runs hot in cold weather, cool in hot weather. wtf?
 

my 83 runs at about 1/2 gauge or less when it is nice outside. when it gets cold as hell at night, it runs at around 3/4 gauge. i have tried driving around in the daytime with my lights and heater running, but it stays cool. there have been a few days where it was cold as hell during the day and it ran at 3/4 gauge then too even in the day.

symptoms are:
cold weather-
temps at 3/4,
volts at just over 12
warm weather-
temps 1/2 or less
volts at ~14

im not certain that the voltage reading is related to the problem, it just seems to always be that way.
this is very puzzling to me as i have had many overheating cars before, but never one that did it when it was cold out and not when it was hot out.

items recently replaced on car:
coils, plugs, plug wires, distributor cap, distributor rotor, air filter, fuel filter, oil filter, air pump belt, converted to manual secondaries.

the radiator is reported to be fairly new and looks in excellent condition. coolant mix is good. oil is fresh and level is good.

Fan?

Thermostat?

Guage, balast resister, sending unit? The part diagram I have shows a resistor (balast? Part #FA54-55-490) behind the dash between the left door and the instrument pod. I think this is there to supply consistent voltage to the instruments. If the voltage is not constant, needle readings on "electrical" instruments would vary with the output of the alternator!!! How's you fuel guage working? It could also be as simple as a bad ground! Something for you to think on. Good Luck!

oh yeah. i replaced the thermostat as well. i thought there was something i was leaving out of the list. hehe

hmm.. well all the other gauges read the same night or day. i dont know why the alternator would work better when its warm out than when its cold, but the idea that the gauges would not read consistent with a varying voltage is very interesting. i dont think this is the case, however, since less voltage would mean a lower reading on the gauge, and in this case i am seeing a lower voltage reading while the temp gauge is reading higher than normal.

i think i may change the clutch mechanism for the fan with an old one i have laying around and see if it works any better.

ok, i think i must have been wrong about the voltage. it must just be the headlights and heater fan sucking up all the power. i sat there today in the driveway watching the gauge while turning things on and off. who knew those headlights would draw so much power?
oh well. so ive got two extra fan/clutch assemblies from a friend and tomorrow i will put them on and see how it works out.

Yea, like Spekeez said, I'm guessing its somthing to do with the voltage change, in any case your voltage seems to be temperature dependant, you might want to have the alternator checked, cause if your voltage is close to 12 V, your running off your battery. THe alternator has a built in regulator, that under all conditions below its rated 65A (?might be more or less, but for some reason 65 come to mind?) it should be producing more than that....

absolutely right. i should have the alternator checked. its just that it is soooo shiny and new-looking that i didnt think there could be anything wrong with it. oh well i should have it checked in any case. i put one of the other fan/clutch assy's on and am about to test-drive the car.