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  1. #1

    Join Date
    Dec 2005

    Default 8N wont start

    Hi , for a long time I have had to jiggle the shifter when pressing the start " BUTTON " to get the old girl to start, now I can jiggle til I fall off to no avail. Is there a way to bypass the interlock ? This old girl has been a good tractor and aside from changing all the rubber I have only changed fluids and such, not rebuilt or anything. It is 12 volts. I need to use it once more before putting it in the shed for the winter and fixing it properly. Thanks Bruce

  2. #2
    Veteran Member
    Join Date
    Oct 2004
    Lecompton, Kansas
    2016 Mahindra 1533 Shuttle AgKing 2840 shuttle shift

    Default Re: 8N wont start

    Bruce, it sounds like your start button or solenoid have failed. Most likely the start button, if jiggling the shifter made it work, I don't believe that anything that old had a safety interlock of any kind. Maybe the wires on the bottom of the start button are dirty, corroded, or loose. If you are sure that the tractor is in neutral, you can jump out the solenoid with a screwdriver and it should start. Trace the wire from the starter (the big one) it will go back to the solenoid. Jump from the right hand side of the solenoid big wire to the small wire terminal. This will engage the starter motor if the battery is up to full charge. (Made sure the ignition switch is in the "on" position. Choke if necessary and it should fire right up.

  3. #3
    Old Timer Soundguy's Avatar
    Join Date
    Mar 2002
    Central florida
    ym1700, NH7610S, Ford 8N, 2N, NAA, 660, 850 x2, 541, 950, 941D, 951, 2000, 3000, 4000, 4600, 5000, 740, IH 'C' 'H', CUB, John Deere 'B', allis 'G', case VAC

    Default Re: 8N wont start

    The Ford N series DID indeed have safety interlocked start buttons.. ( 2 types ) the very earlies 9n did not have this feature. The later 9n and all 2n had a mechanical linkage / tranny neutral interlocked switch that activated a large hi-current switch between the battery and the starter. I fthe shifter was not in neutral, the starter button could not be pressed enough to move the mechanical linkage to press the big starter switch at the front of the steering column.. The 8n , naa, and hundred series used a grounding tranny neutral interlocked switch.. the switch merely provided ground for the 'internally hot' 3 wire oem solenoid. thus completing the circuit. if the shifter was not in neutral, the button could not be pressed far enough to complete the circuit.

    If jiggling the shifter made the start button work, My guess is a worn shifter pattern on the underside of the tranny shifter cover.. that is also where the big thumb interlocked button is attached with a locking tab and retainer.. The shifter pattern gets so much wear thatt he interlock plate is not moving sufficiently to unlock the start button.

    Some have had luck with brazing the worn points up.. other repalce with working salvage.

    To test the solenoid and starter, you can remove the single wire from the base of the switch. if this wire is then touched to frame (ground ).. it should allow the solenoid to energize.. so make sure you are in neutral before defeating this safety interlock feature that ford had in place since the late 30's

    An ohm meter can then be used on the thumb switch.. you may be able to shif the tranny almost in or out of a gear and get the switch to work, thus confirming the worn interlock shift pattern.

    The I&T FO-4 manual has diagrams and pictures of this part.

    If you do remove the shifter cover.. do so slowly.. there is a single spring and detent ball that will be held under a little pressure.. make sure you lift slowly and capture the parts and don't let them fly off intot he shop or into the xmission..

    Also.. as a note to Bill.. the ford oem 3 terminal solenoid alread has one side of the coil tied to the incoming starter wire thus making it internall hot.. therefore shorting the hot line fromthe battery to the small 3rd line does absolutely would be applying power to both sides of the solenoid coil... that small 3rd terminal needs -ground-


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