Info needed: Water temperature sending unit

[Tony Smith]

Originally Posted by Harlé Sylvain

Hello
Does someone know a modern replacement for the flathead ford temperature sending unit?

I use a 6v dash with a 12v reducer. I heard about ford truck units of the 70's?

Cheers

Harlé, I hope that the above discussion has not been too technical in English.

You will have noted the operation of the gauge. In the 6v system, the gauge at the dash shows "Hot" with no or low voltages and "cold" with full voltage. The sender on the engine has low resistance at cold temperatures, and increases resistance as the temperature climbs.

In 1956, Ford cars and Trucks changed to 12V electrical systems. The 12v gauge now worked in the opposite way. It showed "cold" at no or low voltage, and as the voltage increased moved to "Hot". The sender on the engine had a high resistance at cold temperatures, and the resistance lowered as the temperature increased.

Using a Ford 12v sender from post -'56 will only work with the corresponding gauge. The may look the same and have the same 3/8ths thread, but they will not correctly operate the 6v gauge, even with a voltage regulator.

EDIT The above applies to the temperature gauge system in use with US/Canadian/English/Australian Ford vehicles. I cannot confirm what temperature monitoring system was used on the French Flathead (SIMCA) or Matford Trucks, which I recall from an earlier thread was the source of your engine. In any respects, it is the 1940's Ford 6v gauge on the dash which you want to function correctly.