Hi did you know if you check the fan when the engine is running it stings?
i would also suggest checking the water pump - it has been know for some of the propellor vanes to come off thus making it very poor at circulating the coolant which to stop the engine over heating should also be the correct mix as not only does it prevent frost damage it is also as the names says a summer coolant i have found 50/50 is the best mix
cheers
Steve