Temperature gauge
Thread Starter
Heel & Toe
Joined: Sep 2012
Posts: 24
Likes: 0
From: Lyckeby Southern part of Sweden
Temperature gauge
Hallo everybody.
I hope that you have had a nice christmas with a lot of nice corvette presents.
My question.
I have by mistake moved the needle in my temperature gauge.
Have i broken it now?
Can i just take it back and if so where should it be (i have forgotten).
It worked before. I dont how it is now, i cant start the engine because of other things that i´m doing now during the winter.
Should i just replace it and also the sending unit, they are not so very expensive but important to have in function i think.
If it´s possibely it should be nice to see a picture with the needle in the correct position.
Regards Anders
I hope that you have had a nice christmas with a lot of nice corvette presents.
My question.
I have by mistake moved the needle in my temperature gauge.
Have i broken it now?
Can i just take it back and if so where should it be (i have forgotten).
It worked before. I dont how it is now, i cant start the engine because of other things that i´m doing now during the winter.
Should i just replace it and also the sending unit, they are not so very expensive but important to have in function i think.
If it´s possibely it should be nice to see a picture with the needle in the correct position.
Regards Anders
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Did you just move the needle/mechanism? Or, did the needle slip on its shaft? If you just bumped the needle so it is repositioned, don't worry about it...you've changed nothing.
If the needle actually changed orientation to the shaft, you will have to reposition it correctly. In that case, maybe Willcox has some advice for you. I think you would need to determine the resistance reading of the temp sender [at normal operating temp] then power the gauge and insert a substitute resistance of the same value in order to set the gauge--then remove the needle and replace it at the correct temp position.
With an earlier model C3, which doesn't have the electronic circuit board in the gauge cluster, it would be easier. But, I'm not sure of how to get that done with the later version system.
If the needle actually changed orientation to the shaft, you will have to reposition it correctly. In that case, maybe Willcox has some advice for you. I think you would need to determine the resistance reading of the temp sender [at normal operating temp] then power the gauge and insert a substitute resistance of the same value in order to set the gauge--then remove the needle and replace it at the correct temp position.
With an earlier model C3, which doesn't have the electronic circuit board in the gauge cluster, it would be easier. But, I'm not sure of how to get that done with the later version system.
Thread Starter
Heel & Toe
Joined: Sep 2012
Posts: 24
Likes: 0
From: Lyckeby Southern part of Sweden
Temperature gauge
Hallo there 7T1vette.
Thank you for the answer.
I´m not sure really if the needle have sliped on its shaft or if it was the the shaft that moved.
You say that i have to reposition it correctly.
Can´t that be done with boiling water with a thermometer in it, put the sending unit in it and then just replace the needle to the correct position?
I assume that i have to ground it to engine block or some where else.
I think it strange that when i look at pictures of this gauge from differerent suppliers that the needle is not allways in the same position. Do that mean that even a new one must be calibrated to the correct possition??
Forgive me for my sometimes poor english. From Sweden you know.
Regards Anders
Thank you for the answer.
I´m not sure really if the needle have sliped on its shaft or if it was the the shaft that moved.
You say that i have to reposition it correctly.
Can´t that be done with boiling water with a thermometer in it, put the sending unit in it and then just replace the needle to the correct position?
I assume that i have to ground it to engine block or some where else.
I think it strange that when i look at pictures of this gauge from differerent suppliers that the needle is not allways in the same position. Do that mean that even a new one must be calibrated to the correct possition??
Forgive me for my sometimes poor english. From Sweden you know.
Regards Anders
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
If you just bumped the needle, chances are that there was no change of the relationship of the needle to the indicator shaft. You would need to have bumped it when the needle was to the end of [mechanical] travel of the gauge for it to slip on the shaft.
But, within the range of gauge travel, there is very little resistance to motion of the shaft/needle. It is easily bumped/moved; but there will be NO change in the gauge's calibration.
But, within the range of gauge travel, there is very little resistance to motion of the shaft/needle. It is easily bumped/moved; but there will be NO change in the gauge's calibration.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
As far as 'how to test' the gauge when it's out of the vehicle: for early C3's, without the gauge circuit board in the gauge cluster, you need the gauge, the sender, some jumper wires, a 12v. battery (small batteries are fine...a battery charger is NOT, as it does not provide 'smoothed' voltage without a battery in the system) AND a pot of water just brought to a boil. Connect wiring as needed, hang the sender in the boiling water (don't just lay it on the bottom of the pot), and see if the gauge needle is close to 212*F on the gauge. If not, move the needle [USE CORRECT METHODOLOGY TO DO THIS OR THE GAUGE COULD BE DAMAGED].
I do not know if the circuit board needs to be in the system for testing on the later C3 gauges. That's why I suggested that Willcox may have additional info for your particular situation.
I do not know if the circuit board needs to be in the system for testing on the later C3 gauges. That's why I suggested that Willcox may have additional info for your particular situation.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
As 7t said above... If you bump the needle it will not hurt anything. The needle shaft will move freely with the needle. If you have removed the needle from the gauge then you have an entirely different issue.
We use the chart below to position the needles when working on the gauges.
To do this you'll need an adjustable linear potentiometer (Pot) or some other form of resistors to create 79 ohms of input to be applied to the ohms terminal show below. If you apply power and ground to the gauge with 79 ohms input you can place the needle on the 210 mark and "Set it" (light tap). Once you have the needle back in place then test it to see if it coincides with the other readings on the chart.
We use the chart below to position the needles when working on the gauges.
To do this you'll need an adjustable linear potentiometer (Pot) or some other form of resistors to create 79 ohms of input to be applied to the ohms terminal show below. If you apply power and ground to the gauge with 79 ohms input you can place the needle on the 210 mark and "Set it" (light tap). Once you have the needle back in place then test it to see if it coincides with the other readings on the chart.
Thread Starter
Heel & Toe
Joined: Sep 2012
Posts: 24
Likes: 0
From: Lyckeby Southern part of Sweden
Temperature gauge
Hallo there and thank you for the answers.
I think i now know how to do this.
However i´m still a little bit confused.
Please have patience with me.
When i have calibrated the gauge, what position will then the needle have with the engine totally cold?
REGARDS AND HAVE VERY GOOD CORVETTE YEAR.
Anders
I think i now know how to do this.
However i´m still a little bit confused.
Please have patience with me.
When i have calibrated the gauge, what position will then the needle have with the engine totally cold?
REGARDS AND HAVE VERY GOOD CORVETTE YEAR.
Anders
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
When the engine is cold and the ignition switch is turned to "ON" position (engine not running), the needle on the gauge should indicate the temperature of the cylinder head. If it is 100*F, it should read somewhere around 100*F; if it is 32*F [0*C], the needle should be all the way to the left end of the scale.
As far as how to use this gauge: it is merely there to give you an indication that "all is well" with your engine. You should know where the needle will read when the engine is up to operating temps. When you scan that gauge, you would be looking for the needle to be at that spot. You can also watch the rate at which it comes up to temps, and take note if that behavior stays the same...or not. Likewise, if the needle becomes erratic or increases in temp very much. You're looking for any gauge behavior that doesn't appear to be similar than what you are used to seeing.
Will that gauge be "accurate"? No. At least, don't expect it to be any more accurate than within 20*F (10*C approx). But, it will be very repeatable, so that you can determine "change". That's all the gauge is for.
As far as how to use this gauge: it is merely there to give you an indication that "all is well" with your engine. You should know where the needle will read when the engine is up to operating temps. When you scan that gauge, you would be looking for the needle to be at that spot. You can also watch the rate at which it comes up to temps, and take note if that behavior stays the same...or not. Likewise, if the needle becomes erratic or increases in temp very much. You're looking for any gauge behavior that doesn't appear to be similar than what you are used to seeing.
Will that gauge be "accurate"? No. At least, don't expect it to be any more accurate than within 20*F (10*C approx). But, it will be very repeatable, so that you can determine "change". That's all the gauge is for.
Last edited by 7T1vette; Dec 31, 2012 at 05:03 PM.
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Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Hallo there and thank you for the answers.
I think i now know how to do this.
However i´m still a little bit confused.
Please have patience with me.
When i have calibrated the gauge, what position will then the needle have with the engine totally cold?
REGARDS AND HAVE VERY GOOD CORVETTE YEAR.
Anders
I think i now know how to do this.
However i´m still a little bit confused.
Please have patience with me.
When i have calibrated the gauge, what position will then the needle have with the engine totally cold?
REGARDS AND HAVE VERY GOOD CORVETTE YEAR.
Anders
You'll need to find some resistors or purchase a pot online to set the needle.
You must have power, ground and input ohms.
Willcox
Thread Starter
Heel & Toe
Joined: Sep 2012
Posts: 24
Likes: 0
From: Lyckeby Southern part of Sweden
Temperature gauge
Hallo again and once again thank you, you are very helpful.
"Willcox" i will calibrate the gauge tomorrow by using a potentiometer as you have informed me.
"7T1vette" Thank you very much for your information, i think i have understand earlier that these gauges only can be used as an indication if something is happening. So you have helped me to be convinced of that, thanks.
Have very good NEW COVETTE YEAR both of you and once again thank you for the good help.
I will replay the result in a couple of days.
Regards
Anders
"Willcox" i will calibrate the gauge tomorrow by using a potentiometer as you have informed me.
"7T1vette" Thank you very much for your information, i think i have understand earlier that these gauges only can be used as an indication if something is happening. So you have helped me to be convinced of that, thanks.
Have very good NEW COVETTE YEAR both of you and once again thank you for the good help.
I will replay the result in a couple of days.
Regards
Anders
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,850
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
75-76 used a 200* center marked gauge 72-74 used a white faced gauge that looked like this one.
1968-1971 used pretty much the same gauge on the letters were green.
1968-1971 used pretty much the same gauge on the letters were green.