I have a 1997 nissan 200sx. the other night i noticed a faint smell of plastic melting or something similar. a day later my car overheated. i let it sit for the night and filled up the radiator with water and drove it around a little bit and noticed the same smell, although with no overheating. any pointers? i'm going to flush and change the coolant, but someone told me this wasn't necessary. if anyone could give me advice it would be much appreciated.