and the tools so you can replace it in some parking lot when it does go.

 

[phattyduck]

Sounds like the brushes are worn out. They are making intermittent contact, causing the unreliable output. If the diodes or regulator burn out, they won't magically heal themselves.

As others have said... get an OEM rebuild or have your current one rebuilt with good parts to keep OEM-like reliability.

-Charlie

 

[mtbtim]

Check your brushes first. Very affordable and easy to do. You don't need to pay anyone to do this for you.

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