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Thread: Transmission Overdrive

  1. #21
    Join Date
    Jan 2001
    Location
    Knoxville,Tennessee
    Posts
    2,639

    Default

    Maybe take your Alternator to a re-builder and have it checked? That's if there are still any around.
    "The Constitution is not an instrument for the government to restrain the people, it is an instrument for the people to restrain the government."
    -Patrick Henry


    A5150nut
    2006 K3500 D/A
    94 6.5 4x4 5spd Sold

  2. #22
    Join Date
    Oct 2001
    Location
    Granby, Missouri, USA
    Posts
    3,081

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    Check with this guy for repairing your instrument cluster:

    https://drspeedometer.com/

    Casey
    1995 K1500 Tahoe 2 door, 6.5LTD, 4L80E, NP241, 3.42's, 285/75R16 BFG K02's; 1997 506 block; Kennedy OPS harness, gauges, Quick Heat plugs, and TD-Max chip; Dtech FSD on FSD Cooler; vacuum pump deleted, HX35 turbo, Turbo Master, 3.5" Kennedy exhaust, F code intake; dual t/stats, HO water pump, Champion radiator; Racor fuel filter

  3. #23
    Join Date
    Jul 2014
    Location
    El Dorado
    Posts
    22

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    Quote Originally Posted by DmaxMaverick View Post
    Yes, if the tach has issues, you repair/replace the entire IPC. Your description sounds like a failing alternator. If/when you replace it, measure the pulley before/after. Parts suppliers get it wrong often enough to be an issue. If you get the wrong size, just swap them, and keep the original. You'll need a 1/2" impact driver or a solid wrench and a BFH to R/R.
    I had the IPC overhauled but the problem remains. Since the tranny is OK, the tach has been overhauled, this seems to leave the alternator. Is it possible to replace the sensor in the alternator that generates the signal for the tach, or do I need to put a new alternator in there?

    Thanks

  4. #24
    Join Date
    Feb 2000
    Location
    Montana
    Posts
    11,382

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    Alternators aren't that expensive. I'd replace it... But, before you do, I'd remove the original alternator's pulley, and replace the one on the new alternator. These pulleys are specific to the 6.5L diesel - for tach accuracy. The 6.5L diesel alternator pulley should measure 67mm peak to peak when measuring across the pulley's peaks and valleys.

    The last alternator I replaced had a 59mm pulley... That produced about a 500-rpm error. What seems to happen is that the original bad alternator on a 6.5 would be traded in for an auto parts store replacement, not knowing the pulley was unique. Since more of these alternators (and smaller pulleys) were used for a gas engine application, that's what you'll likely get as a replacement.

  5. #25
    Join Date
    Jul 2014
    Location
    El Dorado
    Posts
    22

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    Thank you very much. I agree with all that you've said. I also concluded, based on a few Internet searches, that that little pulse generator gizmo in the alternator cannot be replaced separately, so I'll just R & R the whole unit. We'll pay particular attention to the pulley.

    Will let you know.

  6. #26
    Join Date
    Jan 2001
    Location
    Knoxville,Tennessee
    Posts
    2,639

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    If you can find a local re-builder for your original alternator you'll have a much better end product and the correct pulley.
    "The Constitution is not an instrument for the government to restrain the people, it is an instrument for the people to restrain the government."
    -Patrick Henry


    A5150nut
    2006 K3500 D/A
    94 6.5 4x4 5spd Sold

  7. #27
    Join Date
    Jul 2014
    Location
    El Dorado
    Posts
    22

    Default

    Replaced alternator, I'm told problem is fixed. Have a new IPC and alternator now.

    I very much appreciate the advice. This '99 Suburban w/6.5 TD has 66K on the clock, and I intend to keep it forever. You've helped me toward this goal.


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