VCCA Home Forums TECHNICAL - 1945 AND NEWER 1955-1957 1957 Chevy Temperature Gauge Problem

Hi,

I have a '57 Bel Air Sedan that the temp gauge quit working in. I replaced the sending unit and it still doesn't work. I'm assuming it's the gauge. Is that the only two things that could be the culprit, or is there something in the wiring that can go bad? Is there any way to test the gauge??? If I take the gauge out, and assuming the old sending unit is still good, is it possible to stick the sending unit in some hot water and see if the gauge rises??? Is there any electricity going to the gauge other than for the lights? Sorry for all the questions, but I would really like to test the gauge before I spend the cash for a new one. If anyone around has a used one they are willing to part with, my e-mail is 4schells@gmail.com. I have posted this in the want ads also. Thanks for your time.

Randy

If you used a sealant or teflon tape on the sending unit threads it will be insulated from the manifold/engine and not be grounded. Gauge will not work.
There is a proceedure for checking the dash unit in the shop manual....do you have one?
I have a new dash unit if needed.

Well, I did use teflon tape. If I hook a battery cable to the negative post on my battery and hook the other to the sending unit, would that provide a ground? I guess it should. I should then be able to start the car and see if the gauge works. I believe I do have a repair manual, but I will double check to make sure that's what it is. I'll keep that in mind, Chev Nut, about the dash unit. It will take me a few days to get to it, but I'll keep you posted. Work can sure get in the way of more important things.

Randy

**UPDATE**

Well, I took the teflon tape off of the sending unit and re-installed it. I took my 12V testor and hooked it to the positive post on the battery and when I touched the tester to the sending unit, the lightbulb lit up, so the unit is definitely grounded. I then took the tester and hooked the positive side to the right side stud (brownish wire hooked to it) on the back of the gauge (left side if you're sitting in the car facing the gauge) and the ground side to the other stud with the green wire hooked to it. When I turned the ignition on, the tester lit up, so it is getting power to the gauge. So I figured I would take the gauge out. Well, when I got it out, the panel that the studs are on was broken off of the back of the gauge. There is what looks like a copper rivet that attaches it to the gauge, and that is broke. There are also two coils of real fine wire, one copper and the other green that looks like they are supposed to be soldered to the two tabs on the panel,and they were pulled apart. I did notice that the gauge seemed to be tipped back in the instrument panel, so I'm thinking the copper stud broke, the gauge tipped back, and the wires broke off of the tabs. I'm not sure what caused the rivet to break, but it was definitely broken. Here are some pictures:





So, bottom line is I guess I need a new gauge. If anyone has one, let me know. Thanks.

Randy

Try soldering the wires back on the tabs and see what happens.