[68ragtop]

Just curious if there is a temperature based ohm chart for sending units? Had one of my cars out today that I don't drive often & it was a warm day. Gauge was showing near 220 & making me nervous as I had no seen it that high before. Got home & IR temp check the intake & thermostat housing & it was 190 while showing 220 in the car. So that was a relief, but would like to see if the error is in the gage or in the sending unit. Just don't like visualy seeing the gage over 200, makes me keep hawking over it .

Any thoughts? I found this on another site, but not sure if the data is accurate.

415 ohms = 100 degrees.
50 ohms = 250 degrees.
79 ohms = 210 degrees.

Is this accurate info & is there a more complete chart out there?

[OG68]

Somewhat close to the figures I have for my 68.

600-700 ohms - Cold
44-45 ohms - Half Scale - 210*
51 ohms - Full scale - 250*

Pete Serio told me that for the 68, 1/4 scale = 180* (don't have an ohms reading for that) and 1/2 scale was 210*

[Shiny]

Originally Posted by OG68

Somewhat close to the figures I have for my 68.

600-700 ohms - Cold
44-45 ohms - Half Scale - 210*
51 ohms - Full scale - 250*

Pete Serio told me that for the 68, 1/4 scale = 180* (don't have an ohms reading for that) and 1/2 scale was 210*

Is it possible you have the 210 and 250 ohms values reversed? Seems the "Cold" reading is inconsistent...

[Shiny]

Originally Posted by 68ragtop

... Any thoughts? I found this on another site, but not sure if the data is accurate.

415 ohms = 100 degrees.
50 ohms = 250 degrees.
79 ohms = 210 degrees.

I have no clue if your numbers are right but looks like a reasonable relationship at least. I plotted and fit to an equation in case you want to give it a shot...

Won't help you a bit if it isn't the right calibration but I like to plot graphs...

The sensitivity at the hot side makes a good argument for asking your question. Won't take much drift in either the sensor or the gauge to cause a big error. Another GM engineering design decision probably driven by cost yet controlled well enough to meet the "design goals" (wonder how accurate they intended it to be?). Hopefully you can trust your IR thermometer!

Is this accurate info & is there a more complete chart out there?

Again I have no clue... will be interesting to learn the truth...

[OG68]

Originally Posted by Shiny

Is it possible you have the 210 and 250 ohms values reversed? Seems the "Cold" reading is inconsistent...

Yep. You're right. I don't know how that got in there. but it matches the oil sender I had written directly above it.

Should be:

600-700 ohms - Cold
76 ohms - 1/2 scale
51 ohms - full scale

Thanks for the correction