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Thread: Earthing issues

  1. #1
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    Earthing issues

    Hi,
    Trying to iron out a few wiring issues on my 2a project.

    The first and largest issue is that it seems to want to earth through the throttle/accelerator cable (definitely not good at all).
    For context: negative earth 1971 2a diesel with 1980 series 3 engine.
    When I got the car, the battery was hooked up to earth to the side of the battery mount (so the chassis), and the starter motor is also earthed to the chassis.
    Am I correct in thinking that usually the batter earths to the block?

    The perplexing thing is before we stripped her down, she started and ran just fine, so I suspect it’s something to do with how I’ve hooked things up.
    When the key is set to the first click (ancillary) there doesn’t seem to be an issue, but when cranking the throttle cable heats up and smokes, and the engine seems to crank at quite a low speed.
    Would this imply the issue is to do with the starter motor wiring?

    Cheers

  2. #2
    JDNSW's Avatar
    JDNSW is online now RoverLord Silver Subscriber
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    Obviously you have poor connection between the engine block (starter) and the battery. The connections battery->chassis and starter -> chassis should be OK, but obviously there is a bad connection. This will be the starter to chassis, as the battery lead will not result in the throttle cable getting hot, with possible problems being - chassis connection not onto bare steel; starter connection not on to bare steel; chassis connection is not actually on the chassis, but is, for example, onto a bolted on bit such as the upright that has the stay to the firewall (steering box mount for LHD); tags on the ends of the lead either not clean or not properly soldered to the wire; wire not heavy enough.

    You can find where the issue is by checking the voltage drop across each joint when the starter is operated.
    John

    JDNSW
    1986 110 County 3.9 diesel
    1970 2a 109 2.25 petrol

  3. #3
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    Thanks heaps John,

    All sorted now,
    just need to fix the poor running issues I'm having now!

    Luca

  4. #4
    JDNSW's Avatar
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    Can you tell us what the issue you fixed was? Might help others seeking help in the future.
    John

    JDNSW
    1986 110 County 3.9 diesel
    1970 2a 109 2.25 petrol

  5. #5
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    Yes of course.

    whilst I'd made sure to keep the earth wire from the alternator to the chassis on bare steel when I painted the chassis (wire wheeled that bit) I hadn't payed any attention to the braided earth wire itself.
    Removed it and wire wheeled the whole thing until it was a nice shiny copper colour, this seemed to fix the issue. I assume it was so clogged and greased up that it was struggling to earth.
    There are still a few wiring issues I have to sort, but much more minor - just lights and things (also earth related I suspect!).

    Thanks heaps
    Luca

  6. #6
    JDNSW's Avatar
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    Note that I have found it necessary to run separate earth wires from the radiator support (has the headlights on it) to the battery and from the firewall to the chassis (fixed some instrument issues).
    John

    JDNSW
    1986 110 County 3.9 diesel
    1970 2a 109 2.25 petrol

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