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Discussion Starter · #1 ·
As some of my past posts show, I have fighting a pesky overheating problem. I have done everything that should eliminate this. 4-row radiator, correct fan placement, cowl, new thermostat, back flushed engine, etc... Still the needle on the temp gauge heads to the right. One thing I thought odd, if it's getting this hot why don't I ever get any overflow from the radiator? Today I ran the engine until the gauge read a little more than half way between C and H. Then very slowly released the cap and put a themometer in the radiator: 200 degrees. Shouldn't that read about 1/3 instead of 1/2+?

I am thinking that I may have the wrong temp sender unit because while my car was built in 66, the intake manifold is a rare C5AE-9425-M which was only used from Sept 64 thru Feb 65. Maybe the sender while normally correct for my car is incorrect for the manifold. Were there cars with gauges by Feb 65 or did they all still have lights? I am going to try the older sender and see if it helps.

Does it seem as though I'm on the right track? Has anybody else run into this situation?
 
G

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I think you're heading the right direction. You might buy a cheap mechanical guage & try it for a couple of days just to make sure. I've had the same problem a time or two.
 

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You are chasing a ghost. I had the same problem with Midlife when I first got it, and spent an inordinate amount of time and money chasing it down. I finally found the problem: not using a genuine Ford temperature sending unit. It dropped about 1/4 of the gauge reading from the non-Ford TSU. The TSU's are indicator gauges only, and you should not use the position of the needle to estimate your temperature without a calibration, which you just did.

Now for the kicker. The voltage to the gauge is controlled by the constant voltage regulator, located behind the dash. It has a little screw or post in the back that adjusts the output voltage, and hence the location of your oil, temp, and gas gauges. I adjusted mine so that the gas gauge read correct at 1/4 tank full, and lo and behold: the temperature gauge read 1/4 - 1/3 high! Previously, it was reading at the first high has mark. Temperature was the same.

Change your TSU and be happy.
 
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