You could try removing the gauge and setting the bulb into a pan of 200 degree water. If the gauge needle doesn't move (and assuming that bulb has been installed correctly into the head), the gauge isn't working. If you're not having overheating problems, it may be just a temp gauge issue. You do know a 180 thermostat sets a floor and not a ceiling on engine temperature, yes? Also in the winter in Rhode Island a 180 degree thermostat probably will work in very small increments...I assume when you say you can't see the t-stat open you are saying you don't see water coming out of the top hose, yes? Without some sort of special camera, I don't think you can actually see the thermostat working when it is installed and you also should know (as I'm sure you do) that at 180 degrees, a 180 t-stat will just begin to crack open. It won't be fully open until around 200 or a bit more. At 180 the t-stat may be only open by 1/16 inch or so, therefore the amount of water passing through will be small. If you want to test this, get a pan of water and a candy thermometer. Heat the water to 180, set your thermostat in and see what it does...if your temp at the top hose is around 160 or so, then the thermostat will just be dribbling water through the air bleed (jiggle valve) hole.
Good luck.
