Temperature gauge

[regularman]

Well, I swapped the capillary tube from the donor gauge to the smiths gauge and that went smooth as silk, done in about 5 minutes. Easy soldering. After soldering it on and getting the spring cover all fastened down to the gauge, I tested it out in boiling water. The gauge went up but only about 3/4 of the way from cold to hot. I checked inside the gauge and the maximum span of the gauge is already taken up as the arm from the bourbon tube is already as far in on the movement lever as possible. I ended up moving the needle so that when cold the gauge needle is just within the white marked area for cold and when in the boiling water it is just within the white marked area for hot. For y'all that did this or have ever check the cal on your temp gauge, where did the gauge read when in boiling water? I know that boiling water mixed with antifreeze and then capped under pressure is going to go a lot hotter before it actually boils but I am just wondering what an unmolested gauge reads. I can live with this one as it is because I know it reads in the H area when its hot and as long as it is not up that high then I am good to go.

 

[Trevor Jessie]

Mine show about 210 degrees in boiling water, but it no longer goes all the way down when cold. But checked against a cheap lab thermometer it is accurate at 185 degrees. So it works for the important temps.

 

[regularman]

Mine show about 210 degrees in boiling water, but it no longer goes all the way down when cold. But checked against a cheap lab thermometer it is accurate at 185 degrees. So it works for the important temps.

Yours has actual degree marks? Mine just has a C then an N then an H which are all kinda gray area.

 

[regularman]

Oh something else. The movement can be removed from the gauge from the front. I removed the oil on to get to the temp one and on each I put a drop of 3 in 1 oil and both move much free-er and smoother. I had noticed that my oil one was kinda jumpy.

 

[regularman]

OK, trevor. You peaked my curiosity and I found a picture of the older style MGA/spridget type guage and the face is the same except that the older one has numbers on the temp face. It looks as though the 212 point on the old gauge is exactly where the H white mark range starts on the the newer kind. So I am exactly calibrated at the right place for the boiling point. I know with antifreeze and a 10psi cap that it could go higher but now I know I am good at the important point. If it doesn't go up against the stop at the cold point then so be it. I still have the full span of the N range and I like it. I imagine that the gauge has been out of cal for a long time and I am just now finding it, because with the ether pressure point being always the same for a given temp in a sealed system and the bourbon tube being untouched, it must have been off before. Any of you guys that are in mid resto of whatever might want to check your temp gauges. Just drop the bulb in some boiling water and it should read just right into the white mark for H to be in cal. I kind of wish I had the older face, but now I know and I am good to go. I got some more brass tubing already drilled out is anyone needs some for a sleeve. I used the cheap 16.99 sunpro black face gauge from advance as the donor and the capillary tube is the exact same size (within .002) as the Smiths capillary tube. I used a weller soldering gun on the 230watt range. I solder on a regular basis with electrical stuff and I also had worked with soldering tubing before so this was not hard at all. after sanding with some fine paper and wiping everything down good with a rag and some rubbing alcohol (including the solder to be used) I put a spot of rosin flux on each piece to be soldered and tinned it and then soldered the sleeve onto the smith's capillary and then before I cut the sunpro one I cut the spring cover and pulled it back as far as I dared and then sanded tinned and soldered a small brass washer right there to hold the spring cover back out of the way. Then I sanded and tinned a spot on the sunpro capillary. Then notched it with a file about 1/2 inch down from there and broke the tube and slipped it inside the sleeve and then soldered it up. With a clean joint and some flux the joint was great the first time, then I removed the brass washer I had soldered on to keep the spring cover back and let it come up over the sleeve. The cover was short of reaching all the way to the gauge by an inch but I stretched it a bit in several places and it fit good. Then 3 layers of shrink wrap to hold the spring to the gauge good and done. I used a salt water/ice bath for keeping the bulb cold. If anyone else is going to do this, let me know if I can help, or I can do it for you when I have time if you send it to me.

 

[jlaird]

Man, what talant, good on ya.

 

[regularman]

Man, what talant, good on ya.

Ha, even a blind squirrel finds an acorn every once in a while :wink: I am trying to figure out a way to check the cal on my oil before I put it back in as there is some adjustment on it if it is off.

 

[Billm]

Hook it up to your air compressor (after the regulator) and compare as you crank your regulator up and down. Worked for me.
Bill

 

[regularman]

Hook it up to your air compressor (after the regulator) and compare as you crank your regulator up and down. Worked for me.
Bill

Hey man, good idea. I will go sort through my fittings and see if I have something that will work out for that.

 

[jlaird]

Exactly, I just taped mine on with some Duct tape. Checked out good.

 

[dklawson]

I use my air compressor, "T" fitting, and known good gauge to calibrate oil pressure gauges. Like you, I found the movement a little jerky before cleaning and applying a little thin oil.

On the first capillary temp gauge I repaired I had no problem getting it set to read 212o (just at the white on "H") when I put the bulb in boiling water. My gauge also showed a non-zero amount on face when cold. I tinkered quite a bit moving the pinion gear and then re-calibrating several times to get the gauge to read the way I wanted it to. Eventually I got it so it read accurately from about 165o to 212o and gave up. It still wasn't all the way to the left when cold but I really wasn't concerned with temperatures below 165o anyway.

When it was all said and done, I remembered that the gauge had not been sitting all the way to the left when I started the transplant. Perhaps something was already messed up with the calibration from a previous owner.

 

[regularman]

OK, gauge all in and done. One more thing that I had to do. The bulb endon the new capillary was a little longer than the original and went in and hit something before making a good seal. I lost much new antifreeze and religion in finding this out. I ended up putting a ferrel off of a 3/8 brass pipe fitting over the bulb before putting it in and then tightening the nut and it sealed it off good. Ran the motor for a while just to test it out. I also installed a volt meter beside my ammeter under the dash on the passenger side. I am getting there.

 

[regularman]

Oh and I checked my oil pressure gauge out and through two different gauges on two different regulators the gauge was within 3psi, good enough for me.

 

[dklawson]

That's great!

The bottoming out of the bulb in the head isn't unusual even without the transplant. There is an adapter piece available from sources like Mini Mani (item #11K2846 for $13) that will reposition the bulb further out. Your ferrule solution is very clever and I'll remember it for the future.