I finally got time to check the sender. Engine running 3-5 minutes, the sender was reading 63-66 ohms. gauge on the edge of red. The chart seems to indicate it would be over 200 degrees, but the block temp next to the sender is 158 degrees with a digital thermometer. I realize the coolant will be hotter, bit 50 degrees seems excessive. Coolant temp in the overflow tank was 110f. The secondary fans didn't come on unless I put the hvac control to a/c.
I'm going to get a sensor from Chad this weekend, and swap it out. If the used one reads better, I'll order another new one.