My MB mechanic wants to replace the belt tensioner for a healthy sum of cash I may say. What is it and do I need to have it done? Im new to MB and purchased a 1992 190e 2.3 with 90,000 miles. I took it to a German imports specialist to have it checked out. He has a nice long list of things to make the car perfect again for about 3200 bucks. I cant afford to have it all done at once and Im no where near mechanical. This tensioner was priority number two on the list. The car runs great, can this wait?