temp gauge, 1940 La Salle 5219

[Rhino 21150]

The temp gauge in my Dads 40 is acting up. It has a new sender installed, at a horrific price. Now it reads zero when cold but rapidly goes off the top as the engine warms. The car is NOT overheating (thermometer says so).
What is the resistance of the sender? Ohms hot and ohms cold? What is the internal resistance of the gauge itself? What is the part number of the sender?
The sender was NOT installed with teflon tape! Ive seen that mistake too often.
This gauge did not work when my Dad got the car. The wiring has been worked on by previous owner(s). Is there a mistake in the wiring that could account for this?
If this car wasnt 360 miles away I could go look myself, so I need to fix this over the phone!

[Doug Houston]

First, get your father to move closer so you can work on the thing.

Second, It looks like the temp gauge is trying to work properly. I suspect that someone has sold him a 12 volt sending unit. I dont know the resistance of either the 6 volt unit nor the 12 volt. As with the fuel gauge, high resistance is high scale on the dash unit. If the engine unit has too much resistance, as with a 12 volt one, the dash unit will go off scale at normal temperature.

I bought a couple of those engine temp gage units from NAPA a few years ago for about $12,50  each. Maybe they still have some     ?

[Jack Hoffman #7042]

Ohm meter readings are:
COLD-130 ohms
Guage mid point-70 ohms
Hot-30 ohms.
These readings were from a temp. guage tester. A 12 volt sender is about 220 ohms cold.

[Rhino 21150]

Thanks folks. I will talk my Dad through this and let yall know what happens.