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| | | | Joined: Jan 2011 Posts: 138 Wrench Fetcher | | Wrench Fetcher Joined: Jan 2011 Posts: 138 | I've looked in the other posts to try to solve this issue but I cant find anything. That being said, my temp gauge is not working properly on my 57 3100.
It was not working at all, but I ran new wires now it will move up to the point where the needle is just over the coldest marking. It does not move after. I let the engine idle for about 30 mins and that's as high as it got. The gauge measures 62 ohms across it. Could the sender be bad?
Alex
57' 3100 (The Bondo Bandit)
Bad rust and worse wiring, but so much fun.
| | | | | Joined: May 2005 Posts: 1,624 Shop Shark | | Shop Shark Joined: May 2005 Posts: 1,624 | The sender must match the gauge. If the truth be known, the sender is a variable resistor and the gauge an ohmmeter of sorts. You can research past posts on testing the sender with hot water with a real ohmmeter. Get different values of resistance for different water temps. Then you plug those resistance values into your gauge. You now know your sysyem works and what those little marks on your temp gauge really mean temperture wise. This of course assumes that the wiring and such is correct and working. BTW, and yes to the electronic techie guys, I know an ohmmeter is really an ampmeter.
Six volt guy living in a twelve volt world
| | | | | Joined: Aug 2009 Posts: 295 Shop Shark | | Shop Shark Joined: Aug 2009 Posts: 295 | It is best to test and check calibration of these on bench. Now that it is in vehicle pull sender and put in cup of hot water with a thermometer you know is correct. Two or three styrofoam coffee cups work well and do not cool down very fast.
Since sender is basically a resistor whose resistance changes with temperature the instrument is an ammeter whose face is cal'd for temperature. The sender must have the correct resistance.
A 0 to 100 (200??) potentiometer / reostat would work well to check the gage.
Dan Bentler | | | | | Joined: Feb 2004 Posts: 29,777 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,777 | Touch the wire from the gauge to the sending unit to a good ground. The engine block or cylinder head makes a good test point, as long as you know the engine is grounded back to the battery properly. The gauge should read full "hot". Now disconnect it, and the gauge should return to the "cold" indication. If the sending unit has the wrong resistance for a particular temperature, the gauge won't indicate accurately. If you can't get full travel on the gauge needle by grounding it, your dash unit has problems.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
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| | | | | Joined: Jan 2011 Posts: 138 Wrench Fetcher | | Wrench Fetcher Joined: Jan 2011 Posts: 138 | I drove it around the block today, and the gauge only rose up a little more than at idle. But that still isn't even a quarter of the way across the gauge. I know my radiator isn't that good lol. I will try some of these techniques later in the week or another weekend. Thanks guys
Alex
57' 3100 (The Bondo Bandit)
Bad rust and worse wiring, but so much fun.
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