Crazy overheating problem
 

Can anybody help? I have a 1982 5.0. Since the cool weather arrived, I had to turn on the heat. When I turned on the heater, the temp. gauge started to climb like mad & the air out of the vents is not all that hot. I recently have installed a new thermostat, temp. sender & a fan clutch. When you turn the heat off, the gauge goes back to normal - I am puzzled. :confused: I tried to turn on the AC to see what happened, nice & cool 59 degree air out of the vent - temp gauge normal.

Anybody have any ideas to set me on the path to cozy warmth? I know usually when you put the heat on, the temp gauge goes down - this is why it's got me scratching my head. I would really appreciate any helpful information. Thanks!

All I can think is that you have a problem with your heater core.

try a manual gauge first! i'd bet it could be the problem.

Still high temp on gauge, but not really
 

I went to ford and got the Temp sender, still showing high temp kinda, but the temp at the radiator is only 115 degrees. Any chance the little bypass tube has something to do with this, it seems kind of crimped but theres enough room for flow, I just don't know if it's enough. Thanks for any help.