Alternator Died. Why?

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Frank Enstein

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I tried searching again, this time explicitly adding '1994', and I found some on eBay.

One is equivalent to stock (105A) and another is high output (300+A). Is there any harm in upgrading to the high output model, or should I stick to stock?

c
The only harm from a high output alternator is to your wallet. It will only put out what is demanded of it. And you should upgrade the charge wire too.
Changing an alternator is a good place to start learning vehicle repair. I mean you can work a voltmeter and zip ties! You are already more skilled that most!:biggrin:
 

cc333

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Thanks :)

Years ago, I was able to change the power steering pump and -- with the help of a neighbor -- the starter on a 92 Ford Explorer, so I figure this couldn't be too much different.

In fact, working on this GMC seems pretty straight forward by comparison.

Anyway, I got some help from a friend who has some tools, so now I just need to get the alternator.

...you should upgrade the charge wire...
OK. Is there a ready made cable I can get? If so, I'll order it along with the alternator.

c
 

thinger2

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At 106 it could be just total lack of maintenance or it sat for a long time.
Pretty unlikely that the odometer has been rolled back.
It just isnt worth the effort on these.
But the entire cluster may have been replaced with a lower mileage cluster.
That does happen.
Alternators do suddenly fail.
They whining noise was the clue to at least take a look at what was whining.
Like most things in life, screaming is a sign that things are not going good.
As everyone has mentioned, dont buy a cheapo reman unless you have no choice.
Try to find an alternator/ Starter/ electric motor repair place.
You can rebuild them yourself and it is actually pretty easy.
I stopped doing that a couple of years ago because I cant buy good parts anymore.
I take them to a place called "The Rebuilder" in Kent, wa.
I know that doesnt help unless you are in the Sea-Tac area

But this is an old school operation that has oem 90s parts
Rebuilds them while Im out eating breakfast and costs about the same as a garbage reman from the parts roulette stores.
Try to find a local rebuilder first.
 

Frank Enstein

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Thanks :)

Years ago, I was able to change the power steering pump and -- with the help of a neighbor -- the starter on a 92 Ford Explorer, so I figure this couldn't be too much different.

In fact, working on this GMC seems pretty straight forward by comparison.

Anyway, I got some help from a friend who has some tools, so now I just need to get the alternator.


OK. Is there a ready made cable I can get? If so, I'll order it along with the alternator.

c
You can buy them but they are easy to make.

https://www.summitracing.com/parts/sum-810004

Is an example. It's just wire and some ring terminals.

I don't see the need for the fuse because the wiring is pretty short and it's easy to keep the wire out of trouble.
 

cc333

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I see, OK.

I was just doing a little research, and there's this notion of one-wire compatibility. I presume this is the thin wire that goes into the connector on the side of the alternator.

Anyway, there are numerous replacement alternators (AC Delco reman units), all of which state, "one-wire capable: no." This is obviously important, so is it possible to rewire the truck to accept a "multi-wire" requiring part?

If not, there seems to be different part numbers for what appear to be otherwise identical parts, which suggests that maybe some are one-wire capable and some are not, depending on the part number (all of those that state they're not one-wire capable are part number 335-1023, if that matters).

EDIT: Never mind. It seems that one-wire simply means that only the big wire in back and a good ground are needed for such an alternator. This is irrelevant to the stock alternator or any compatible substitutes thereof.

GM used a pretty wide variety of similar, but different and not necessarily 100% cross-compatible parts, even within the same model and year, didn't they? Such isn't unusual I suppose, but it sure can be confusing for the uninitiated, such as myself!

c
 
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1989GMCSIERRA

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Usually the diodes blow or the regulator. But that’s usually doe to time age use heat or construction. If you’re buying cheap china rebuilt alternators they tend to fail. Usually frequently and at inopportune times.
live never had a rebuilt alternator last more than a year or so. I only buy factory new or aftermarket brand name new. the internet has made shoppigna lot easier nd yiu cn research your prices. A rebuilt is ok as Get me to work on Monday if I broke down on Friday thing. But replace it and keep,the rebuilt as a back up
 

1989GMCSIERRA

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I tried searching again, this time explicitly adding '1994', and I found some on eBay.

One is equivalent to stock (105A) and another is high output (300+A). Is there any harm in upgrading to the high output model, or should I stick to stock?

c
Nothing wrong it’s going to a higher output but make sure yiu know who built it. A lot of times these cheap manufacturers will install a a smaller pulley making the alternator spin faster which wears it out sooner.
see where it’s made
 
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