My 2 5/8" Stewart Warner mechanical temp gauge was reading 35 degrees low. This is how I corrected it. Photo #1&2 Use paint can opener to carefully uncrimp bezel. #3 Unscrew nut to disassemble gauge. #4 Can of water, heated with torch. accurate mercury thermometer (could use any known thermometer) Infrared etc. #5 Heat water,stir to equalize temp. #6 Bend kink area only with 2 needle nose pliers , to adjust gauge to thermometer reading. BE DELICATE, IT DOESN'T TAKE MUCH TO MOVE NEEDLE. increasing kink moves needle higher up scale. #7 After the gauge is calibrated reassemble and roll bezel back with box wrench. You can make a jig to hold gauge in lathe and tailstock and roll bezel on with a ball bearing on lathe tool. Ago
Thank you sir! I have a couple of older temp gauges that no longer read correctly, will have to try this on them. Does any one know what causes them to read incorrectly? I recently picked up a NOS Stewart Warner from 62 and it is off by 10 degrees.
I've always used SW gauges in my cars since the early '60s and years ago had trouble with the accuracy of a mechanical temperature gauge. It was off 20 degrees @ 200 f. I contacted the SW rep and was told that the gauges were accurate plus or minus 10%. I sent mine to Mo-Ma in Albuquerque, 505-766-6661, for calibration. Your post is interesting and very helpful. Thanks
Ago, are you a surgeon in your day job? I have a few junk S/W gauges & I'm going to try to remove & reinstall the bezel. I always heard it was a losing proposition to the layman. I'll let you know how I make out. By the way, how do you know that your gauge was reading low? Maybe that was the right temp? I've had four different gauges in my 283 (two electrics & two mechanicals) & they all showed different readings. I'd like to do what you did just to make my gauge read what I'd like it to read. Most excellent tutorial, by the way.
That's a good fix!! With a bourdon-tube gauge (that's what the mechanism in your temp meter and also the pressure gauge is called), the things which s damage them most are over-ranging (a bit hard to do with a temp. gauge, but easy to do with a pressure gauge), and getting crud into the mechanism/tube (again, temp. gauges are sealed, so can't really happen, but pressure gauges, yes.)
Fleetside, retired machinist. I have a 180 degree thermostat in my car and it never would read near that. So I took the bulb out of the manifold and layed it in a small tin can with water and a mercury thermometer and heated the water with a torch and compared the readings. You have to be delicate with gauges,( no all thumbs). I repaired a couple of gauges off early British bikes(Smiths). I have a book that shows you how to make a jig to roll the bezel back on with a lathe. and it works well. I will post it in the future. Ago
More info on gauge bezels. Here is a jig for rolling the bezels back on gauge faces. You will need a different jig for each diameter gauge. Using the paint can opener to remove bezel. That is a bearing in lathe tool holder to roll on the bezel. The lathe is rotated by hand no power. Credit for the jig goes to Graham Blighe who authored the book MAGNETIC SPEEDOMETER REPAIR. Graham's book is only about British M/C speedos. Ago
O.K., I did the lens removal thing on a mechanical water temp gauge where someone cut the line. Here are some pics. I must say that I personally found the paint can tool a bit too cumbersome, so I tried massaging it a bit smaller & sharper. It still didn't seem right to me, so I bent a small flat bladed screwdriver & that seemed to work (for me, anyway). It came off real nice..no tears or unevenness. Getting it back on was a bit more of a challenge. I tried the wrench head method, which worked fairly well, but I did end up using the screwdriver a bit to clean it up. I'm not so sure that I'd be as successful with one of the older S/W gauges (like the Wings), because I heard somewhere (maybe Travis from Morris Gauge) that the bezel is very difficult to remove & reinstall because of its inherent softness. I don't think I'll be experimenting on one of those anytime soon. Anyway, thanks for the post. Next I'll try the calibration thing. Actually, I think more than anything that being able to remove & replace the bezel will be good for cleaning those gauges that have all the dust underneath.
Grasshopper, I had to modify the paint can remover also, I mounted the paint can opener in the tool post of lathe. It worked a little better. We need a lot of patience with this stuff. Do you know someone with a lathe? The lathe fixtures for rolling the bezel back on work well. You nee one for every different dia. of bezel. Ago
I've done several bezel removals and installs by hand. Must be easier with the lathe. Slow going but worth it. You can get a piece of wood (2x4, etc) as a holding fixture and, providing you have the correct hole saw size, drill a hole to take the front edge of the bezel and hold it steady while you open or close the edge from the back side. Gauge goes face down into the hole - helps to protect the glass too...
Gotta love the HAMB! You have an issue, go turn on the computer to see if anyone else faced the same thing, and, WALA!, there it is. I bought some of the current Wings gauges (Hecho en Mexico) and gonna run two mechanical temps, one for each side of the flathead. I put in 180* thermostats. Finally got the old motor started recently and both new gauges read 150 to 155. I just pulled off an upper hose to verify my thermostats and it is stamped 180. So both read the same low temp, apparently. At least they're standardized. Knowing this, I think I may just leave them be. I know that I don't have the steady hand required to do this sort of work.
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