| Jules51 | -- 05-17-2020 @ 9:30 AM |
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Which side, Driver - Passenger - does the single prong temperature sending unit go? Part # 8A-10884. I understand that this is the primary. If I have it reversed; double prong, #8A-10990, on Driver side, will this give me a incorrect reading on my temp gauge? Temp gauge reads Cold while driving but when I'm parked idling it moves to the center and once I start driving it falls back to Cold., with engine OFF, the needle moves to HOT, which is correct. Thermostats are good, IR temp reading of radiator is normal, temp gauge is ok, wiring is correct. What am I missing? Thanks Jules51
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| 51woodie | -- 05-17-2020 @ 10:12 AM |
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Not real familiar with the '51, but my'46 has the single contact on the passengers side, a connecting wire goes to one terminal of the double contact on the drivers side, and the temp gauge wire is connected to the other terminal. The single contact unit is what sends the temp signal to the gauge. The double contact sender is like an on/off switch, which opens when the temp on the drivers side gets too high, which causes the gauge to go to full hot.
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| JayChicago | -- 05-17-2020 @ 11:58 AM |
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Does not matter which side has the switch vs. the sensor/sender. When you say gauge is reading cold, do you mean it is at the bottom of the gauge scale, or do you just mean it is in the lower portion of the scale? If you have 160 degree thermostats, it may be reading correctly in the lower part of the gauge scale. Your symptom: "Temp gauge reads Cold while driving but when I'm parked idling it moves to the center and once I start driving it falls back to Cold." That makes me think of a thermostat remaining open, on the sensor side. Are you sure the thermostat is good? You said you read the temp of radiator with an IR thermometer, but did you read temps on the heads / hose fittings near the thermostats? You could do that and compare side to side. Another thought: the sender could be inaccurate, only moving the needle when engine temp gets warmer at idle.
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| Jules51 | -- 05-17-2020 @ 12:30 PM |
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Jay, thanks for your response. When I read the temp with the IR, I was getting an even reading of about 170-175 across the heads. Thermostats were replaced, 160 rating and appears to be functioning. The needle goes to the bottom of the C but I do get a little movement at stop lights, then back to C. Question: the wire from the main harness for the sender, I'm connected to the double on the driver side then using the x-over wire to the single head on the passenger side; refer to pic. Thanks Jules51
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| 51woodie | -- 05-17-2020 @ 3:45 PM |
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Here is the wiring diagram for the senders, and the routing for the connections. I guess it doesn't matter which side the senders are in, as long as they are connected as shown. This message was edited by 51woodie on 5-17-20 @ 3:47 PM
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| JayChicago | -- 05-17-2020 @ 8:01 PM |
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Jules Your two senders and the wire routing is correct. And your temperature readings on the heads seem right for 160 degree stats. I'm at a loss to understand why your gauge would behave that way. The only thing I can suggest is you try replacing the single pole temp sender with another to see what happens. That sender is the one that varies with temperature to vary the gauge's needle position. Perhaps that sender is faulty. Perhaps it is providing a correct value at warm temp when engine idling, but then it incorrectly jumps all the way to cold when the engine cools slightly as you drive. (If that sender is a new aftermarket sender, replace it anyway. Electrical items like this can sometimes be bad right out the box)
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| Jules51 | -- 05-18-2020 @ 5:02 AM |
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Thanks for the additional information and diagram, this will help. Thanks Jules51
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| TomO | -- 05-18-2020 @ 8:11 AM |
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Jules51, the single terminal sender is supposed to indicate the temperature and the double contact sender is just a overheating switch that opens when the engine is overheating. You have yours wired correctly. T Your single terminal sender is probably one of the recent aftermarket types. They seem to fail in the manner that you describe, reading low and slow to react to temperature changes. The best ones have KS stamped on the side. These are the original King Seeley units and are becoming very hard to find. Change yours with a new one or a good used one with the KS stamped on the side. Look for a replacement at swap meets. Tom
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| Jules51 | -- 05-18-2020 @ 1:39 PM |
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Tom, thanks for the information. I've learned something today, the KS units. I've searched my spare parts and DID find a KS unit, stamped a circled KS and has the number 224 stamped on the opposite side. It's clean. Is there a way to test these units? Thanks Jules51
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| Jules51 | -- 05-18-2020 @ 1:44 PM |
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Tom, an update: I have the Thermal Unit also, same KS stamp but has the # 217 stamped. Thanks Jules51
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| TomO | -- 05-19-2020 @ 12:06 PM |
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Jules51, The best test requires a spare temp gauge, 6 volt battery, a candy thermometer. and a pan of water. Connect the -6V to the gauge Connect the gauge to the sending unit Connect the + 6v to the case of the sending unit Heat the water to approximately 160 degrees Immerse the sensing end of the sending unit it the hot water and watch the gauge. It should read near the center of the scale. If you don't have a spare gauge, you could also use a jumper wire from the wire that goes from the sending unit to the gauge and use a jumper from the engine to the case of the sending unit. The last one that I tested, I used my ohm meter to check that the contact points were closed and making good contact. I heated the water to boiling, immersed the sending unit in the boiling water and waited until the gauge read HOT, then I removed the heat source and watched the gauge as the water cooled, comparing the gauge readings with the thermometer. Tom
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| Jules51 | -- 05-19-2020 @ 6:36 PM |
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Thanks Tom for the testing procedure. Thanks Jules51
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| Jules51 | -- 05-22-2020 @ 5:26 AM |
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Tom, an update: I installed the 2 KS units, taking a chance without testing. I'm assuming, need to be sure, the functioning of sending units: When the car is off, the gauge is position at "H", once the car is switch on the temp gauge goes from "H" to "C", assuming this is correct. After switching to the KS units I have the reverse. Car is switch on the gauge stays at "H" and as the engine warms it moves towards center of the temp gauge. I've ordered a new after market sending unit just in case. Wire from harness to unit is connected to the short prong and x-over is connected to the taller prong, reversing had no change. One last point. I applied a non-tape thread sealant to each unit, not the tape brand as before. Thanks Jules51
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| TomO | -- 05-22-2020 @ 7:27 AM |
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Jules51, that operation has me stumped. It sounds like you have a sending unit from a 1936-1938 Lincoln Zephyr, but those sending units required a reducing bushing in the head port to fit. The gauge should be at hot when the engine is off and go to engine temperature when the ignition switch is on. The way that the sensing works is that when the engine is cold, more current flows through the circuit forcing the gauge needle to move towards cold. As the coolant temperature rises, less current flows through the circuit allowing the gauge needle to move towards hot. My car is still in the body shop to repair the damage that wwas done on the way to Auburn last year, so I cannot check the series number stamped on those. I do not recommend that you use any thread sealant on the sending units for coolant or oil pressure. They need a good ground to operate correctly. Tom
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| sarahcecelia | -- 05-22-2020 @ 9:45 AM |
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It doesn't matter what side either is on. Some literature I've seen, shows the double terminal one on the right, and some shows it on the left. The single terminal one reads temperature, the double terminal reads Over Temperature. (The motor is over heating!) Regards, Steve Lee
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| sarahcecelia | -- 05-22-2020 @ 9:59 AM |
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180 degrees should read in the middle or close to it ; 212 degrees is at the far right! Some gauges are off a little; ! (they read past the 212 mark ; the far right; when the key is off; so they in turn will read that much past the mid point when you are at, or near, 180 on the thermometer check. So the best way to find that out is to run the motor with the radiator cap off until it gets to temp with a candy thermometer in the radiator, to read it against your dash gauge. If the thermometer reads 180, or within 4-5 degrees before or past it, the gauge should read close to that mid point. If it does, you are "Good to Go!! Regards, Steve Lee
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| sarahcecelia | -- 05-22-2020 @ 10:15 AM |
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JayChicago- 160 thermostats open just before 160 by a few degrees, but these flat heads will still read real close to the midpoint of the gauge when fully warmed up, because they still hold a temp real close to the 180 with any thermostat! Why you say? Motors don't operate well at low temps,and weren't designed to; that is very inefficient; plus if the cold pistons and other parts don't expand to the tolerances that they were designed to operate at, oil circulaton is poor, and an engine needs to be hot enough to burn off the water, acids,etc, that are in the oil and formed at initial start up. Look at you r tail pipe on initial start up and watch the drops of water coming out!! Do you want that in your motor and oil? NO!! Regards, Steve Lee
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| sarahcecelia | -- 05-22-2020 @ 10:24 AM |
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That 'Correct Wiring " depends on what book you read, or who you talk to; and mechanically it makes no diference which sender is in which side! I had a friend who had new 1950 when I was 18, it had a double terminal on the driver's side, and my dad had a New 1949, and the double terminal was on the passenger side!! Regards, Steve Lee
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