Temp sending unit question

[427425]

Working on a 65 Chevelle L79 w/factory gauges. Have new wiring harness, and new Delco sending unit for factory gauges. Have also tested gauge. The car is running at 180 degrees, but the temp gauge is on hot. Have changed sending unit to another new Delco, no help. Any ideas what type of sending unit I need?

Thanks - Kevin

[JohnZ]

If the gauge is pegged on HOT, that indicates the sender wire is grounded (or the sender is defective); does it peg to COLD when you disconnect the wire from the sending unit? It should, if the circuit is working.

http://www.yenko.net/ubbthreads/images/graemlins/beers.gif

[427425]

Needle doesn't peg to hot, just moves all the way to H after the car warms up. Infared thermometer shows 175-180 degrees. I tried an older, used sending unit, and it now only comes up @ 3/4 way to H and still running 175-180.
Thanks