C2 Temp Gauge/Sender Problem

[Les Jacobs]

The temp gauge reads about 30 to 40 degrees too hot (reads 230, actually 190). The resistance of the sender at 190degrees is 95ohms, 180 degrees/105 ohms, 170/120ohms. Is the problem with the sender or the gauge? Tnx Les

[Ed Jennings]

Re: C2 Temp Gauge/Sender Problem

According to some previous posts in the archives, the sender resistance is too low. Should be closer to 125 ohms @ 180*. Since the sender is much easier and far cheaper to replace than the gauge, I would try it first. Of course, it could be that your 35-40 year old gauge is a little off too. Most of the high reading gauge issues seem to get solved by replacing the sender. About 95% of the folks who have used a Wells TU5 sender (available at Autozone for about $6 and maybe also at NAPA), have reported success. Looks like the GM sender but lacks markings. Won't do for a Top Flight car, but will work for troubleshooting or for a driver. Lectric Limited, and perhaps others are now marketing a sender that is supposed to be correctly marked and accurate. However, I have no firsthand knowledge of its correctness or accuracy.

[Jack H.]

Re: C2 Temp Gauge/Sender Problem

According to the original AC spec for the temp sender (you can see in my Rocky Mtn Chapter newsletter, Sept/Oct 2002 edition, free for the download at www.ncrsrmc.org), the loci for acceptable response is:

170F 110-130 ohm
180F 100-116 ohm
190F 90-101 ohm

These numbers are within 5%, typical graph inference accuracy....