The temp gauge didn't work(among other items) when I purchased my '56. last week I got around to troubleshooting the problem and found the gauge was wired backwards. Now when I turn the ignition on the gauge goes to 160*. When I disconnect the sender it still goes to 160*. I checked the sender and it reads 680 ohms. I checked the gauge with a 47 ohm resistor to ground and the gauge will read 210*. When the ignition is off the gauge drops all the way to the left. Is there something I can do to correct the gauge or should I send it to Corvette Specialities of Maryland. I don't need for the gauge to be restored, just repaired.

 

Let me preface this by stating that I am an amatuer. But I recently learned a lot about the temp gauge on my 63 Vette that may be helpful. First, a reading of 210 F with 47 ohms to the sending side of the gauge seems too low, so the gauge may be off. But before I did anything else, I would check the resistance of the sender wire (cold engine) where it connects to the back of the gauge. If there are no shorts in the wiring, you should see more than 500 ohms. If it is significantly lower (e.g., 150 ohms), that may explain why your gauge reads 160 F as soon as you turn it on. If that is the case, you probably have frayed insulation or some other short circuit in the sending wire. If the wiring from the sending unit checks out ok, you can check the gauge by temporarily wiring known resistors in place of the sending unit and checking the gauge readings. If the gauge needle swings appropriately with changes in resistance, but is pointing consistently to the wrong temperature (e.g, reads 160 when it should read 190), you may be able to remove the needle and reposition it on the shaft so it points to the correct temperature.

There was a lot of good advice on my thread when I had a temp gauge problem several weeks ago. You should be able to find it. Also, I will try to email an article that should help. Good luck.

 

To isolate the problem, try running a temporary wire directly from the gauge to the sender, out the window, over the hood, etc. With the ignition on, momentarily ground the wire. The gauge should read full scale (hot). With the wire disconnected, the gauge should read no scale (full cold). The sender should read about 700 ohms at room temp. This should point you in the right direction.