Can anyone give me an ohm reading for their temp sender when the car is cold, 50-70 degrees. My temp gauge is not reading correctly and I have tried 2 different gauges and an aftermarket gauge. They all read about 140 when my temp gun reads about 185. I have another temp sender but it is not the same thread size and I get different readings from both. I have checked the ground for the sender and it is good.

 

1,146 ohms @ 52 degrees F.

 

Those sensors are very nonlinear, very inaccurate at low temps.

you need the hot measurement. the cold measurement is meaningless

 

That gets me close. The one in the car is way up there in ohms cold, the one on the bench is about 1300 ohms at 60 degrees. I will put them in some boiling water and take a reading. Pretty sure the one in the car is gone.
Thanks for the info

 

Just got my new sensor from Lectric Limited - $12 with the correct blade electrical connector - and its reading 'bout 880ohms at 70*F. The original "as found in the car" read 'bout 700ohms at 70*F and has a blade type connector also.
I've just been though this search as PepBoys sold me a temp switch instead (Stewart Warner) and my newly calibrated temp gauge never moved when i started up to break in the cam. Well of course i left the radiator cap 1/4 loose - Murphy's law - and the radiator boiled over just after the cam was broke in. Now even with a rebuilt temp gauge i never saw temp increase thanks to PepBoys - Murphy's law x 2. Ok i'll quit whinning.
So i've found NAPA and the rest only sell a temp gauge sensor with a button head electrical connector that read 'bout 680ohms at 70*F and would not connect to my brand new engine electrical harness that required a blade type connector. Rather than cut the brand new harness connector and replace i bought the Lectric Limited temp sensor. Lectric Limited claims they did the research for this and thier temp sensor (thermistor) is correct. Heard 'bout Lectric Limited temp sensor here on the forum too.

If u really want to test ur sensor u can get a hot plate and heat up a small pot of wtr while measuring the temp with a thermometer up to boiling/212*F - don't for get to stir. U can just use regular small guage wire for an extention to connect the engine harness temp wire to sensor connector and another wire from brass of sensor to ground (engine). Just remember wire adds resistance and as that sensor gets colder it adds resistance too - i.e. long small dia extention wire will read colder. But i don't know how to adjust the gauge as i had all mine rebuit & recalibrated by Corvette Instrument Services (Rodger Scott) - nice work. BTW i asked Rodger S. for the correct sensor and all i got in reply was that he dosn't sell replacements for C3's.
Good luck. cardo0

 

Thanks for the info. Mine is a smaller thread than the originals due to the AFR heads so I had to expirement when I first did this. I did not write down the number of the sensor so I'll have to expirement again.

 

killer info

 

If you want to heat your thermostat above boiling (212 degree F), you can heat a pan of corn syrup (Karo Corn Syrup) and use a candy thermometer to measure the temperature. You could also use cooking oil to heat up above 212, but I think the corn syrup is best since it's water soluble and easy to clean up.