89 Burb eating altenators????

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Ape, Jan 5, 2012.

  1. Ape

    Ape Member 100 Posts

    So I'm not quite sure what to do next on this bad boy. I replaced the altenator 2 times in the last year or so and my volt meter started reading a low voltage again today. So I broke out my charger and charged the battery to full and then tested the alt. I got 2 readings in a row that the alt was good so I figured my battery had given up on me and it was time for a new one. It was almost 10 years old so it made sense.
    So I put a new batt in and charge it to full just to be sure and then take it around the neighborhood to test it all out. The volt meter stayed around 14 the entire time so I assumed it was all good again. Then I went to pick my kid up from school today and it started dropping again!
    So I came back home and tested the alt again and got a good reading the first time and then 4 more bad readings after that?!?!?!?

    So now I'm trying to figure out why the heck my altenator would keep going bad on this thing? The one in there now can't be more than 3 months old, and it's not a refurb unit, it's all new.
    I can rebuild an engine and do most anything mechanical, but when it comes to electrical gremlins I'm pretty much useless. But nonetheless, I looked high and low trying to find a bad connection or obvious short somewhere to no avail.
    Any ideas that could point me in the right direction other than take it to a mechanic for an electrical diagnosis?

    TELORVEHC Rockstar 4 Years 1000 Posts

    How are the terminals and the connections on the alternator? Are they clean? Are the wires frayed or loose anywhere?
  3. Ape

    Ape Member 100 Posts

    Nope, all the connections are good and the wires aren't frayed or cracked with exposed copper. At least as far as I could see. I haven't pulled all the wires under the dash or anything, but everything up to the firewall looks good to me.

    I haven't researched it yet, but is there a voltage regulator on this year vehicle that could be going bad and causing this?
  4. janikphoto

    janikphoto Rockstar 3 Years 100 Posts

    Yeah, my first thought was "stop buying cheap refurb alternators", but you are buying new units... hmmmm... trace the cable and look for any sign of arcing, split insulation, kinked/broken wire, etc. Something must be putting undue strain on these things. How about using header wrap on any exhaust that is near the thing. Keeping extra heat away from it will also help it out.

    Oh, and a ten year old battery? You mind as well replace it, too. It is at the very end of it's life. Most batteries will only last 3-4 years, but a well-maintained battery can give 5-7 years... ten, if you're lucky!
  5. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Voltage regulator is part of the alternator on that model.
    I'd say you've got a short somewhere thats causing this, finding it wont be easy.
  6. Ape

    Ape Member 100 Posts

    I thought the regulator was part of the alt, but I wasn't sure. Thanks!

    After pulling the alt this morning I noticed the terminal on the back was loose and wobbling around. I tried to tighten it up but I couldn't do it without opening it up and ruining my warranty. So I took it back for the warranty and got another new unit and installed it this morning.
    So far so good as far as my volt meter is telling me. I made another search to see if I could find any bad wiring just because I'm still leary about this being my 3rd alt in less than a year, but I still couldn't find anything? So I'm hoping this is just a weird round of bad luck.

    ---------- Post added at 11:10 PM ---------- Previous post was at 11:05 PM ----------

    Nothing too close to anything to give it too much heat IMO. And wrapping those exhaust manifolds would be a major pain without taking them out (again). I wrapped the headers on my Chevelle when I dropped a new motor in it and it makes a nice difference. But when I had to change out my manifolds on the Burb (because one was cracked) it was a royal pain. So I'd rather not have to go that route unless I have to.

    As far as the battery is concerned, that was the first thing I changed since it was so old. But to be honest it was still working just fine. Didn't hurt to change it before it finally gave out on me right when I didn't want it to, but I'm still amazed at how long it lived in that truck!
  7. frank10

    frank10 New Member

    I am working on my grandson's 96 gmc surburban. It has a history of the same problem. The alternator checked ok on voltage until the driving lights
    load then it just stayed even on the voltage. Would slowly drain the battery. I found the problem on the curtesy light circuit. It would work ok if driven
    often. It run the battery low when parked for aday or two. I think with the battery being low it overworked the alternator. It has had several alternators
    It has had several perlaced in the past. Brought to my house to see if I could find the problem. Isolated the
    current draw to the curtesy light circuit. Removed the fuse and am now in the process of trying to get a
    wiring routing so Ican isolate the problem. It is pulling about the amount of current of the lights with none of them showing any light.
  8. Ape

    Ape Member 100 Posts

    Actually I think I may have finally figured out what my problem has been (knock on wood!).
    I finally found a few wires that were frayed and could have easily been shorting things out along with another one that was starting to melt on one of my exhaust manifolds. I only found them because I started it one morning and after it was warmed up I turned on the heater only to have it shut everything down. It did that to me 2 or 3 times until it wouldn't restart anymore and I had no power to anything in the truck.

    So I started by checking my connections at the battery and found that my positive connection was a bit "hinky". So I replaced that and then went underneath the truck to give another good look around for bad wiring. I knew my problem had to be other places rather than just the battery connection, and low and behold I found some bad wires underneath by the firewall. One was a starter wire and the other 2 were ones that I couldn't identify. But they were definitely bad so I replaced them by splicing where they were bad and back as far as I could go. I also replaced my drivers side door pin for the dome lights since it was bad and sometimes causing the dome lights to stay on. I had removed the bulb a while back to avoid battery drains from it, but since I was in the electrical mode I figured I should get that fixed too.

    So far everything seems to be working better than before. My volt meter is reading better higher and more consistantly than it ever has before for me, so I'm hoping I've fixed my electrical gremlin finally!

    Next I need to take my distributor off and see if it needs replacing. The guy who had it before me (my best friend) had rebuilt the top end and also replaced the oil pump. After doing that the oil pressure was always really high around 60lbs. I always thought that was a bit high for a stock engine such as this, but I figured too high was better than too low so I didn't worry about it. But recently the pressure went down to 30lbs and no higher out of no where? And once it's warmed up the pressure starts getting lower and lower?!?!? And when it's really warmed up and I stop at a light the pressure shows 0!?!?!? But if I left foot brake and add some rpm's it'll bring it up to 15lbs or so at rest. So I'm thinking maybe my distributor has issues and isn't connecting to the pump correctly????

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