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70's verses 80's sending units

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by mountainexplorer, Aug 7, 2004.

  1. mountainexplorer

    mountainexplorer 1/2 ton status

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    70\'s verses 80\'s sending units

    I have an '84 K5. The motor I put in it has sending units off a mid '70s. Is there a difference? I'm assuming there is cause temp and oil pressure gauges arent working right.
     
  2. R72K5

    R72K5 Banned

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    Re: 70\'s verses 80\'s sending units

    oil pressure changed ot electric in 76 or 77 i forget which year, sending unit should work if same size hole in tank, and if same size, 5/16" or 3/8" depending on if its for 2bbl or six cylinder, or for 4bbl

    good luck
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: 70\'s verses 80\'s sending units

    Oil and temp shouldn't be different, except of course the threads, which is no big issue.

    Now, have to make sure they are sending units, and not switches for idiot lights.
     
  4. mountainexplorer

    mountainexplorer 1/2 ton status

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    Re: 70\'s verses 80\'s sending units

    Well, all the gauges worked before in my '84 K5. Then I swapped motors, and used "mystery sending units" (ones I had saved from other motors... mainly mid-70s), and not a single guage works now. Oil pressure pegs over 60 at all times, temp goes up to like 125 degrees then stops, and no reading from the volts gauge.

    It's the same in my Suburban for temp. I swapped motors in it, and the temp gauge doesn't go over about 120 degrees, even when it has overheated and boiled over before.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: 70\'s verses 80\'s sending units

    When you disconnect the wires to the senders, do the gauges respond apropriately. I'd make sure the temp one pegs if you ground it out, and goes to 0 when disconnected.

    Oil sender must be grounded somehow, either in the wiring itself, or the sender is shot.

    Oddly enough, a "test" I came up with that seemed to indicate faulty oil pressure senders was to shake them. All the bad ones I've seen rattled when shaken, but new ones don't seem to. Not sure if thats just an old vs. new part coincidence or not. I'd not rely on it to be accurate, but if scrounging through parts, I'd probably take one that didn't rattle over one that did.
     
  6. mountainexplorer

    mountainexplorer 1/2 ton status

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    Re: 70\'s verses 80\'s sending units

    Are oil pressure sending units for gauges the big rounded ones rather than the small units?
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: 70\'s verses 80\'s sending units

    Yes.
     
  8. mountainexplorer

    mountainexplorer 1/2 ton status

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    Re: 70\'s verses 80\'s sending units

    My goof up then on the '84 K5. I think I stuck a little dinky sending unit in for oil pressure. It's probably for an idiot light. (I suppose I should light up at this time /forums/images/graemlins/doah.gif)
     

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