Datsun Roadster Forum-311s.org

Has anyone had a problem with a sending unit that sends the wrong voltage to the the temperature guage? Makes the guage read hot when its at normal temps?

Yes, the senders seem to read high as they age. You can check the actual temp with an IR or candy thermometer.

Mine reads high. Gauge is is pegged when temp at elbow is only around 210.

You can calibrate it by putting a resistor in series with the sender. Get a 100 ohm variable resistor and put in line with the sender. Adjust to correct the gauge. Then measure the adjustable resistor and install a fixed one in it's place. However, if your gas gauge is also reading high then check your instrument voltage regulator.

I checked the water temp with a meat thermometer and it was about 70 degrees off. Its a new sending unit so the resistor sounds like the way to go to get it exact. Thanks

The gauge in my '65 1500 is actually adjustable, I don't know about later models.
There is a small hole in the rear of the gauge case and you can move the mechanism to fine tune the reading to that measured by a reliable source e.g. a thermo-couple device.

I'm having the same issue with my 67 1/2 1600. Gauge seems to be working but pegs the needle in a relatively short time. My IR scanner shows the actual temperature to be about 180 degrees. I'm curious to know if anyone knows if the factory gauge in my car has an adjustment like Nissanman's. If so, I'll pull it out and see if I can calibrate it. Otherwise I'll try the resistor. It's more than a little disconcerting to see the needle pegged while driving.

When you view the rear of the gauge case, look for a plug or a round hole ~8mm diam.

Is adjustment with a small screw driver, an allen wrench or???

Mine was a slide type device which you could move left and right with a small screwdriver.

Cool. Out it comes tomorrow.

Good luck! Have a good look at the rear case and if it has a hole, use a decent magnifying glass to inspect the interior.

The 66-67 temp gauge does have an adjustment wheel. Also, the fuel and oil gauges have one.

Steve, good to know. My fuel gauge works, but has a very small range. When it's full the gauge sits at 3/4 and when it's empty it shows 1/4 full. Do you know whether this is a gauge calibration issue or a sending unit issue?

steve_car wrote:The 66-67 temp gauge does have an adjustment wheel. Also, the fuel and oil gauges have one.

That is good to know. Thanks Steve!