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308 Water Temp Gauge Expert Needed!!!!

Discussion in '308/328' started by seschroeder, May 13, 2010.

  1. seschroeder

    seschroeder Formula Junior

    Apr 25, 2002
    251
    Alexandria, VA
    Full Name:
    Steve Schroeder
    Gentlemen:
    For approximately six months now I have been dealing with an apparent overheating problem. I say apparent because I do not believe the car is actually overheating. It is not losing water, no oil in the water nor water in the oil and temp confirmed with a IR temp gun (nothing above 180 F). Temp gauges reads approximately 225 degrees F.
    Today I changed what I thought was the temp probe in the valley for the engine behind the oil filter. With the probe out and the ground disconnected the temp gauge did not work. After putting the bloody thing back together I found I had left the single wire to the probe disconnected. The gauge worked, can this be right??? Does the gauge get its input from the probe in the valley or from the probe just below the thermostat housing?? The disgrams on the Ricambi web site do not show this probe.
    Thanks in advance.
     
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  3. PT 328

    PT 328 F1 Rookie
    Silver Subscribed

    May 1, 2005
    3,481
    I had a problem with my gauge reading higher than the actual temp. I pulled the gauge, cleaned the contacts, put it back together and all was well again.
     
  4. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,480
    Austin TX
    Full Name:
    Brian Crall
    #3 Rifledriver, May 13, 2010
    Last edited: May 13, 2010
    The sender you mention is for the oil pressure light.


    The sender you are looking for is on the coolant crossover pipe between the cylinder heads under the center of the plenum chamber.
     
  5. miketuason

    miketuason F1 World Champ
    Silver Subscribed Owner

    Feb 24, 2006
    14,525
    Cerritos, CA.
    Full Name:
    Mike
    +1 and if you pull that wire and ground it, your temp gauge should read MAX
     
  6. seschroeder

    seschroeder Formula Junior

    Apr 25, 2002
    251
    Alexandria, VA
    Full Name:
    Steve Schroeder
    My fault, bad description. I did change the temp probe in the crossover pipe. What I do not understand is why the gauge works with the ground wire connected but the wire to the probe itself disconnected.
     
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  8. DavidB_SD

    DavidB_SD Rookie

    Sep 7, 2008
    45
    San Diego, CA
    Full Name:
    David B
    The water temp sender is basically a variable resistor to ground. As the sender temperature rises, the resistance value gets smaller. Touching the wire to ground, instead of to the sender, simulates an overheating condition as far as the gauge is concerned and it should go to max temp (as Mike pointed out). An open (wire connected to nothing) should cause the gauge to stay at the minimum temp reading.

    When you say the gauge worked with the wire disconnected, what exactly do you mean? When it did this, was the metal connector touching the block? What was the gauge reading?

    -David
     
  9. seschroeder

    seschroeder Formula Junior

    Apr 25, 2002
    251
    Alexandria, VA
    Full Name:
    Steve Schroeder
    Problem appears to be solved. I replaced the connector to the probe and cleaned the spade connector for the ground wire. I also replaced the ground wire connector and ran an additional wire to ground. Ran the car this AM and it never got above 108-185 F. I'm happy now!!!
     

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