I have a '68 Dart. The temperature guage is usually fine, running at the low end of the normal range, but every now and then, it will relatively quickly rise to the top of normal and even slightly above. When it first did this, I assumed it was overheated and pulled over to check. The radiater was warm but not overly hot; the fluid seemed to be circulating. I went on home. It kept saying I was hottish but eventually settled itself back down to a normal temperature. I changed the sending unit; the problem remained. It did it every time I drove for about 4 months, but is now doing it only intermittently. I don;t like being told the car is hot if it isn;t, and sometime it might actually be. Any ideas on what might be causing this presumably erroneous reading and how to correct? The radiator was rebuilt about 4 months before the problem started. It was thoroughly flushed.

 

Probaly have rust in the system Try a decent cleaner and do a flush,
FF

 

thermostat?
and then what temp thermostat are you using?
in my 65 dart gt i used to use a 190 degree but ended up running no thermostat at all. you might try that first. hope that helps!

Cheers!

 

charon187 has a good point. Mybe your thermostat or the gauge itself is bad. Try to burp the radiator as air can do the same,
FF

 

Thanks, I'll try those things. The thermostat was changed about a year ago, and the radiator was rebuilt at that time (had a little problem and sent the fan through it, which wasn't good for it).