We had recommended that this customer replace their accessory belt and belt tensioner because there was a noise coming from the tensioner and there was irregular belt wear. Unfortunately, the customer declined these repairs and returned several months later on a tow truck. The belt did fail. On BMW 3 series and 5 series cars from 2004-2016 with N52 or N54 engines, there is a unique problem where the belts get sucked through the crank seal and into the oil pan. If the belt is just changed and the oil pan is not inspected there is a strong probability that part of the belt has been sucked into the oil pan, will make its way to the oil pump pickup, causing oil starvation to the rods, ultimately damaging the rod bearings, crankshaft and rods and leading to engine failure. This is a known problem with BMW 323, 523, Z4 X3, 525, 325, 328 128, 630 and X5 vehicles with the N52 or N54 engine.