I have a 94 Saturn that seems to have a random over heating problems. Out of the blue the engine just starts to over heat, usually while idling, some times while driving. It might go weeks and not have a problem then out of the blue starts to over heat. Is goes from normal which the needle stays in the 1st 1/4 marking and then jumps to the last 3/4 marking.. The water pump seems to be fine, it's not leaking any where. The fluid seems to be good and full. The A/C is always off and the radiator fan seems to run like normal when it begins to over heat. It over heats for about 5 minutes then goes down to normal and usually stays there for a couple of days..
Does any one have any suggestions as to what the problem might be? I am planning on changing the thermostat and flushing the radiator to see if that solves the problem..
Thanks..