My 1982 cooling issue saga - very frustrating

[Harris B.]

For those of you who read my post recently regarding my large rise in temperature on my '82, let me offer an update and that the problem persists. Briefly, water temperature gauge rises rapidly to the red zone of the gauge. When I turn on the heater the gauge returns to normal operating temperature (at least according to the gauge) and stays there. I replaced the thermostat. After my inspection of the internal radiator pipes I observed substantial scale build up and was convinced my radiator was at least partially clogged (and this was supported by the turn on of the heater which served as an additional radiator). I removed the radiator and had a radiator shop recondition the radiator (tanked, "rodded out," and repainted [and the shop left in tact the original radiator tag]). I knew for sure my problem would be solved. Sadly, the problem has not gone away although the speed at which the needle in the gauge rises to the red zone is a bit slower.

But there is more to this. I noticed that when I am driving and the needle starts approaching the red zone and then I turn the heater on, the needle goes back down to normal operating temperature based on the 195 degree thermostat. I also noticed that I can move the heat lever almost to cold and the temperature still remains at operating temperature. However, moving the lever all the way to cold causes the needle to start moving to hot again. Many of you know that there is a vacuum operated positive shutoff valve to the heater core when the heat lever is moved all the way to cold. Moving it just off of cold turns off that positive shutoff valve. This leads me to believe that turning on the heater, even if only slightly, is enough to keep the engine at normal operating temperature. I drove the car at about 5:30 a.m. yesterday for about an hour down a very long, multiple stop light street and the car remained at operating temperature the whole time (with the heater slightly turned on).

I am at a loss of what the problem is and there is not much left to replace or repair. It seems that if the water pump was not working properly, the car would have overheated even with the heater turned on. I really hate to rebuild the water pump unless it is truly not working. When I start the engine cold and take off the radiator cap, I really can't tell whether the pump is working or not. The radiator fluid rises and falls but I don't really see flow of the fluid as if it was being pumped. Is there any test that can be performed to know for sure the pump is working? (other than looking into the radiator or feeling the temperature of the upper radiator hose). Any comments would be welcome.

[Patrick H.]

Re: My 1982 cooling issue saga - very frustrating

Have you used an IR gun to truly verify if your temperature is going up? Or are you relying solely on the gauge?

It might be the sender or a wire, after all. Crazier things have happened.

Compared to your radiator, the heater core is far smaller. I don't think that allowing this extra capacity is doing much to truly fix the problem. And, the odds of the water pump being the cause are small as well.

[Edward J.]

Re: My 1982 cooling issue saga - very frustrating

Harris, it almost sounds like a cooling fan clutch is not coming on. also if your car has heavy duty cooling it also has a aux. fan mount in the fan shroud, which will not come on til about 238 degrees. my advice is find the switch on the cylinder head and make up a ground wire and ground that wire, if you do have this extra fan . and see if the temp will stay at the normal temp. with it running.

[Harris B.]

Re: My 1982 cooling issue saga - very frustrating

Thanks, Edward. Yes, my car does have the auxiliary cooling fan. I was planning to test that fan as well. I am also going to try Patrick's suggestion of using an infrared gun to see if the actual temperature is approximately the same as the gauge. I really do hope these tests will give me some guidance. With all of the difficulty and frustration I have experienced with this car, I have to tell you that as I had the heater on slightly, the temperature gauge at normal, and driving just before first light early in the morning with the lights on and the instrument lights on, it was quite a joy to drive this car. I am glad I bought it. Now if I can just sort through these issues....

[Harris B.]

Re: My 1982 cooling issue saga - very frustrating

At last, I am pleased to report that my cooling issue seems to now be resolved.

About two months after my initial post, above, I noticed the dreaded anti-freeze smell and damp area on the passenger side. Indeed, my heater core had a leak. I went about the project of removing the heater core and having my local radiator shop install a new heater core (but kept the side tanks - including their date code). I installed the heater core and put my Corvette back together. I had the "bouncing" fuel gauge problem and my oil pressure gauge would not go above about 20 psi. I was sure the dampening fluid in the fuel gauge leaked out and I was sure the oil pressure gauge had a bad resistor. So, while I had everything apart, I replaced both gauges.

I could only work on this for a few hours each weekend. After two and a half months, yesterday I was finally able to fill the radiator with good, clean anti-freeze, diluted with distilled water, and added with the use of a spill-free funnel.

I cannot tell you the joy and sense of accomplishment I felt when all of the gauges worked perfectly, including the temperature gauge.

It is a mystery what caused my overheating issue. But, whatever I did, it seems to be working properly now. Thanks to all of you who responded to my thread on this.