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Alternator

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Strahan, Feb 7, 2004.

  1. Strahan

    Strahan 1/2 ton status

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    Driving home two nights ago coming down the highway and I say to my girl.. damn, these headlights are dim. I can barely tell they're on! I notice that the dash lights are dim too but they're turned up all the way. Check the volt meter it's in the red zone. So, I guess I can scratch an alternator. I figure if I have to replace it, I should replace it with something beefy.

    What's a good high amperage alternator to throw in my 83 Jimmy? Thanks!
     
  2. Strahan

    Strahan 1/2 ton status

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    BTW I'm just assuming the alt. is bad. How do I test it? Is there something else that could cause that behaviour?
     
  3. k20

    k20 3/4 ton status

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    start the truck and hold a flatblade screw driver near the flat, round piece on the middle of the back of the alternator, if its pulled strongly to it, the alt is good, if it does nothing or if its VERY weak the alt is bad.
     
  4. Strahan

    Strahan 1/2 ton status

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    Thanks. I called Auto Zone and they had a cheapy reman alt. for $50 so I figured I'd just throw that on for now so the truck's back on the road. Just installed it and fired her up. Hooked a volt meter to the battery and it read 11.21 volts, then every 3-5 seconds it'd drop a hundredth. After several seconds I was down to 11.17. Got in and set a block on the accelerator to rev it up and measured again, and it went back to 11.22 but still dropped, just took longer. The battery is only two weeks old and it now has a new alternator.. what else could be causing it?? Thanks.
     
  5. Confedneck

    Confedneck 3/4 ton status

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    you need to burn in the brushes in the alternator, go for a spin around the block with it, then re-check the voltage.. it should be around 13.2-13.6 at idle and near 14ish at 2200-2500..
     
  6. Strahan

    Strahan 1/2 ton status

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    I took her out for a spin, went about a mile and a half. Came back and pinned the pedal again to let it rev higher and metered it again.. 10.05 and still dropping. I've heard you should change the voltage regulator when you change your alternator, but I didn't see one. Is it built into these alternators? If not, think that may be an issue?
     
  7. Confedneck

    Confedneck 3/4 ton status

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    have you tested the battery yet?? its a possibility the battery is fried, not accepting a charge..
     
  8. Strahan

    Strahan 1/2 ton status

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    Nah, not yet. I just figured since it's only a few weeks old it was fine. Maybe the alternator croaking took out the battery too..? -shrug- Welp, I guess I'll run back to Wal-Mart and bitch about how it won't hold a charge & get them to replace it for free /forums/images/graemlins/smile.gif
     
  9. Confedneck

    Confedneck 3/4 ton status

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    sounds like a plan! /forums/images/graemlins/thumb.gif
     
  10. Strahan

    Strahan 1/2 ton status

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    Well, I guess that was it! I called my local (Baltimore) Wal-mart and they said since I had no receipt I'd have to buy a new one. Called Wal-mart back where I used to live (Shrewsbury, PA aka Rednecks R Us) and they said "shuure thing buddy, bring yer dead bat-ry back in and we'll fix ya up!" hehe. Works good now. Voltage seems a little low, it idles around high 11s but as long as everything stays working that's fine by me, hehe.

    Back to the original question, does anyone know what the best or highest amp alternator is that I can throw on here? It's a 305 /w AC. I wanted to throw a nice one on now, but got impatient heh.
     
  11. spearchucker

    spearchucker 1/2 ton status

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    Batteries from Wal-Mart? /forums/images/graemlins/eek.gif /forums/images/graemlins/yikes.gif /forums/images/graemlins/doah.gif /forums/images/graemlins/shame.gif Don't you care about your truck? /forums/images/graemlins/rolleyes.gif
    Get the Optima Red top from Costco for $90 and be done with it.
    I have a PowerMaster 140 amp alt. Stock is somewhere around 60 to 80 amps. You can get a 200 amp alt from Wrangler or Premiere Welding (don't know their link) or you can get an 800 amp alt from Zena . Most people find that a 140 amp is sufficient. Expect to pay about $1 per amp until you start playing with the exotic alts.
     
  12. bablazer73

    bablazer73 1/2 ton status

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    Do a voltage drop test on your cables. If your cables/ends are no good, The juice WON'T get back to the battery.
     
  13. Strahan

    Strahan 1/2 ton status

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    I guess I'll have to try that now /forums/images/graemlins/frown.gif I just got back from driving around and the !@#&*@#^%@ voltage is back down to the red zone again. I guess the false sense of victory was from putting in a fresh battery, it appeared to be fine cuz all the power was back.
     
  14. Strahan

    Strahan 1/2 ton status

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    I just read somewhere that I should also check for a short. It said disconnect - and hook a test light between the batt - and the disconnected - lead and if it lights, I have a short. Well, I don't have a test light but I have a voltmeter. I metered the batt - to cable - and got 10.78v and rising so -sigh- I guess I have a short, eh?

    Anyone in/around Baltimore good with electrical issues? /forums/images/graemlins/grin.gif
     
  15. dave_90_blazer

    dave_90_blazer 1/2 ton status

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    lets forget the possible short/draw, and concentrate on the charging system.

    ok, key on, engine off, you should have power at all the wires at the alt, all but one will be battery voltage, and the one(usually brown)will be lower than batt voltage

    check and post back
     
  16. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Buy a large case altenator from an electric shop. They are 100 amps stock and make almost full power at idle unlike most aftermarket alts. I got mine for 55 bucks. /forums/images/graemlins/thumb.gif Your current alt should be 78 amps with a/c, 63 without a/c.
    A 100 amp alt should be plenty as long as you are not running a huge stereo system.
     
  17. Strahan

    Strahan 1/2 ton status

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    OK, I went out and metered it. On the plastic plug that plugs into the side the red wire was same as batt +, 11.48. The black wire was 2.69v. The red wire going to the bolt on the back of the alternator also read 11.40 something.
     
  18. Strahan

    Strahan 1/2 ton status

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    Allrighty, think I have it tracked down. Came home for lunch and hooked up the meter to the batt - and disconnected - cable. 11.70 some volts. Went thru unplugging almost every fuse in there, no change. Then I thought to check the alternator. Unplugged the two cable plastic connector and the voltage dropped out. Checked the alternator pins and no continuity then checked and found continuity from the red wire to the + AND the - term of the batt and - cable. Ugh. So I guess the problem is in the cables from the starter?
     
  19. Strahan

    Strahan 1/2 ton status

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    OK, I went back to Autozone and they tested the alternator and said it was bad. The one they just sold me heh. So they didn't have any more of the Valucraft reman'd in stock so they gave me a new Duralast even trade /forums/images/graemlins/smile.gif Got in, fired it up and the meter in the truck was up over 13. Whew! Hopefully it's fixed for real this time, heh. Thanks for the help guys.
     
  20. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    Living where I live, parts stores are always at least 25-30 miles away. I got two bad parts before, and since then I have the store test the NEW stuff before it goes out the door. They do kind of look at me funny though. /forums/images/graemlins/smile.gif

    John
     

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