mk2 dash engine temperature sensor

iv put my engine back together and put this to the tab on the right hand side of the cylinder head but the dial goes right off the scale within 10 seconds of startup. presuming this is the wrong sensor?  where should it go and what does the one i have currently got it on do?

its a 1.8 gu engine 1989

are you hooking it up to thew large black sensor? if so thats oil temp. it should go to the small black colar sensor in one of the coolant flanges, front or side depending on the age of car.