Topic: Temperature gauge


Carcheologist    -- 06-20-2021 @ 4:07 PM
  Where should the temp gauge needle be pointing when the ignition switch is turned OFF - toward COLD or HOT?


sarahcecelia    -- 06-20-2021 @ 5:41 PM
  Toward COLD!!

Regards, Steve Lee


40 Coupe    -- 06-21-2021 @ 7:27 AM
  Toward Hot. When you turn the ignition to ON the pointer will move to cold and then slowly move with the engine temperature.


TomO    -- 06-21-2021 @ 7:42 AM
  40 Coupe is correct.

Why do you ask?

Tom


Carcheologist    -- 06-21-2021 @ 7:53 AM
  I've been trying to get the gauge to read correctly and suspect my sending unit is bad. The needle moves to full HOT when the ignition switch is turned to OFF, then moves way past the cold mark when turned ON. It doesn't move toward HOT as the temperature increases. Looks like my sender is bad and needs replacing. Any thoughts?


RAK402    -- 06-21-2021 @ 10:04 PM
  It seems to me there is a test for the dash unit, using a gas gauge sending unit in place of the temp sending unit, outlined in the 1938 to 1940 Complete service bulletin books.

Someone outlined it here on the forums, and once in the dim, dark past, I did it and it worked (my repro sending units were not made correctly).

Update! I found the test: Operation 10883-A (page 314 of the service bulletin book).

I can scan it and post it for you, if that will help.

This message was edited by RAK402 on 6-21-21 @ 10:19 PM


Carcheologist    -- 06-22-2021 @ 8:01 AM
  RAK402,
Thanks for the tip! I have the service bulletin book and will check it out.



TomO    -- 06-22-2021 @ 8:32 AM
  It sounds like your dash unit is working correctly. Your problem could be in the sending unit or the wiring. Do a quick check of the wiring by connecting a jumper from the sending unit with 1 terminal to ground and then turn on the ignition switch. The needle on the gauge should move towards HOT. The fuel sending unit test will check out thhe gauge further.

The new replacement sending units do not work the same as the original units, so I would look for an original King-Seeley unit. Your best bet for one of those is another Ford guy or swap meets.

Tom


cub 45    -- 06-22-2021 @ 10:48 AM
  what would happen if you reverse the wires on the gauge ?


Carcheologist    -- 06-22-2021 @ 11:04 AM
  Here's an update to my testing efforts:

Swapped out several old sending units, with various states of unsatisfactory results. With one of them, the needle retreats halfway towards COLD when the ignition switch is turned on and then rapidly advances into the HOT range as the temperature increases. After registering well into the HOT position on the gauge after driving for a while, the needle falls back to the COLD position and stays there until the car cools completely down.

Others show the needle to move quickly past the COLD mark as soon as the switch is flipped on and then after a short time of driving, it advances to full HOT!
It seems the old sending units are giving me various readings, but I don't think the gauge is at fault; at least not yet.

I have ordered a new sending unit from Third Generation Automotive and we'll see how that plays out.


RAK402    -- 06-23-2021 @ 10:39 AM
  I agree with Tom O about trying to locate an N.O.S. sending unit.

I had nothing but trouble with the new/repro units.


Carcheologist    -- 06-25-2021 @ 6:38 PM
  Installed a new Dennis Carpenter sending unit. With the engine COLD, flipped on the ignition switch and the needle moved almost all the way to the COLD side of the gauge (but not quite), and then moved rapidly to the NORMAL mark after a short period of running. After engine has warmed to operating temperature, needle sits about halfway between NORMAL and HOT. Not what I had hoped for, but better than the old original ones I had been using.

(*I should mention that when testing all the sending units, I did not run any themostats and am using Water Wetter with plain water as a coolant.)


o2bnkc    -- 07-20-2021 @ 6:31 PM
  I replaced both of mine, using 50/50 and Water Wetter, and my gauge usually comes up to halfway between normal and hot, also.

A Proud Navy Vet


sarahcecelia    -- 07-25-2021 @ 9:50 AM
  I'm so sorry! What was I thinking?? I think I had a brain Far##t-All Fords go to HOT when the ignition is off! Then when the ignition is turned on, it goes to COLD, and then slowly rises to the temp the motor is warmed too!

Regards, Steve Lee


sarahcecelia    -- 07-26-2021 @ 7:56 AM
  SO SORRY!! I had a brain f**t! Ignitition off- HOT!! Ignition on- it will slowly go to COLD!!

Regards, Steve Lee


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