Chain guide failure is almost always due to tensioner failure. Loose chain means slop. The pretension spring does almost nothing it's all up to oil pressure. The tensioner force from oil pressure is many times the force from the spring and once the tensioner wears the force can drop 50-70% and you won't know until you hear the rattle or the chain derails and bends all your valves

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)