I have a 87 Camaro with a 305 4Barol and I wanted to know what Sensors are on the neck that where the thermostat is. I replaced one but the other is melted and there is no wire going to is so I dont know what it is. Thats how I bought it also for some reson when my car starts to overheat the fan wont come on so i tryed getting a wire strait to the fan to see if it works and it dose. Please Help!!!

The tree with all the vacuum lines is a valve that opens once the car reaches operating temperature (195° F). It is there because you don't want EGR and other smog controls functioning on a stone cold engine. It has no effect on overheating nor does it control your fans (they are controlled a thermal switch on radiator that senses the tube temperature).

Larger Dave