29th of June 2016 ... Number of Responses 1 --

I just changed the serpentine belt on my 01 Saturn SC2. A week later, I get a diesel rattle at idle with engine under load - in drive and AC running. What can be causing this?

This is a common problem with the Saturn S series. Most likely that the tensioner is hitting its stop given that this occurred after a belt change. The original factory belt was 77.8 inches long and most after market belts are 78 inches long. The original belt tensioner also was filled with fluid which avoided the rattle. First option, see if the pulley wheel for the idler is 100mm in diameter and that the tensioner pulley wheel is 90mm in diameter. At some point, some of the tensioners only had a 76mm pulley wheel on them. As car gets older and parts are swapped out, then pulley wheels of different diameters can end up getting used which causes belt issues. If either of your pulley wheels are smaller, replace them with the larger size. Note that it will be tougher to put the belt on and best to slip it over the idler pulley. Use a 14mm wrench to undo bolts. Autozone has the parts - 100mm idler duralast 231026, and replacement tensioner pulley wheel - 90mm duralast 231099 (equivalent to ac delco 38010) (note Autozone will say the tensioner pulley does not fit car but it does). Second option would be to locate the factory tensioner and belt - some online GM parts stores can supply it such as gmpartsdirect.com or gmpartsnow.com.