Temp. sender puzzle

[BRUCESTUDE]

I'M HAVING PROBLEMS W/A '51 COMMANDER TEMPERATURE SENDING UNIT: IT WAS NOT WORKING; I GROUND THE WIRE AND THE GAUGE PEGGED. I PUT IN A USED SENDER, AND IT WORKED, BUT THEN PEGGED. SO I BOUGHT A NEW (NOT NOS) UNIT, WITH THE SAME RESULTS. I TESTED WITH A SUPPOSEDLY NOS GUAGE, AND A USED CHAMP. GAUGE WITH THE SAME RESULTS. BENCH TESTING (WITH A CUP OF HOT WATER)GAVE THE SAME RESULTS. I EVEN REMOVED AND CLEANED UP THE DUMMY PLATE.
[xx(]WHAT THE HECK IS GOING ON? COMMON SENSE WOULD DICTATE A GROUND IN THE WIRING HARNESS, BUT THE BENCH TEST NIXED THAT IDEA.[B)]

[Dwain G.]

Verify that the black wire from the sender is attached to the outboard terminal of the gauge, that the engine to frame ground strap is in place and tight, and that the battery ground strap is connected to the battery positive terminal.
What is the part numbers of the senders you have tried, and are you sure they are correct?
The sender wire could still be frayed and intermittantly grounding somewhere along its length. You may have to disconnect it from one end at a time and operate the vehicle to observe any movement of the needle.

Dwain G.

[BRUCESTUDE]

THANKS FOR MENTIONING THE GROUND SITUATION. I FOUND OUT THAT THE GAUGE (OR CLUSTER) NEEDS TO BE GROUNDED ALSO. THE DASH IN THIS '51 WAS TAKEN OUT AND PAINTED AT ONE POINT, SO THERE WAS A POOR GROUND. I ADDED AN EXTRA GROUND WIRE TO THE GAUGE CLUSTER, AND CLEANED UP THE FRAME TO BLOCK GROUND STRAP.....VIOLA!