Packard Forum Index » Post-War (1946-54)

I am in the process of rewiring my 49 eight sedan. Before I connected anything the fuel gauge reads E, the oil pressure 0, which sounds normal, but the temp gauge needle is to the right, reading H. (A spare instrument panel I have also reads the same, temp on H.) With the temp gauge connected to the sender unit and power on, it is still on H. Any ideas? Gauge faulty or sender faulty?
Gary

The "at rest" (ignition off) position of the temperature gauge is at the Hot position.

The gauges in the 48-50 models are somewhat unique for Packard in that they are the only years that use a pulsing on/off action from the senders instead of a straight resistance change as was provided for all other years that had electric gauges. A heater around a bimetal strip in the senders is in series with a heater around a bimetal in the gauge and gets voltage and current thru the gauge heater. Sender heater starts to heat which wants to move the sender bimetal one direction to close a contact to ground. The fuel sender float, oil pressure or the temperature acts on the bimetal in the opposite direction to oppose the heater. Depending on how strong the variables act on opposing the sender heater the pulses change in length or duration which affects the gauge bimetal so it heats or cools and the needle moves in proportion to the on/off timing of the pulses.

Since the gauge needle does not seem to move, first thing to check is if you have voltage at the gauge. The gauge should be directly tied to the others via some jumper strips so if the other gauges work then if connections are clean and tight 6v should be present. If so MOMENTARILY ground the wire at the sender going to the other gauge terminal and the gauge should start to move toward cold. As soon as you see the needle moving disconnect the ground or turn off the power. If the needle moves, the sender or a bad ground between the sender and the head is the most likely issue. If the needle still does not move, a broken wire or bad connection between the gauge and sender or a burned out gauge is the more likely problem. If the old insulation cracked or fell off and the wire to the sender shorted letting the gauge stay grounded it could have burned out.

G'day Gary,
Good to see you made it onto PackardInfo,

Now that you're here, I invite you to include your '49 Eight Sedan in the Packard Owner's Registry.

Thank you Howard and Owen. I fired up the car for a few minutes and the gauge woke up, and went down to about 1/4 way between C and H. So it looks like my gauge and sender work, not that I can see a white needle against a silver backing anyway... Who designed these things? Did he ever get caught and sent back to the asylum? Gary