I have a problem with the temperature reading backwards.

54, 12 volt, 312. 10 years ago when I got the car (had 239 in it then) the wiring was in tough shape (already converted to 12 volts). I put a new harness in it, everything was great including the gauges.   I put one of the  57 and later Ford gauge voltage reducers in it.  Everything turned out fine.  Been running it for ten years.  Temp gauge always read about 1/3 from cold.  No over heating problems.  The sender was the 57 type.  The gauge stopped reading this season, sender went bad , replaced it with a new sender of the same type.  Gauge then read at the end of the long line on the hot side (still no over heating problem).  I decided to replace the sender with a 54 one (one that I had) .  Changed everything over (including the "bung"):.  Gauge now reads backward - didn't change anything under the dash.  Now reads about the same (needle is on the "E") but it is on cold with the ignition off, goes to hot when the ignition is turned on and goes to the left as engine warms up.  Radiator thermometer reads about 170 degrees with engine fully warmed up.

Question - when some one had the same problem others have suggested to reverse the wires on the gauge.  Will this screw up the gauge if I do this?  Since it was working ok before, I am hesitant to reverse the wires.

Any other insight into the problem?

Thanks


54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ