1941 Cadillac Series 63 Temperature Gauge

[J. Russo]

I removed my dash yesterday for the purpose of installing a new wiring harness. The only issue I have is removing the temperature sending wire from the gauge. I don't want to do anything that might break it. Please see attached photos. It doesn't seem to simply pull out of the gauge end.

Thank you

[35-709]

That is not a wire!  Don't pull on it, don't put any sharp bends in it!  That is a bourdon tube gauge and is one piece from the engine to the gauge, you will have to remove the gauge itself and GENTLY place the unit aside with some support so you don't break/fracture that line.  If you DO break it, it can be repaired, usually by a professional instrument rebuild service.
Gauges like that are still made and used today, mostly in old car restorations and hot rods, my Auburn Speedster will have a new bourdon tube water temperature gauge.

[35-709]

From:  http://www.secondchancegarage.com/public/653.cfm

How Automotive Temperature Gauges Work
There are basically two types of temperature gauges, electric and mechanical. Today's cars use electrical gauges but not too many years ago many used mechanical gauges that operated with a Bourdon Tube.

The Bourdon Tube
A Bourdon Tube is a thin metal â€" usually brass or copper â€" tube that is filled with an easily vaporized fluid, typically alcohol. It is sealed at both ends. At the gauge end it is formed into a circle or spiral with its end attached to the indicating needle by some form of linkage. The other end is fitted to a water-tight connector that is in direct contact with the coolant in the engine.

As the coolant warms up the alcohol in the Bourdon tube expands. The expansion transfers its force to the coiled end of the tube inside the gauge. As the coil or spiral unwinds it pulls the linkage on the needle, which in turn shows a temperature reading on the gauge face. The gauges are calibrated during the manufacturing stage and are not adjustable afterward.

Since the Bourdon Tube design is purely mechanical the gauge will continue to read some temperature level even after the engine is shut off. As the engine cools the gauge's needle will return to its rest position.

Bourdon Tube gauges aren't used anymore (yes they are, but not on modern production cars as a rule) because of cost and convenience factors. The tubes are delicate and must be carefully routed from the dash to the appropriate fitting on the engine. The gauges themselves are far more expensive than electric or electronic gauges and if the tube is kinked or split the entire gauge assembly must be replaced (not so, they can be repaired as opposed to replaced).

[harry s]

John, Your gauge looks like a supplemental old style from what can be seen. Most all 41s I've seen have an electrical gauge. Was the face of your gauge in the original dash cluster? Can you post a picture of the face?     Harry

[J. Russo]

Mr. Newcombe is correct. It is not a wire. I apologize for the incorrect phrasology.  The tube is in good shape with no kinks. However, I'm not sure it works properly as I don't believe I've ever seen the needle move.

If it no longer works can I easily replace it with a more modern sensor? Is there any risk to the engine connection if I remove it?

Harry, I added a pic of the facing and the cover.

Thanks

[harry s]

John, The gauge you have can be repaired or calibrated but in most cases you have to send the entire unit out to someone that specializes in repairing them. This can be expensive. I'm going to go out on a limb and say 41s originally came with electric temp gauges. If you are installing a wiring harness made to factory specs there should be a wire at the engine for the sensor and two at the gauge. You can go back to the electric by sourcing a sensor which are reproduced and a gauge for your cluster.      Harry

[J. Russo]

Thanks everyone very much.