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Upgrading alternator issues

Discussion in 'Truck & Equipment Repair' started by pohouse, Dec 21, 2012.

  1. pohouse

    pohouse Senior Member
    Messages: 322

    '03 GMC Sierra 1500 5.3L upgrading 105 amp to 145 amp. Plugs are the same. Will direct swap work?
  2. 06Sierra

    06Sierra PlowSite.com Addict
    from Maine
    Messages: 1,329

    You will need a 1" longer belt. I just ordered one from Alternator pros a couple days ago. I got a 160 amp for $120. Locally it would have been closer to $200.
  3. Plowtoy

    Plowtoy Senior Member
    Messages: 929

    I have never done this, but wouldn't an alternator from say a loaded up Yukon Denali of the same year of your truck work ( I think that would be the 145A you are talking about)? So then wouldn't the belt from the same type of vehicle work? A 5.3 is a 5.3 is a 5.3 right? (o.k., maybe a 5.3 is a 4.8 or 6.0, who can really tell by looking at them??) Maybe I'm wrong but I can't see GM making drastic changes on the assembly line for belt lengths on same model year engine family, that's just me though.

    Farther more, a 145A should be more than enough for today's vehicles, even with all the plow accessories. I believe that today's vehicles use considerably less amperage than vehilces of years past. With all the lighting going to LED, and all the computers replacing relays, you shouldn't have any problems. I never use anything but O.E replacment alternators and batteries and have never had issues in not having enough power, the key is to have good functioning electronic's
    Last edited: Dec 21, 2012
  4. vegaman04

    vegaman04 Senior Member
    Messages: 378

    Don't forget to do the "Big 3" upgrade too.
  5. pohouse

    pohouse Senior Member
    Messages: 322

    Call me ignorant. Please elaborate on the Big 3.

    Actually, the oem 105 amp alternator has been sufficient for the past couple of years. It went out though and left the plow truck (and driver) stranded. The only replacement alternator NAPA had on hand was the 145 amp. It's a physically bigger alternator, same mounts and plug though. And yes, you do need a larger serpentine belt. The 145amp was actually $10 cheaper than the 105amp. payup
  6. blazer2plower

    blazer2plower Senior Member
    Messages: 544

    Bigger wires power and grounds. Go with 2gage wires.
  7. vegaman04

    vegaman04 Senior Member
    Messages: 378

    The "Big 3" is upgrading 1) alternator positive to battery positive, 2) battery negative to chassis, and 3) engine ground to chassis. Some people replace the factory wiring; others add additional cables to the factory wiring. I usually add to the factory wiring, by adding 2 gauge with soldered ends.
  8. blazer2plower

    blazer2plower Senior Member
    Messages: 544

    There has been a lot of talk of alternator and BIG 3 up grades can they sticky it somewhere