[SOLVED] - Hot positive battery lead on 74 260 z | The Z Club of Great Britain
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[SOLVED] Hot positive battery lead on 74 260 z

Discussion in 'S30 (240Z,260Z,280Z) Electrical' started by mrzed, Apr 29, 2017.

  1. mrzed

    mrzed Forum User

    Is there any common reason the positive battery lead gets hot whilst cranking to start?
    It gets that hot it's almost melting the plastic coating coating .
    I have been having starting issues and when pounding the battery for a few minutes the cable and the terminal on the positive too hot to touch
    Would replacing the battery cables solve this or could something else be causing this?
    They are old original ones.
     
  2. yellowz

    yellowz
    Z Club Member

    I just know someone is going to say this better. I'd get a stronger cable that is big enough to take the current running through it safely.
     
  3. mrzed

    mrzed Forum User

    Yeah I think the best bet is start with fresh cables ,
    This could be the reason when it was running before the starting problems I'm having ,
    It would be running fine then it would start to miss like as if I was switching the ignition on and off quickly then some backfiring and then eventually cut out .
    I thought it was fuel related but fuel is getting through
    Could be a dodgy coil too I'm thinking because there is not a really good spark at the plugs
    I'm running the old points system at the moment but I have a 12-80 280zx dizzy I'm wanting to fit but need a 280zx base clamp and timing plate .
    I have a new 280zx coil and rotor arm also
    Maybe best to try and get the new leads and try to get a dizzy clamp then start from there
    Instead of wasting time with old tech.
     
  4. franky

    franky
    Z Club Member

    I'd say its a poor earth.
     
  5. jonbills

    jonbills
    ZClub Administrator
    Staff Member Committee Member

    Are you talking about the +ve to the starter? I think it is too thin for sustained cranking.
     
  6. mrzed

    mrzed Forum User

    I'm talking about the black positive cable that goes on the battery jon
     
  7. jonbills

    jonbills
    ZClub Administrator
    Staff Member Committee Member



    I'd agree with Franky then
     
  8. mrzed

    mrzed Forum User

    Any suggestions on where to start looking for a bad earth?
    Is that like the terminals on the starter motor ?
     
  9. jonbills

    jonbills
    ZClub Administrator
    Staff Member Committee Member

    The battery terminals, the starter terminals and the big earth strap on the top bolt connecting the block and bellhousing.
     
  10. mrzed

    mrzed Forum User

    The big earth strap could be be the culprit, I will investigate,cheers Jon
     
  11. Wyn

    Wyn
    Z Club Member

    What I was thinking.
    You could always add another fresh earth from the block to the chassis somewhere, as that isn't going to hurt either
     
  12. mrzed

    mrzed Forum User

    Sorry franky, I never thanked you too .
    Right been in the garage to check connections on the starter , cleaned them up, took the - terminal off cleaned that too .
    Where the - terminal is bolted to the starter motor bolt ,should there be a braided wire strap going to the bodywork or chassis too ?
    There isn't one
     
  13. tel240z

    tel240z
    Z Club Member

    No earth strap from starter should be from the battery to the bulkhead, i suspect your starter motor may be drawing too much current unless your cranking it over for minutes at a time :unsure:
     
  14. mrzed

    mrzed Forum User

    Put a new earring strap on today from battery to bulkhead and a new condenser and seems to have solved my starting and running issues ,also the positive terminal is cool,
    I would like to thank you all again for your help.
    Now got to put it in for an mot and hopefully I will be enjoying my car again sometime soon
     

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