I replaced the water temp. sender with one that was supposed to be the correct original part, Stewart Warner D363 AF. It looks like the one that was in the engine when I got the car. The green cold light on the dash never goes out, even though the engine is at operating temperature. Without having a temperature gauge I am concerned about the actual temperature. Is there an ohm value that should change if the sender is working correctly? The old one did not work at all so I tossed it.

 

I'm not familiar with the 1962 Starfire and if you don't get much response here you might create another thread under the "Other Oldsmobile" section. If the sender is working then could it be your dash light that's the problem? I know very little about electrical stuff, but many of my problems have been a bad ground or corroded contact. If you can get behind the dash light without removing the whole dash assembly you might check its connections. John

 

If it has two terminals it should work, but I've seen the things be bad out of the box.

Quick test to determine if the warning lamps are functioning correctly:

With ignition switch ON, ground each of the temperature switch wires to the engine block and see if the lights come on. That will tell you if the car wiring is good, though I expect you just have a bad sender.

I had one on the 64 that indicated hot almost immediately after the COLD light went out. Pulled it out and saw the sensing bulb was cocked in the switch body to where it grounded as soon as coolant warmed up. New sender solved that issue.

 

Thanks Rocketraider. After looking at the wiring diagram I see that the sender gets it's ground from the block. I removed the sender yesterday and it looks like the copper sensor is touching the body of the sender. I tried prying the sensor away from the body. I will do the test you described and let you know. I can get another two terminal sensor, but they are not stock. They have spade terminals not the pins.

 

I think I have a wiring problem. The green cold light stays on even with the wires at the sender disconnected. When I rebuilt the wiring harness there were two green wires in the big round connector at the back of the speedometer that I was unsure about. I think I have them in the wrong locations on the connector. I am also experiencing a parasitic drain on the battery.

 

The original sending unit has two separate bimetal switches in the sending unit. When cold, the cold switch contacts are closed completing the cold lamp circuit to ground which turns on the Cold lamp. When at operating temperature the switch opens, shutting off the light. When an abnormally high temperature occurs, the hot contacts close completing the circuit to ground for the Hot lamp.