185 temperature questions

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   I just replaced the temperature gauge on my 185 and got a reading at the left edge of the white region.  Question: does anyone know a proper test for the temperature sending unit?  Most likely, the thermostat is stuck open as this tractor has essentially been in barn storage for over 3 years.  I would like to eliminate the sending unit as the culprit before changing the thermostat.  I get 1.5 to 3 ohms resistance across the sending unit depending on temp; I have seen references to resistances in the 400 ohm range for AC sending units.  Any suggestions?

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briarpatch Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 02 Dec 2011 Location: Vichy, MO Points: 15	Post Options Post Reply Quote briarpatch Report Post Thanks(0) Quote Reply Topic: 185 temperature questions Posted: 02 Dec 2011 at 5:33am
	I just replaced the temperature gauge on my 185 and got a reading at the left edge of the white region. Question: does anyone know a proper test for the temperature sending unit? Most likely, the thermostat is stuck open as this tractor has essentially been in barn storage for over 3 years. I would like to eliminate the sending unit as the culprit before changing the thermostat. I get 1.5 to 3 ohms resistance across the sending unit depending on temp; I have seen references to resistances in the 400 ohm range for AC sending units. Any suggestions?

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DougS Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Joined: 03 Nov 2011 Location: Iowa Points: 2490	Post Options Post Reply Quote DougS Report Post Thanks(0) Quote Reply Posted: 02 Dec 2011 at 7:40am
	It should vary by temp, but not a mere few ohms. I just looked at a random one and it varied several thousand ohms with a temperature span of 100(C) degrees. It almost looks as it your sensor is shorted. Pull the wire at the sensor and substitute a resistor. Try 1000 ohms. Try another value - perhaps 5000 ohms. If you get readings somewhere in the gauge, replace the sensor.

briarpatch Members Profile Send Private Message Find Members Posts Add to Buddy List Bronze Level Joined: 02 Dec 2011 Location: Vichy, MO Points: 15	Post Options Post Reply Quote briarpatch Report Post Thanks(0) Quote Reply Posted: 07 Dec 2011 at 4:37am
	Doug is right. A new temperature sending unit will read from 100 ohms (very hot) up to 800+ ohms (very cold). Checking the electric sending unit will pretty well tell you if the gauge is getting a proper signal or else the thermostat is stuck. Thanks for your data!