Hi My 98 z3 recently starting overheating. It will run fine for first fifteen minutes or so then and temp will be right where it is suppose to be then in a minute or too needle will go all the way up. I am pretty sure it has to be either the thermostat or the waterpump. But is there any way to test which or am I better off just replacing both the car does have 92 k on it. Thanks for the responses.