My 96 m3 has recently started to overheat a little. It only happens after i have been driving for about half an hour. It seems to start to overheat when i am crusing in 4th gear or when i am idling. The weird thing is that it never gets to the 3/4 line. It always gets almost to the 3/4 line and then stays there or goes back to normal. What could this be. Am I hurting my car. I have taken it to the dealer but they couldn't duplicate. I am afraid that if i take it back they are going to say that it is normal because it is not above the 3/4 line.