Temp gauge Troubleshooting.

Discussion in '1955-1959' started by dorcutt, Nov 29, 2019.

  1. dorcutt

    dorcutt Member

    Joined:
    May 13, 2007
    Messages:
    169
    Location:
    Keep the truck in VT
    I must be getting really stupid in my old age as I get older as I have a temp indicator on my 57 that is driving me nuts.
    The original gauge either doesn’t work or it pegs out, I have three electrical senders for the system that all ohm out differently, I have purchased a new gauge and sensor from our host that pegs immediately out when connected externally. I have connected the gauges externally to the battery voltage with a ground on the gauge while being connected to the sensors with a good ground on the sensor, I don’t have thread tape on the one sensor in the engine. So I don’t quite know what I’m missing. I have put the sensors in hot, warm and cold water and can see the ohmic value change with temperature.
    Dose any one know what the temperature coefficient should be on the sensor? I have searched the old thread here and have not found it. An assumption I have made it the gauge dose take a full 12 volts that isn’t stepped down at all, that’s seems to be what the wiring diagrams say.
    What am I missing.

    Ps: Happy Thanksgiving.
     
  2. coilover

    coilover Member

    Joined:
    Mar 30, 2005
    Messages:
    2,466
    Location:
    Plano US
    There is one thing you can do if all else fails; use a 1955 gauge. Chevy didn't go to an electric sender till 1956 so the 55 still uses the capillary tube and the two are completely interchangeable. When you are doing the hot water test do you have a ground to the body of the gauge?
     
  3. dorcutt

    dorcutt Member

    Joined:
    May 13, 2007
    Messages:
    169
    Location:
    Keep the truck in VT
    So here is what I have done, I have three senders, a new one from our host, one from Napa and one that was originally in the truck. All three have different ohm readings through 100 degrees to 200 degrees. So I removed the gauge and hooked them up to the gauge externally and all three drive the gauge differently throughout the temperature ranges I noted above. So I selected the one that puts the needle at about halfway at 180 degrees. At 180 degrees the new sensor would only drive the needle to about 1/4 and the one from Napa would drive the needle to a little over 3/4 at 180.
    I had to ground both the sensor and the gauge itself to work correctly.
    Interestingly I had ordered both a new gauge and sensor from our host and when they were hooked up the new gauge would peg out. The new gauge actually peg out with all three sensors so I returned it. Not sure what was happening with it.
    Now I have to just run the engine and see what it gauge says.
     

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