So I bought a 1998 GT with about 88,500 miles on it about two months ago, everything was great for the first two weeks or so. I eventually began to notice a slight coolant leak coming from a small crack in the thermostat housing. I understand that it is a common failure point on these cars as the entire intake manifold is made of plastic, but being ignorant to that knowledge at the time I just decided to try to seal it using JB weld. I let it harden over night, and it seemed fine, but on my commute the next morning i guess the pressure built up or something and it basicallly shattered a big hole in the housing spraying coolant everywhere, i pulled over and took it home, luckily i wasnt very far and was able to get it home without overheating. I went to the junkyard and got a replacement manifold with the aluminum housing off of a crown vic, everything fit pretty well, didnt have to really move anything around but when i got everything back together i noticed the coolant temp guage wouldnt work, it stays below the cold mark all the time. The car seems to run well, i havent had any issues with it, no check engine lights or anything and before anyone asks i did put the thermostat back in and i replaced one of the coolant temp sensors, what could be the problem here???