The pulley fitted to the front of the crankshaft is also a vibration damper: a rubber insert connects the outer ring to the inner one. The rubber ages and hardens, in the end it separates, and then the outer ring slips. The rubber ring can also fall out into the engine bay. This is one of the known faults of these engines, mainly on the early production units. The first sign is unusual vibration at idle, then a wobbling, clacking noise from the engine bay. If the pulley slips, it takes the belt drive with it and can touch the oil pan and the front cover. Those then have to be replaced as well, and the material cost alone is around 750 euro. Prevention is simple: it is worth checking the part number of the pulley and replacing an old-specification one before it comes apart while driving. The fault comes up above 170,000 km, but on the early units sooner as well.