you can check the temp gauge easily if you can get some one to help you try this,take the temp sender wire off of the sender and have someone turn the key to the on position and take a wire and ground it to the batt or engine and then touch it to the sendor wire and tell the other person to watch the gauge and DON'T keep it there for any longer then three or four seconds. if the gauge goes up to the hot area of the gauge or close to it then the gauge inside is ok and you need to replace the sender, if it don't then it's a good chance that the gauge it self is bad or maybe the wiring going to the gaugegood luck