help clio overheating

hi, just found you and the threads look very helpful. I have a 1993 clio, a runaround.. it is overheating it may be the gasket but before I write it off I am looking at other options... I go on a 20-30 mile trip and the water (which was full) has now run out. If I sit in traffic it overheats!. I have tried to bleed the system to no avail and it is not misfiring so I don't think it is running into the oil! Now i have always had it on hot temperature inside the car. Today I have put the temperature on cold and it did not really overheat, well it did not go over 1/2. what can i do? Do you think it could be the pump or the matrix??? Any help appreciated. I want to get this problem sorted prior to it getting really cold! And I am under the bonnet with fingerless gloves on!

Thanks

Tracy