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96-00 140 amp alternator upgrade

Discussion in 'Chevy Trucks' started by jb1390, Feb 11, 2011.

  1. jb1390

    jb1390 Senior Member
    Messages: 710

    My particular truck is a 1998 chevy 2500 with a 5.7. The alternator was starting to sound a little worn (minor bearing noise), so I know it was nearing replacement. I run significant extra lighting at night (4x 55 watts reverse lights, 4 x 55 watts headache rack lights, 2 x 55w under bed lighting, 2 x 55w in the strobes, plus 2x 55w headlights) That is all additional to whatever the stock requirements are for fuel pump, etc. 660 watts results in 55 amps just in lighting, and I recently added an electric fan for a transmission cooler.

    Needless to say, I looked into a more powerful alternator for an upgrade since I was doing the replacement. I run dual batteries, and the alternator does an ok job of keeping up, as long as I shut off the lights in between driveways and let the alternator catch up. It turns out, that chevy made some of these vehicles with a larger (140 amp) alternator instead of the 105 stock alternator that I had. This alternator is physically larger, which i prefer over a rewound small bodied alternator. I have seen a chart that shows this alternator will put out 80-100 amps at idle, as it was designed for police vehicles, ambulances, etc.

    I am very happy with the install. With the old alternator, the voltage would drop significantly with the lights on, now with everything on, it dips for a split second, then comes right back up past 14 with everything turned on.

    What you need:
    CS144 alternator-just ask for a 140 amp alternator for this year vehicle
    1/2" longer belt
    Repair harness for 140 amp alternator-Napa had this in stock. You can also find them online. The plug is a different shape than the 105. There are multiple wires on the pigtail-my alternator plug only used one wire, it goes to the same position on the new connector (middle wire on the 3 pin harness i purchased)
  2. jb1390

    jb1390 Senior Member
    Messages: 710

    The last pic is the voltage with EVERYTHING turned on, at idle. And yes, I know I need to fill up on gas.






    NICHOLS LANDSCA PlowSite Veteran
    Messages: 4,362

    Good info and with picsThumbs Up Two of my trucks have the same set up, kinda funny my Freightliner takes the same alternator.
  4. Raconteur

    Raconteur Senior Member
    from MA
    Messages: 138

    You have made a huge improvement to your electrical system . That big alternator with high quality battery and clean connections is the only way to go . The low amp alternators are a weak link .

    Now instead of watching the gauge drop and stressing out, you can just plow .
  5. sweetk30

    sweetk30 PlowSite.com Addict
    Messages: 1,588

    only think i think i didnt see or read was 4ga wire upgrade from alt + stud directly to battery + stud. the stocker is weak for high amp draw stuff.
  6. jb1390

    jb1390 Senior Member
    Messages: 710

    Yep, the stock wiring also needs to be upgraded. I have the wire, I just need a new ring terminal next time I am at TSC or napa. Also, I solder all connections for battery cables, etc now. I find that salt and water causes corrosion inside the crimps, and a soldered joint will only ever corrode externally. If you use acid-core solder (generally used for metal work), you can solder some very corroded wires.