1940 coupe temp sender and gage

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flathead 53

Well-known member
I changed out my temp gage for a new nos one,and changed the sender in the head,gage goes all the way to hot after ten minutes, checked at the heads with a inferred gun temp shows 160/165 deg ,running dole nos 160 deg thermostats, can't figure out the problem,the engine has only one temp sender single pole on driver side on my 40 coupe. my 53 f-100 has two senders a two pole on pass side with a wire going to driver side sender and that works fine, maybe it should have two senders? any ideas ?:mad:
 
Kinda strange, these same questions come up almost every day! The single is the correct one for gauge to read a temp, the double one is an on/off switch set are around 204 deg.
You can test the gauge with a 1.5v D battery. With the gauge disconnected from the car wiring, connect a D battery across the gauge post, it should read ~1/2 scale. Connect two D batteries in series for 3v and test again, should read ~Full scale.
 

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flathead 53 said:
I changed out my temp gage for a new nos one,and changed the sender in the head,gage goes all the way to hot after ten minutes, checked at the heads with a inferred gun temp shows 160/165 deg ,running dole nos 160 deg thermostats, can't figure out the problem,the engine has only one temp sender single pole on driver side on my 40 coupe. my 53 f-100 has two senders a two pole on pass side with a wire going to driver side sender and that works fine, maybe it should have two senders? any ideas ?:mad:
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All too often those "NOS" gauges in the boxes are the old ones that the service guy put back in the box. From personal experience I have seen this a lot. I had, back in the 1970's, a box with over 200 "NOS" gauges. Turns out they were all the used gauges, never returned to Ford for credit.

My guess is that's what you have. I might suggest you put the old dash gauge back in and see what change, if any occurs. If that doesn't do it, put the "NOS" back in and swap the sending unit. Of course do one thing at a time.
 
problem solved, installed new gage old one was ok, installed a used temp sender that was bad also, took temp sender out of my 53 f-100 put it in the 40, temp gage now works great ,
 
LOL, that is what the shop manuel I have suggest for a test of the sender, change it and see what happens! Didn't think that was worth repeating, but guess in this case it would have worked.
 
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