Yet another water temperature gauge problem - I could use some help
This takes a little explanation. Sorry this post is so long but bear with me.
About four years ago I purchased my dream car, a 1982 light blue metallic Corvette with about 25,000 miles. It was Bloomington Gold certified which gave me a little bit of comfort that "bubba" had not been in it or at least not much. After purchasing the car, I found that as the engine warmed up, the water temperature gauge needle would rise to almost the red zone but would then move quickly back down to normal operating temperature (responding to the thermostat opening to cool the engine). However, when accelerating or any load was placed on the engine (causing it to warm up), the water temperature needle would again rise to near the red zone area and then the needle would return to the normal operating temperature. It was as if the gauge was hyper-sensitive to changes in water temperature as the thermostat worked to get the water temperature back to normal.
The first time the gauge exhibited this behavior it startled me and I feared that the engine was overheating. Of course, as any neophyte at car repairs will do, I started replacing parts rather than truly testing and properly diagnosing the problem. A new thermostat did not help. A new replacement gauge did not help. Then, I took the car to my local trusted mechanic. He hooked up his computer diagnostic scanner (1980 California Corvettes and all 1981 and 1982 Corvettes had computers). The scanner was able to read the water temperature through the scanner. We then test drove the car. While the water temperature gauge needle would move to near the red zone on the face of the gauge, the scanner displayed only slight changes in temperature. It was clear to me that the problem was with the gauge, not the sender or thermostat. I did check the coolant level just to make sure that was not the problem.
I believe that the resistor's job is to stop large fluctuations in needle movement. Rather, it allows changes but slows down the needle's reaction to changes in sender current. If my belief is correct, then a bad resistor (or incorrectly installed resistor and gauge) is the root cause of my problem.
I located a new old stock (NOS) gauge. Within the box for the gauge was a resistor (the old style color coded resistor) in a little plastic bag packed with the gauge.
I proceeded to remove the old after market gauge that I previously installed and installed my new gauge. I was very careful to install (using a Willcox youtube videos as a guide) with the proper insulating washers to insulate the gauge from the metal center gauge cluster housing. During this replacement I tested the resistor that was packaged with the NOS gauge and it did, offer resistance (I don't recall how much resistance). Interestingly, the resistor on the replacement gauge was just a piece of plastic with no metal and no conductivity at all. This further supported my belief that the problem lies with the resistor.
Sadly, after installing the NOS gauge and connecting the center gauge cluster back in the car, the exact same problem was exhibited with the NOS gauge. I am still convinced that the problem is with the resistor. However, I think the NOS resistor is good and of proper resistance. Rather, I think the problem is that I have not connected the gauge to the cluster and to the printed circuit properly (despite the fact that I meticulously followed the Willcox videos).
Does anyone have a detailed schematic or some other guide to how the water temperature gauge is to be installed in a 1982 Corvette? I know there were changes in how these gauges worked and how they were installed over the years. I think though that all 1978 through 1982 Corvettes have the same system.
Please help!
About four years ago I purchased my dream car, a 1982 light blue metallic Corvette with about 25,000 miles. It was Bloomington Gold certified which gave me a little bit of comfort that "bubba" had not been in it or at least not much. After purchasing the car, I found that as the engine warmed up, the water temperature gauge needle would rise to almost the red zone but would then move quickly back down to normal operating temperature (responding to the thermostat opening to cool the engine). However, when accelerating or any load was placed on the engine (causing it to warm up), the water temperature needle would again rise to near the red zone area and then the needle would return to the normal operating temperature. It was as if the gauge was hyper-sensitive to changes in water temperature as the thermostat worked to get the water temperature back to normal.
The first time the gauge exhibited this behavior it startled me and I feared that the engine was overheating. Of course, as any neophyte at car repairs will do, I started replacing parts rather than truly testing and properly diagnosing the problem. A new thermostat did not help. A new replacement gauge did not help. Then, I took the car to my local trusted mechanic. He hooked up his computer diagnostic scanner (1980 California Corvettes and all 1981 and 1982 Corvettes had computers). The scanner was able to read the water temperature through the scanner. We then test drove the car. While the water temperature gauge needle would move to near the red zone on the face of the gauge, the scanner displayed only slight changes in temperature. It was clear to me that the problem was with the gauge, not the sender or thermostat. I did check the coolant level just to make sure that was not the problem.
I believe that the resistor's job is to stop large fluctuations in needle movement. Rather, it allows changes but slows down the needle's reaction to changes in sender current. If my belief is correct, then a bad resistor (or incorrectly installed resistor and gauge) is the root cause of my problem.
I located a new old stock (NOS) gauge. Within the box for the gauge was a resistor (the old style color coded resistor) in a little plastic bag packed with the gauge.
I proceeded to remove the old after market gauge that I previously installed and installed my new gauge. I was very careful to install (using a Willcox youtube videos as a guide) with the proper insulating washers to insulate the gauge from the metal center gauge cluster housing. During this replacement I tested the resistor that was packaged with the NOS gauge and it did, offer resistance (I don't recall how much resistance). Interestingly, the resistor on the replacement gauge was just a piece of plastic with no metal and no conductivity at all. This further supported my belief that the problem lies with the resistor.
Sadly, after installing the NOS gauge and connecting the center gauge cluster back in the car, the exact same problem was exhibited with the NOS gauge. I am still convinced that the problem is with the resistor. However, I think the NOS resistor is good and of proper resistance. Rather, I think the problem is that I have not connected the gauge to the cluster and to the printed circuit properly (despite the fact that I meticulously followed the Willcox videos).
Does anyone have a detailed schematic or some other guide to how the water temperature gauge is to be installed in a 1982 Corvette? I know there were changes in how these gauges worked and how they were installed over the years. I think though that all 1978 through 1982 Corvettes have the same system.
Please help!
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