Olds 403 Alternator Issues

Discussion in 'Sparky's corner' started by Shurt24, Apr 9, 2019.

  1. Shurt24

    Shurt24 TheRivKid

    Crossbreed here, 1977 Riviera with the Olds 403. I’m having alternator issues.

    I have added another battery and a high output alternator to the car, (had it built by a local shop), after killing a few OEM Replacement alternators from O’Reillys, and since it was installed, I’ve had problems.

    With the OEM replacement, everything works !except! it squeals to high heavens when under a heavy load. (Aftermarket stereo, amplifier, etc) AND my generator light stays ON.

    With the H.O. alternator, the gas gauge doesn’t work, it doesn’t seem that the batteries are being charged, but it keeps the car running, and the generator light is OFF. (As it should be)

    At first, I thought it was a hot-start issue, because it would start once, run for a bit, and then after I turn it off, I turn the key and get a half turn and then clicks. The starter is relatively new, though.

    When I jump start the car, it doesn’t require “charging time,” the starter whirls, and it fires right up.

    Is it possible that I’ve killed the 2 batteries with all of my tinkering? But when I think about that, I remember not having these issues with the other alternator, just the squealing, and the generator light.
     
  2. telriv

    telriv Founders Club Member

    CLEAN THE BATTERY CABLES & POSTS!!!!
     
  3. Shurt24

    Shurt24 TheRivKid

    They’re surprisingly not corroded, but i’ll definitely start there and give them a scrub. Thank you.
     
  4. gstewart

    gstewart Well-Known Member

    sounds like your stereo + amp are drawing too much juice. U need to check the amps being drawn with lights, stereo, amp, etc., to see if the amp draw exceeds the alternator max amperage. I do believe I have heard alternator whine when the draw is too much.
     
  5. BRUCE ROE

    BRUCE ROE Well-Known Member

    I struggled with my 77 403, and many other late 70s Olds small blocks, with
    slipping alternators. But apparently the General did too, and finally did
    something about it. The sketch shows the 70s arrangement at the bottom,
    and the 81 and later arrangement at the top. For 81 A LARGER DIA pulley
    at the water pump drives the alt. With no third pulley, this belt has MORE
    DEGREES of wrap around the pulleys, better traction. The LARGER DIA
    means less pull on the belt to make it slip, and with the alt speed stepped
    up, the alt does not need as much torque to generate the same amount of
    power. If your alt has a smallish pulley (no they are NOT all the same), a
    larger one (say, 1/4 inch larger dia) may be used without loss of alt rpm.

    I finally converted all 5 Olds engines to this setup, what a relief. How, the
    last decade of Olds small blocks have the parts. The accessories stay put,
    but the crank and water pump pulleys change. Oh, and the power steering
    pump goes from 2 grooves to one. I just grab that from the later car, but
    there is ONE PROBLEM. This pump has a metric pressure hose fitting,
    but your 70s steering box has an English fitting. FORTUNATELY the
    metric fitting UNSCREWS from the late pump, and your English fitting
    from your old pump goes right in, use your original hose.

    Alt wiring, more later. Bruce Roe
     

    Attached Files:

  6. Shurt24

    Shurt24 TheRivKid

    Bruce, thank you. I actually took the (160A) alternator back to the shop that built it, and he replaced the larger pulley with a smaller pulley. His reasoning being that my idle wasn’t fast enough for the alternator to perform with a larger one.

    I’m going to study those diagrams and dig in.

    Thank you, again.

    GStewart, thank you. It’s a 160A. But you’re right, I’ve never actually checked to see. I was told “160A” oughta be plenty. My fault.
     
  7. Shurt24

    Shurt24 TheRivKid

    Went a bought a new control alternator, just in case. (OEM replacement 63A). It’s doing the same thing the other 63A did. (I’m not suprised) squeals like he//. (I unhooked any accessories). The gas gauge works again. I don’t get it.

    Why would the aftermarket alternator:
    A) keep the car running, but not charge the batteries.
    B) not allow my gas gauge to work.?
    C) turn my alternator dash light OFF.

    The OEM alternators:
    A) charge the batteries.
    B) gas gauge works.
    C) squeals like he//.
    D) keep the alternator dash light ON.
     
  8. stellar

    stellar Well-Known Member

    Turn key to run position, do not start the car. Do you have an alternator light on on the dash in this position?
     
  9. stellar

    stellar Well-Known Member

    Ar first look it seems you have a blown charge indicator fuse. OEM alt (A) alternator is working (C) Probably belt squeal - multiple - Alternator overloaded (power demand too high), bad belt , wrong belt width, loose belt. (D) Indicator light on- Alt working with an open charge lite circuit - probably fuse. (B) not sure unless fuel gauge works off of same circuit as charge indicator lite. Aftermarket 160 amp. (A) Alt not working. When batteries get low enough car will stop running. (C)Blown charge fuse alt not working. (B) Alt not working and is on same circuit as charge lite. Aftermarket alt may have a 1 wire regulator in it. Tell me which alt is on there now, and I will try to give you the fastest and easiest way to test.
     
  10. stellar

    stellar Well-Known Member

    Did you ever find the problem?
     

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