I have a question... Can the upper and lower idler pullies be interchanged? I have what I thought was a bad upper idler pulley, so I bought another one off of Ebay. Turns out it was the lower idler pulley, and it looked different than the upper, but it had same OD, so I said screw it and put the new upper pulley where the lower pulley went. Will my engine explode now? Jason