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Mechanical Temp Gauge Rebuild


Friartuck

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Trying to rebuild a mechanical temp gauge. The hardware (bulb, capillary tubing and gauge) has been inspected and working, in essence no leaks. What is the fluid used in the bulb? Methyl Alcohol, Ether or a derivitive of Ether like dioxane??

For this application, would you want a lower boiling point or a high one? Some like Methyl Alcohol has a boiling point of 66 degrees C where dioxane has a point in excess of 300 degrees C. Would think a high boiling point would be better.

Could this be as simple as just using the better grade starting fluid which uses diethyl ether? But diethyl ether has a boilding point of only 35 degrees C.

Have seen the article on the Plymouth site, but doesn't say where to purchase the fluid.

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You are probably referring to the article on my site. The reason I don't list where to get fluid is because you are getting it in the bulb from the donor gauge.

If you are attempting to put ether back into an existing bulb, the I suspect that you would want one with the lower boiling point. Using your numbers that would be the diethyl ether with a boiling point of 35C. As the ether attempts to boil it raises the pressure in the closed system which then increases the boiling point. The gauge simply measures the pressure in the capillary.

If you select a fluid that does not boil until 300C then you will not read any pressure until the engine gets over 300C. I don't know about your car, but that is way above the 80 to 90C that I would prefer my engine to run at. :)

By using a fluid with a boiling point of 35C you will actually start seeing you temperature gauge needle start to move when the engine is around 35C. And that seems about right to me.

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Ply33,

Yes, I was referring to your article, but didn't know it existed until after the fact. I had a newer style donor gauge with bulb and capillary tubing, but it didn't seem to work after the modification. The main mistake was not submersing the bulb in ice water/salt solution. On mine, I'm able to solder the gauge side directly to the threaded connector. After that failure, I tried using(adding) Methyl Alcohol, but that has a boiling point at about 66 degrees C. Your mentioning the diethyl ether (35 C point) now makes sense as the 66 degree point for Methyl seemed way too high for the results I was getting. I had to really heat the bulb to get any reasonable results, hence why I declared it a failure. So this seems to be one of the questions answered. Now where to acquire diethyl ether. Suppose I could try the starter fluid route, but several web sites indicate premium grade starter fluid has a 40-50 percent diethyl mixed with other petroleum distillants. I can use a hyperdermic needle to refill if I can find the right stuff.

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  • 2 weeks later...

Friartuck

''Diethyl ether, analytical grade, Ph Eur, USP, ACS, stabilized with approx. 7 ppm of

2,6-Di-tert-butyl-4-methylphenol (BHT) ''

This is a quote from a Jaguar forum re the filling of a temp. guages. I hope it helps.

Art

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