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Discussion Starter · #1 ·
My temp gauge reads at the 1/4 mark when at operating temp (180 t-stat). I want it to read at the 1/2 mark. I have replaced both the gauge and the sending unit with no changes. What can be done to recalibrate the gauge to make it read at 1/2 mark when at operating temp?

Thanks for any help, Jeff
 

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Not enough info…. You could be asking about your barbeque pit guage…that’s the only gauge I’m looking at today. :D
 

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Aftermarket gauge or factory?
 

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Discussion Starter · #4 ·
Brian, I tried an aftermarket gauge with the resistor built in and a factory replacement with the external resistor same results with both.

Geezer your on the wrong forum if you think its for a BBQ but its for a 69 and it is a camaro.
 

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And you are using a temp gauge sender unit not a temp switch for an idiot light vehicle?

You can test the output of the sender you have by grounding it and dropping it into a pot of boiling water with a candy thermometer then read off the output of the sender it should increase output, if it stays steady and then goes live then it is not a gauge sender but a switch for an idiot light.

Search Everett's recent posts on how to read off the output at temp marks with a multi meter. Someone else within the past month had the same issue.

Brian
 

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Discussion Starter · #6 ·
Yes its a gauge sending unit and I have tried two of them and both read the same.
Both are good and I checked their resistance in boiling water and freezing water, both are within a few ohms of each other.

I did a search and found Everetts posts. It looks like I may have to alter the resistor across the back of the gauge to get the results Im after. I am pretty close to the 10 oclock position when at 180* and I think Everett said that 12 oclock is 212*.
 

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Mine has never gone above 1/3rd and mostly sits at 1/4. Installed an EZ EFI and in checking it on the hand held 1/4 = 190F. Nice thing about the EZ hand held.
 

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Yes, the 1/4 mark is generally 180°F and the top mark is 210°F.
Thermostats start to open at temperature stamped and generally fully open 10° later.
Might try a 195°F thermostat to run at mid range.
 

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Discussion Starter · #10 ·
Picked up a 560 ohm resistor from radio shack and it got it to about 1/2 at 190*-195*, now to see when it cools down if the needle will follow.
 

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Gauge sending units have a negative temperature coefficent - the hotter they get, the lower the resistance reading between the spade/stud and body.
The lower the resistance, the hotter temp indicated on the gauge.
Around 180-200 ohms, might indicate 1/4 mark. Lesser ohms indicates higher temp.
 

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Discussion Starter · #12 ·
I checked two sending units and found these results:
unit#1 32*=1150 ohms
unit#1 212*=.25 ohms

unit#2 32*=1050 ohms
unit#2 212*=.70 ohms
 

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I suspect the 212° readings are incorrect as they would indicate 260°/peg the gauge.
You might want to borrow/rent/buy a better digital multimeter or buy an assortment of known resistors from Radio Shack and compare the DMM readings to the actual resistance measured.

Also, you might pick up a 1/2 watt or better, 0-1K, or 0-2500, or 0-5K potentiometer and sub in the pot for the sender to get an idea of the resistance needed for gauge to indicate the degrees.
 

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Discussion Starter · #14 ·
I did something similar. I brought the car up to operating temp ( I use an Infrared temp gun on the sending unit, 190*-195*) temp gauge was about at 10 oclock. I took a potentiometer from grd to the gn lead on the sending unit and I dialed in my 12 oclock reading on the temp gauge. Then I disconnected the potentiometer and read its value. I came up with 580 ohms, went to radio shack and bought the closest resistor they had to 580 ohms. I then installed the resistor in place of the potentiometer and checked it last night. Worked great, temp gauge now reads at 12 oclock when at operating temp and goes back down when cold. Next step is to wire it in at the back of the gauge.
 
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