'62 Temp. guage?

[David K.]

Ok, have a '62, all rebuilt drive train(327/250), restored guages, new wiring harness and wired according to the book. Now, I find that the book is wrong, so I now understand why my battery guage reads discharge. But, my temp. guage is always slowly climbing. I have a new Dewitt radiator and restored water pump. I did use the old temp. sending unit, since the last time I ran the car(1992) it appeared to be accurate. I did install it with teflon tape, to seal it. When idling, the thermal temp. gun shows that the thermostat is opening and closing and that the temp is holding a constant temp. But, the guage keeps going up until I allow the engine to cool down. Is this a guage problem? Sending unit problem? Wiring issue? I am currently stumped.

[Dennis C.]

'62 Temp. guage?

For starters, I'd get rid of the teflon tape and then check the reading/s. The tape can act as an insulator and play havoc with accurate readings. Best, Dennis

[David K.]

Re: '62 Temp. guage?

Thanks for the reply. Do you use any sealant at all? Like pipe dope or just rely on the fit?

[Dennis C.]

'62 Temp. guage?

In theory, the tapered pipe thread normally does not use sealant in OEM applications. I normally sneak a very little paste type sealer on the fitting and have not had any problems (leaking or gauge readings) with that approach.

[David K.]

Re: '62 Temp. guage?

Ok, thanks. I will give it a try.

[John H.]

Re: '62 Temp. guage?

Any effect from sealant degrading the ground path from the sending unit to the intake manifold would make the gauge read LOWER, not hotter. Pipe threads seal from mechanical interference of razor-sharp threads, and I doubt if teflon tape or paste has any effect on grounding at all.

[David K.]

Re: '62 Temp. guage?

Well, any clue as what is causing this temp. guage to keep on climbing? As I mentioned earlier, the thermal gun shows the engine to be steady and you can tell by the gun when the thermostat open and closes. I have not been to the car to change the wiring on the battery guage, which is wired wrong. It just seems as of the guage just keeps climbing as the engine warms and doesn't return to a lower temp. until the engine is cold. Would a bad sending unit cause this? Is there a way to check it? I understand that many of the non-original sending units do not read accurately, in these cars.

[John H.]

Re: '62 Temp. guage?

The sending unit may have died during its 16-year "sleep"; that behavior certainly isn't normal - at least you know it's unrelated to what's really going on in the cooling system. If you disconnect the wire at the sender and the gauge pegs cold, and if you ground the connector and the gauge pegs hot, you know the gauge is OK.

[Joe C.]

Re: '62 Temp. guage?

Any effect from sealant degrading the ground path from the sending unit to the intake manifold would make the gauge read LOWER, not hotter. Pipe threads seal from mechanical interference of razor-sharp threads, and I doubt if teflon tape or paste has any effect on grounding at all.

Thanks John. I'm glad that somebody "in the know" has finally provided the right answer regarding this "voodoo" theory.

Joe