Re: Engine Temperature Guage Inoperative - Where to Start?

Posted by David Grubbs On 2013/1/14 15:33:11

Having repaired the temp gauge on my 39 120 a year or so ago, and a similar gauge on a 34 Chevy last week, replacing the tube is fairly easy. You will need to get a new mechanical gauge from Napa as a donor for the tubing, plus about 1 to 2" of a very small diameter copper tube to connect the old tube to the new. This is the easy part.

You will also need a very very small drill bit and a pin vise to hold it. When you cut the tubing it will invariably crimp the tube so that no gas can flow thru the junction. After you cut it, you need to take the pin vise and tiny (much smaller than 1/16") and open up the end of the tube. I had to go to a machinist friend of mine in order to get one of these little drills. Don't bother with the ones from Harbor Freight, as they snap easily. Ask me how I know!

You can do this work in an evening, but it the gauge itself has a problem, you still haven't solved the problem. The Packard gauge worked fine after it was repaired, but the Chevy one would only go to 190 when immersed in boiling water since there was something wrong in the mechanism of the gauge. Moral, of the story, it is probably a good idea to send it into someone who can repair both the tube and the gauge. But it was fun fixing the Packard gauge!