valid Temp Sending unit test?
 

https://photos.imageevent.com/scott5.../IMG_37071.JPGI have tested all the gauges in the 1952 Crestline using the variable resistance method in the Shop manual. In essence using a resistor instead of the actual sending unit. Adjust the 50 ohm resistor until a reading of 1.5 volts is measured between the Volt input and the sending unit terminal should give a gauge reading of near the center of pointer travel. It does on Gas, Oil and Temp gauges. I connected the actual temp sender to the gauge and suspending it in a can of water that I heated to boiling. The gauge with no voltage sits at the high end of the range. as soon as the voltage is turned on to 12V with a Runtz regulator and the water room temperature the gauge drops to a couple pointer of widths below highest reading. As the water is heated up, the gauge steadily drops to max cold reading. Obviously the opposite of what I would expect a good setup to do. see in flaws to my test setup? I was thinking of buying an aftermarket sender unit. My thought was to use the dash gauge for one side of the engine and a mechanical gauge for the other. What readings should I expect with a good sending unit? Where does the gauge sit at startup and does it increase proportionately at the engine temp increases and where on the gauge is normal operation temperature. I get the impression that there is little difference between normal operation temp and boiling on the gauge. Thanks

Re: valid Temp Sending unit test?
 

Is that sender correct ??
From what i see it looks different from what i´m used to...
A sender can go from low to high or other way around...usually from low to high on temp since a broken wire will indicate hot and get drivers attention.
Wrong type sender and it will work as you state.

Re: valid Temp Sending unit test?
 

Are there any "shorts" in your test circuit the way it's hooked up?

Re: valid Temp Sending unit test?
 

No Shorts. Here is the sending unit that came from the head that had already been removed from the engine when I bought the car.

Re: valid Temp Sending unit test?
 

Well, it sure isn't original, so no telling what it is.

Re: valid Temp Sending unit test?
 

Looks like a stewart warner sender and that doesn´t work with the KS gauge.

Re: valid Temp Sending unit test?
 

My ‘50 has a gauge setup as you describe. When the mechanical side is at 180*, the electric side is at 3/4.....if that makes sense?....I’m unable to take pick till later today......Mark

Re: valid Temp Sending unit test?
 

Flathead ford8 That is a normal reading you should see for a 6v neg ground system

Re: valid Temp Sending unit test?
 

There was a thread a while back on how to take the stock temperature sending
unit apart and repair them.

Re: valid Temp Sending unit test?
 

One idea is that the sender I have is not a Ford King Seely sender or a replacement. I don't care about super accuracy. How do the replacement, resistance type senders work with the original gauge in terms of gauge reading. I should be able find a mark on the gauge that corresponds to 180 and 212 degrees. That is close enough for a warning. I understand that the replacement, resistance senders do work the same as the original but the must have a resistance vale that approximates the King Seely operation, especially in the normal operating range. Comments?

Re: valid Temp Sending unit test?
 

I do remember reading that repair thread. If the sender I have is an original, I can try that. but not sure my skills at taking it apart and resealing are good enough. Is it an original type?

Re: valid Temp Sending unit test?
 

Your sender pictured is most likely a stewart warner and not correct for the dash instruments which are King Sealey.

Re: valid Temp Sending unit test?
 

Yours is not an original, looks nothing like an original. Resistance sensors in general do not work will with the K-S gauges, but the temp sensors seem to work better than the other sensors. You need a resistance sensor that is scaled correctly for the gauge. I don't know the answer to which model number that is, but someone here on the Barn should know.

The full hot would be "zero" resistance on a sensor, but I don't know what the other end of the resistance range would be for cold.

Re: valid Temp Sending unit test?
 

Here's the posting on how to take apart and repair stock temp. sending unit. Those King/Sealy folks were pretty smart. Wonder what happened to their company?
If you have a Dremel tool you could easily cut one open and then use JB weld to re assemble. Open and scroll down. Very informative.
Read all of this.
https://www.fordbarn.com/forum/showt...ghlight=sender

Re: valid Temp Sending unit test?
 

Here is a picture of an original Ford sensor, what Scott has is a resistance sensor with the wrong calibration for an original Ford gauge.

Re: valid Temp Sending unit test?
 

Not only has the Stewart Warners the wrong range...they are backwards compared to ford...SW are either 240-33 or if older 120-16
Ford are if you put a ohm reading reference on them...i know i know...10-70

Re: valid Temp Sending unit test?
 

The king steely works on a pulse or on then off ,again ,both sender and receiver have a set of points and bi metal strip,one heats up and opens the other end does same,restance type will not work!lookin a old motor manual for description of how they work

Re: valid Temp Sending unit test?
 

They wont work correctly, but they will work. The resistance in the sensor will heat the coil in the gauge, it is just a different curve than the correct sensor.