Re: OVERHEATING

Posted by HH56 On 2012/7/14 17:01:22

Disconnect the wire and test the resistance to ground with motor cold. It should have lots of Ohms. As the motor warms up the Ohms should decrease gradually. If they become zero before the motor is hot then the sender is bad.

Just as a bit of added information for anyone else with gauge issues, 51-6 Packard (King Seeley thermal type gauge) senders should be in the range of around 80 ohms max and around 10 ohms minimum +/-. Approx same values as some Ford senders which we've found work but NOT GM. Their senders have approx the same resistance but at the opposite ends. Other Packard years use different gauges with different mechanisms or values. Idiot light oil senders are just switches that transition at a specific range so will check out as either short or open.

For troubleshooting, the temp sender would be around 80 when cold and 10 when boiling (around 220 degrees).
Gas is around 80 empty and 10 full.
Oil is 80 when engine off and around 10 at the top end pressure -- not sure what pressure that is presently -- maybe 100 psi.

Our gauge senders should never go to a direct 0 ohm short. That condition for an extended period can damage the gauges.