Pulled out the engine about a week ago and noticed yesterday a sensor on the passenger side of the block that bolts to the coolant passage. The weird thing is that the wire coming out of it was just connected to one of the starter bolts. I doubt it was doing much good because when I pulled it out, no coolant came out since the block was so full of coolant residue (I had to poke a screwdriver through the hole to let the coolant come out). Anyway, what is this sensor and where is it supposed to connect? so that I can buy a new one and connect it correctly.