| 42wagon | -- 07-14-2012 @ 5:55 PM |
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I have a problem with the temperature reading in my 42 wagon. 1. When the ignition switch is off the temperature gage is all the way over to hot. 2. When I turn on the ignition switch and the engine is running the gage first drops down all the way to cold and then gradually goes all the way to hot as the engine warms up. 3. Checking with a laser heat gun both heads and the radiator are at 155 degrees. 4. All wiring is new. The gage and the sensors are original. 5. All other gages work correctly. How do I correct this problem? Ted
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| Old Henry | -- 07-14-2012 @ 6:58 PM |
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If the temperature sensor/sending unit on the right side of the engine is original it probably needs replaced. Mine did after 60 years. Don't worry about the left one, it's just an on-off switch that opens to send the gauge to max when too hot. Old Henry (The older I get, the better old looks.)
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| supereal | -- 07-14-2012 @ 8:15 PM |
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The single terminal sensor has a heating element in it to provide a bias reference. When that winding goes open, you will see the problem you have. The two terminal sensor is a bimetallic switch that opens at boiling temperature. Be sure to check all wires and connections, as well, because the gauge goes to the hot side if the circuit loses conductivity.
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| 42wagon | -- 07-15-2012 @ 4:15 AM |
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Supereal and Old Henry Thanks for the tips. I will try replacing the right sensor as that seems to be the most logical explanation of my problem. Ted
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| 42wagon | -- 07-15-2012 @ 6:32 AM |
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Supereal and Old Henry Cut the sensor in the left bank entirely out of the circuit and ran with only the sensor in the right bank. Temperature came up to normal and stayed there. So it turns out the sensor in the left bank (the off/one switch) is what is defective. Thanks again for your suggestions. Ted
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| Old Henry | -- 07-15-2012 @ 9:05 AM |
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Good you found the problem. I've not known a left sender to fail. Now I know. I believe the left sensor was Ford's way of monitoring the temperature of the left side of the engine (which is seperate from the right side for cooling) without having two seperate gauges. The actual temperature of the right side is measured since it is usually hotter than the left side which will usually be cooler than the right side. So, you might want to replace that left sender just to keep at least a "circuit breaker" in there. Old Henry (The older I get, the better old looks.) This message was edited by Old Henry on 7-15-12 @ 9:05 AM
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