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91 GMC Sierra Alternator Issues


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jake84
New User

Oct 25, 2014, 1:09 AM

Post #1 of 9 (1421 views)
91 GMC Sierra Alternator Issues Sign In

Hi,
I have a question in regards to alternators. I'm currently on my 3rd alternator in a years time and looks like I'm soon going to need my 4th. The alternators in question are remanufactured and have a lifetime warranty. I've been doing some research and have concluded that remanufactured alternators are kind of like a needle in a haystack and may take a while to find a good one, 4 however seems a bit excessive. Is this somewhat common for remanufactured parts or do you guys think it could be something more? Any advice on what I could check before taking it to a shop? The vehicle in question is a 91 Gmc Sierra 350 4wd. Any advice is greatly appreciated.


(This post was edited by jake84 on Oct 25, 2014, 1:42 AM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 25, 2014, 2:58 AM

Post #2 of 9 (1410 views)
Re: 91 GMC Sierra Alternator Issues Sign In

Hmmm? Couple issues with multiple alternators needed for this. Remanufactured is somewhat unknown as to what the old core that was fixed was like and what was really replaced new or just cleaned up. The failure rate is and has been much higher with remans vs new.


Also consider the battery and know what power you need. Battery and alternator rely on each other quite a bit and can take each other out or stress the weaker.


Neither like working hard or more than what they are rated for. When you run down a battery for any reason more than it took to start the vehicle it's harming it and alternator working full tilt to recharge it harms it. You can feel that (careful now) as alternator will be hot to the touch working toooo hard imo if you notice that.


Batteries don't like being fast charged either from a low state of charge.


You can test out the battery and charging system and get a good idea of its condition would help. Suggestions by me will include aim for the best quality for batteries, alternators and any cables plus all connections.


There's a problem over some years with all this. Copper got expensive (cables) and IMO quality of plain lead used in batteries doesn't seem to be up to snuff. Lead cable ends are gone now and were better than the newer metals used so it's a battle.


So - keep buying the warrantied items but keep a sharp eye on system and don't delay fixing when first noting a problem. For this alternator roulette see if you can trade up to new,


T



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 25, 2014, 5:54 AM

Post #3 of 9 (1400 views)
Re: 91 GMC Sierra Alternator Issues Sign In

Let me ask you this............ Do you have an aftermarket amplifier in the truck? Do you use your vehicle to "jump start" other vehicles?



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



jake84
New User

Oct 25, 2014, 6:07 AM

Post #4 of 9 (1396 views)
Re: 91 GMC Sierra Alternator Issues Sign In

Thanks for the quick response, guys! So, I got to work last night, parked and went to work. Lunch time rolled around and I got in my truck and wouldn't start. Luckily where I work we have a battery diagnostic/charging machine. Charged the battery, put it back in this morning and drove home with the battery light still on and the meter on the dash showing nearly no activity from the alternator. As I was about to turn off the truck, the alternator sprang to life. My interior lights got bright, headlights, etc. So I went and popped the hood to see of I could notice anything at all. The tensioner pulley was dancing around like mad. Then all of the sudden it stopped moving and boom, the battery light came back on and nearly no activity from the alternator. I'm not mechanically minded, but this seems like it may be related. Any thoughts?


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 25, 2014, 6:15 AM

Post #5 of 9 (1391 views)
Re: 91 GMC Sierra Alternator Issues Sign In

That just sounds like a bad alternator. I think you already knew that.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 25, 2014, 6:17 AM

Post #6 of 9 (1388 views)
Re: 91 GMC Sierra Alternator Issues Sign In

Quote HT ">>Do you use your vehicle to "jump start" other vehicles?<<"


Excellent point on that and if any other item is overworking system. I certainly have stressed out my own assorted vehicles with road calls and jump starts trying to only use both running vehicles for short times at a time till enough but it's still too hard on alts and batteries - both donor and the dead vehicle. Much prefer to charge the dead/low vehicle with a charger ASAP so it doesn't work so hard after just starting. Can't always do that and motor clubs don't that I know of.


If you do that for another same vehicle it's killing yours if doing it all the time. Get a jumper box just anyway if need to jump start other things or vehicles a lot,


T



jake84
New User

Oct 25, 2014, 6:27 AM

Post #7 of 9 (1383 views)
Re: 91 GMC Sierra Alternator Issues Sign In

I have jump started people in the past, but not with the current alternator I have, at least not that I can remember. As far as aftermarket stereo parts, no, I believe it's all pretty much stock. I'm going to get in touch with the place I bought the alternator from and do as suggested and see if I can't just trade up to a new alternator instead of another remanufactured one.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 25, 2014, 6:42 AM

Post #8 of 9 (1378 views)
Re: 91 GMC Sierra Alternator Issues Sign In

If 105 amp alternator a new one isn't that expensive or the difference in price not so bad if that one. $114 - trust me that's cheap as things go.


OK - I will still (long done with this stuff mostly) re-do my own almost always just a bearing, brushes or diodes and some you can just clean up brushes with fine sandpaper and they behave as new again! Fine but that's not good as new! Makes me wonder what really is remanufactured, what new in them and what is just cleaning and making them pretty????


T



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Oct 25, 2014, 12:15 PM

Post #9 of 9 (1367 views)
Re: 91 GMC Sierra Alternator Issues Sign In

You might have trouble even finding a place that carries a new one. Most all alternators sold these days are reman units. The difference is the company that built it. I wouldn't give up on remans yet but I would try to change brands, preferably to a Delco unit.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







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