VITIV Coupe

I guess my temperature gauge has malfunctioned, it is spiked straight across at 240, even with the car off. Any of you fine wrenches Know what would cause this. I checked all my wiring to the gauge and to the sending unit. Could the gauge be fried and the sending unit also? How do I check?
Thanks, Leo

Nowhere Man

unplug the sending unit. it should stay at zero with the key on

VITIV Coupe

I did as you said and even started the car, made no difference, still pegged @ 240. When I did start the car there was movement in the needle, just a twitch, but it did move. This is the sending unit I hope.

JohnZ

With the key "on", remove the green wire connector from the temp sending unit - the gauge should peg to full cold; then touch the connector terminal to the engine, and the gauge should peg to full hot. If the gauge reacts that way, the gauge is fine, and the sending unit is faulty.

Nowhere Man

That's the sending unit There are write ups on the gauge and how to fix on this Fourm somewhere if you do a search.

VITIV Coupe

I took the car out for a drive and the gauge came off (the spiked at over 240 spot) but came back to about 230 and If I hammer on the gas it would fluctuate back and forth from 140-240 and all over the place. I know its not my sending unit, I do have power to the gauge and the proper ground so I took the gauge out of the dash. What I found is the one prong is loose, so I tried to tighten the small screw up and it would only tighten so much and then strip, It wouldn't tighten any more so the prong is basically loose. Can I put a larger screw in it to make it tight or does the end of the original screw touch something inside the casing to give you a proper reading? Or do I need a new gauge, I hope not. I believe the loose prong attaches to the black/pink wire. 64 coupe-327/365, 4 speed.

Pilot Dan

I would try screwing it in as tight as you can then put a dab of JB weld over the screw head and connector to the backing plate. The electrical contact is through the screw and connector , it should work if the gage is not broken. Worth a try before you spring for a new gage. Pilot Dan

leif.anderson93

I would think you could buy the next gauge (diameter) of screw in the same length and that would fix you right up. Loews or Home Depot.

VITIV Coupe

That's what I was thinking also. Its worth a try. I'll hit Lowes in the morning and report back, thanks.

Pilot Dan

Normally, I would agree with you but this is not a blind hole, there is an electrical connection there and I personally would not want to risk breaking the tiny winding wire when the bigger screw catches. You may end up with a tight connection, but you may also ruin the gage. Hence, the suggestion to re use the old screw with JB weld. Let us know how you make out.

VITIV Coupe

I took the old screw and prong out and put a dab of red loctite just under the prong (not touching the prong but a couple of threads down and to about half the length of the screw). That way the last half of the screw is all clean. I have had it assembled for about 5 hours now and seems to be tight. When I hook it up tomorrow morning, I'll know if it holds for good. Fingers crossed.

63redvette

Those of us who are troubleshooting our temp gauges today will be anxiously awaiting your post tomorrow. I replaced my old thermostat and temp sensor already and the gauge is still dead. grrrr

VITIV Coupe

I put the temperature gauge back in the cluster, button it all up and at the same time just for good measure, ran a ground wire from the bottom of the gauge cluster to a bolt on the cross member behind the radio. Fired it up and low and behold the gauge works, what a relief. I didn't want to go under that dash again, I'm getting to old to go into all them contortions just to get a few screws attached. lol. Its a good thing I ran that extra ground, now all my dash lights are a lot brighter also. Man, I am so happy. I love it when things work out. Thank you all for your input. I really appreciate it.
"Just warming up"