I recently had an engine rattling noise in my 2010 Altima that I just couldn't figure out. I took it to 3 shops and although 1 shop came close to diagnosing the problem by recomending changing the serpentine belt which turned out to be the problem they also wanted to replace the motor mounts. The best thing was the cost of replacing the belt was half of the other shop's written estimate. I appreciate their honesty and not trying to stick me with un-needed costly repairs.