How do you check the temp gauge?

[Vinny]

I have a 1960 that has the temp gauge reading about 215 when warm.
I have IR'D the motor and it is constant at 180 degrees. I have just replaced the sending unit from autozone as recommended with a tu-6
the readings are the same. (Maybe slightly higher -5 degrees) but still constant on the gauge. I suspect that I have a faulty gauge. Can you direct me on a trouble shoot on the 60 gauge to be certain? The unit reads 0 with the sending wire disconnected and "pegged" with the unit grounded. thanks for your help, vinny

 

[midyearroadster427]

on another board they mentioned a problem like yours....someone mentioned that you can get an adjustable capacitor or something from one of the major suppliers...I guess it ties in to your temp wire from the sending unit and it has a tiny screw adjustment in it...and you dial in the dash guage with the help of an ir gun until they match...I will attempt to find out the who and where to get it from ...

 

[Hib Halverson]

If you used an IR thermometer on the thermostat housing and saw 180 while seeing 215 on the gauge and when the circuit is open you see 0 and grounded you see full scale...first thing I'd do is measure the resistance of the wire from the gauge to the sender. It should be an ohm or so. If it's above that, replace the wire. Then, test the ground path from the gauge housing to the frame. If there's high resistance there, fix it.

Then, if you still have a large disparity between ECT measured with your IR thermometer and what the gauge reads, replace the gauge.

 

[JohnZ]

I have a 1960 that has the temp gauge reading about 215 when warm.
I have IR'D the motor and it is constant at 180 degrees. I have just replaced the sending unit from autozone as recommended with a tu-6
the readings are the same. (Maybe slightly higher -5 degrees) but still constant on the gauge. I suspect that I have a faulty gauge. Can you direct me on a trouble shoot on the 60 gauge to be certain? The unit reads 0 with the sending wire disconnected and "pegged" with the unit grounded. thanks for your help, vinny

Your gauge checks out fine (pegged cold with the sender wire removed and pegged hot with the wire grounded). The issue is with the sender, and is VERY common; nobody makes a sender that's calibrated to the original gauge, except for dumb luck. The most common cure is to use the variable resistor kit sold by Corvette Central just for this purpose; since the gauge response profile is non-linear, the added resistor will only calibrate the gauge so it's accurate at the temperature you choose, but it won't be that far off.

If you I.R. the thermostat housing and it's 180*F and adjust the resistor so the gauge reads 180*F, at least you'll know the gauge is working and telling you something.

 

[Vinny]

thanks for the info john. Ill check out the kit, vinny

Your gauge checks out fine (pegged cold with the sender wire removed and pegged hot with the wire grounded). The issue is with the sender, and is VERY common; nobody makes a sender that's calibrated to the original gauge, except for dumb luck. The most common cure is to use the variable resistor kit sold by Corvette Central just for this purpose; since the gauge response profile is non-linear, the added resistor will only calibrate the gauge so it's accurate at the temperature you choose, but it won't be that far off.

If you I.R. the thermostat housing and it's 180*F and adjust the resistor so the gauge reads 180*F, at least you'll know the gauge is working and telling you something.

 

[magicv8]

if an unprotected sender wire is laying on the intake msnifold heat riser crossover, it will transmit the heat to the sender as well as the electrons from the gauge.