My 71 Duster with 198 slant six just started overheating according to the gauge on day. I already have a new radiator in it so, I supposed it was the thermostat. I went ahead and got a new one, they're cheap enough. I replaced it with a 195 degree thermostat and had to get a new housing too after breaking it in the process. Now as soon as I turn the key over, the temp gauge jumps right to max. It buries itself on the high end, I drove it around town to see if the gauge was just reading wrong. It did go up and down for a few blocks, but is now stuck back at the high end. I am to worried to drive it anymore. Also when I shut it off, the needle goes down to cold immediately. This seems odd to me, I can smell burning antifreeze but not sure if that is just some over spill from when I replaced the thermostat. Any ideas?????

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my guess would be a shorted circuit in the gauge wiring to the sender. If your other gauges are not "acting up," the gauge itself might be bad but I doubt it. Check the resistance on the wire to the sender with an OHM meter.

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1979 W150 Shortbox
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The Good Life.

Are there any signs of overheating besides what the gauge says? If it goes up "instantly" there's no way your engine can heat up (or cool down) that fast.

Any spewing coolant steaming out of the overflow when driving? Excessive heat in the engine bay?

Could be the voltage limiter that plugs into the circuit board on the back of your gauge cluster, it regulates the temp gauge and fuel gauge.

brian

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Have you done anything lately to pinch a wire or ground it somehow? Check the sensor wire, sensor is screwed into the head near the thermostat housing. Is the wire secure to the sensor? Run along the wire, is it pinched anywhere?

brian

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I'd start with the sensor. When my oil pressure gauge went out it made it look like I had no oil pressure, and I suspect it would be the same scenario with a temperature sensor.

I don't trust factory gauges or idiot lights after they get to be a bit aged.

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I assume this above reaction was with cool engine?

If so, be looking for a bare temperature gage signal wire grounding somewhere between gage and sender.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
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Why the 195* stat, what's wrong with a 180*?

What's wrong with 195 degree thermostat? That's what I've been using the past 15 years.

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If it was easy, everybody would be doing it.

A 195° thermostat is fine, and a colder-rated thermostat is not a correct solution to an overheating problem, but this what's under discussion isn't an overheating problem -- it's an electrical/gauge issue.

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OK, well I haven't found a bare wire yet, but I don't have an OHM meter in my possession. Anyways it did have coolant leak after from the overflow after I drove it for a few miles. It also dieseled a for a second, when I turned it off halfway through my test run. I let it cool for about 10 minutes and then drove it home with a maxed out temp. gauge, but had absolutely no other issues. The car ran fine. I did add more coolant after I replaced the thermostat so this may of just been excess flushing out, not sure. I hope this is just a faulty gauge.

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