my friend has a 83 v6 3.8l mustang. his temp gauge is malfunctioning, and we want to know if there are any easy fixes for abroken temp gauge or if this is a common problem in these models.(we've done the usual; water pump, thermostat, etc.)

 

Pull the connector off of the sending unit, shove a nail in it & ground it to the engine. Turn the key to run, if temp gauge shows full hot, replace the sending unit.