One problem related to steering noise has been reported for the 2008 Mercedes Benz ML350. The most recently reported issues are listed below.
The powersteering pump went bad at 72,000. Started to make noise and hard to steer at highway speeds. It took my by surprise and almost crashed. Drove the car to the dealership and was quoted 2,500 to fix. Its a shame for a mb to have powersteering issues at 70k miles.