How can I fix rumbling noise?

I drive a 2001 Suzuki Swift, AT with electronic power steering. I get this rumbling noise in the front,when driving off road. My mechanic says it has something to do with the steering arm and he advised against meddling with it lest i lose my power steering. I would really appreciate a second opinion. The engine is also noisy when idling or at low speeds unlike other car models which are very quiet. Thanks