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86 CJ7 weird sound / need help

Discussion in 'CJ' started by BAJA RDY, Aug 2, 2020.

  1. Aug 2, 2020 at 8:03 PM
    #1
    BAJA RDY

    BAJA RDY [OP] New Member

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    I just picked up the 86 cj7 with a auto and a 4.2 carb. When it’s in neutral and you rev the motor up it’s fine. Put it in drive and start to drive it’s fine. As soon as it gets a load on it it makes a rod knock sound. Like to drive it onto a car trailer.

    Flex plate?
    Tranny?
    Transfer?
    Any ideas?

    18A2610E-57A5-4256-AD1E-8D8CB80661D9.jpg
     
  2. Aug 3, 2020 at 4:32 PM
    #2
    Jim Beam

    Jim Beam Well-Known Member

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    Fuel Injection, Dana 44s, T18, 4.10s w/lockers
    O.K., so when under load, is it like an ignition miss? need more description on that rod knock sound.
     
  3. Aug 5, 2020 at 2:24 PM
    #3
    BAJA RDY

    BAJA RDY [OP] New Member

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    No. It’s like a rod knock. Rpm related too. Only under load.
     
  4. Aug 5, 2020 at 2:45 PM
    #4
    Jim Beam

    Jim Beam Well-Known Member

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    Find out the close proximity of just where it is. Like by using one of those automotive stethescopes or use the end of a screwdriver with the handle against your ear. Do all the testing you can before having to pull the pan. I once pulled all the rod caps off just to find out they were in great shape. The noise turned out to be a clogged lifter. Fixed that with some Rislone.
     
    aggrex and LYFZGOOD like this.
  5. Aug 26, 2020 at 7:14 PM
    #5
    jeepnik

    jeepnik Member

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    Sure it isn't a ping. That usually happens under load. A rod knock is usually all the time.
     
  6. Aug 27, 2020 at 5:28 AM
    #6
    Silentrunning

    Silentrunning Member

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    I would check the timing and the vacuum advance on the distributor.
     
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