Temperature Gauge Fluctuating, Normal?

Here is a small video of the temperature gauge from my Edsel. It's a 1959 Ranger with a 292. Is it normal for it to fluctuate like this? This video was taken after it had running for about 10-15 minutes.


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i don't think that is normal

i think they used an instrument voltage regulator...i wonder if it;s going bad? do the other gauges fluctuate too?

 

The fuel gauge seems to work fine. That's the only other gauge.

 

A couple of thoughts on diagnosing the issue:
- Use an IR thermometer to test the temp at the same spot as the sending unit. If the temp is actually fluctuating, you'll see.
- Disconnect the gauge and use a multimeter to measure the voltage from the sending unit. If it's constant, the problem is likely to me the gauge.
- And always check for a loose or damaged wire from the sender (not likely to be the ground, though, because the fuel gauge is steady and gauges share a common ground).

 

I believe your car has an electromechanical voltage regulator... put a DVM on the battery and see if the voltage varies in sync with the gauge fluctuation -- if so, the gauge is OK.

 

There's a little box under the dash with two wires hooked to it. When they go bad, the gauge(s) will wander like that.