Does the radiator fan alway's kick in ? Could be a faulty thermo switch which is on the side of the radiator with two wire's going to it, which sense's the water temp to start the fan. Try taking it out and giving it a good clean when the engine is cold,or you can renew it for a few quid. You will have to top up your water and run the engine with the filler cap off for 10min,s to get rid of any trapped air. It,s not a hard job but if your unsure get someone that know,s abit about car's to help.
paul
May 2008