Noisy wipers are often caused by old wiper blades where the rubber blade is permanently bent over because of age. If it is the motor then the way to detect it is to pull the blade away from the rear screen and leave it in the servicing position - then operate the wiper switch. If it still makes the noise you describe then it's the motor. If it operates quietly while the blade is in the air then it's the blade at fault. In that case fit a new blade. I generally replace my rear blade every year or two.
ChicksFan, April 2014
