check to see that the water pump is tight and not leaking from the seal(gasket)between it and the balancer.if your model has a crossover pipe,check to be sure that is tight.grab the fan blade(engine off)and push it back and forth.if there is more than a very small amount of play,the shaft bearings may be worn.best guess,better to know you have a new water pump on 285 than to wish you did.