| 37RAGTOPMAN | -- 02-22-2016 @ 3:57 PM |
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HI I was wondering how to test the temp senders in a 1940-1948 FORD, 1 has one wire, the other has 2 connections, these are out of the car, using a ohm meter, what should they read, many thanks,, RAGTOPMAN 1937
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| TomO | -- 02-22-2016 @ 4:33 PM |
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The one with 2 connections is just a high temperature switch. It opens when the coolant temperature is above boiling. Your ohm meter should read zero ohms. The one with one terminal is a bi-metal strip with a heating coil wound around it. The heating coil balances the current in the circuit with the temp gauge through a set of contact points. The gap between the contact points varies with the coolant temperature. It should read less than 1 ohm on your ohm meter. It should be connected to the gauge and a battery in order to test it. Tom
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| Drbrown | -- 02-22-2016 @ 6:25 PM |
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The Ford Service Manual and Service Bulletins describe a testing procedure as noted above. Just to provide some information, my personal experience with the two stock sensors is that my two-terminal sensor was giving false readings at the stock dash gauge during engine warm-up. The stock gauge would rise to the top "H" and then fall-back to a normal reading at mid-gauge. My independent mechanical temp gauge in the left head would indicate normal warm-up and running temp. Changing thermostats did not correct this behavior. The radiator is relatively new, the coolant is clean, and there's no leakage in the system. So keeping the single-terminal stock sensor active, I by-passed wiring of the two-terminal sensor and now the stock dash gauge reads and behaves correctly. Others on the forums have reported the same problem. As long as I have the mechanical gauge working in the left head I don't see the point of replacing the defective stock two-terminal sensor. This message was edited by Drbrown on 2-22-16 @ 6:30 PM
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