Temp probe

LanceB
LanceB Senior Contributor
edited November -1 in HUDSON
Ok, here's my next request for help. When I turn on the key the temp gage moves from the hot side all the way down to the cold side, so far so good. When the engine runs for a while I don't see the gage move at all. The head is hot along with the radiator hose. Is the sensor bad? Also an I having an issue with the thermostate opening?



Thanks, Lance

Comments

  • Unknown
    Unknown
    Hi Lance, you can check your dash gauge by putting the wire to the sender to a ground instead of the sender, it should flop all the way right then if it is good. Check your sender by putting it in water and heat the water ,get it HOT, can check water temp with cooking thermometer or such. When the sender is heated ,checkit with a multimeter from bulb end to terminal end ,the hotter it gets the more ohms resistance it will show. Check your water temp in the radiater also, some gauges don't register untill they get over 100 degrees or more, if it is getting hot enough it should be that you won't want to hold your hand on the radiater more than a few seconds, and the same thermometer will tell you exactly how hot it is and if it is getting up to the temp of the thermostat you have in it
  • Unknown
    Unknown
    Also when you ground the wire going to the guage, only ground long enough to get a reading. If you keep it grounded you will ruin the guage.
  • LanceB
    LanceB Senior Contributor
    Thanks guys I will try the wire from the sensor to see if the gage works. As for holding my hand on the radiator and hose, no I can't hold it there, too hot!
  • Unknown
    Unknown
    I'm not sure about all models, and I know things changed in 1950, but my 48 is setup to show what NASA calls "worst worst condition" if the gauge wires are disconnected or power fails. Fuel shows empty, and Temp shows hot. When you ground the temp gauge, it should float all the way to the left (cool). The fact that it shows hot before the key is turned, and cold afterwards tells me that the gauge is OK.



    The sensor is shorting to ground. I suspect you will see zero ohms when you try the boil test. I had the same problem.



    I think the sensor should show 0 ohms when cold, and about 50 ohms when at 212 degrees. At present, I have the wrong sensor in my car. When I start, it shows hot, and gradually goes down to 1/4 as the engine heats up. I have a reverse-thermister and need to get the right part.

    ]

    -Chris





    Gauges with power off



    http://zorak.chrishull.com/public/hudson2006/dashReassembledPart.JPG
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