RS6 Belt Tensioner Causing Acceleration Squeal

Had the same issue on my 2010 Audi S6 last season. The serpentine belt squeal during cold starts and acceleration is a classic symptom of a failing belt tensioner assembly. The tensioner pulley was not maintaining proper belt tension, causing the belt to slip. The automobile maintenance revealed both the belt tensioner and serpentine belt needed replacement. It turned into a more serious repair than initially expected because the worn tensioner had caused uneven wear on other pulleys in the belt drive system. The repair involved: Replacing the belt tensioner unit, Installing a new serpentine belt, Inspecting and cleaning all pulley grooves, Testing belt alignment and tension This is not a repair to postpone, as a failed serpentine belt can leave you stranded and potentially damage other engine components. The tensioner pulley bearing usually fails gradually, but once you hear consistent belt squeal, immediate attention is needed. Would strongly recommend having it checked soon, as these symptoms match exactly what led to my tensioner failure.

Thanks for sharing your experience. Your description of the tensioner pulley issue matches my situation perfectly. The belt drive system squealing has gotten more noticeable in the past week, especially during cold starts. Got it scheduled for inspection tomorrow, as I agree this needs immediate attention for proper engine performance. The symptoms are too similar to ignore, and I definitely want to avoid any cascade of problems from a worn belt tensioner. Did you remember roughly how much the total repair ended up costing? Also curious if youve had any related issues pop up since the fix?

Since getting the repair done on my S6, everything has been running perfectly with zero belt squeal or tensioner issues. The total came to 455 Euro for replacing the bad belt tensioner, which was exactly what the mechanic diagnosed as the root cause. The service fixed all symptoms completely, no more noise during cold starts or acceleration. The serpentine belt is now maintaining proper tension and running smoothly through all the idler pulleys. It was definitely worth addressing promptly before it could cause additional wear on other components. This kind of timing belt system repair tends to resolve the problem completely when done right. Have not needed any follow-up work in the 8 months since getting it fixed.

Thanks for the detailed information. After taking your advice, I took my RS6 to the mechanic yesterday. The diagnosis confirmed exactly what you described, a failing tensioner pulley causing the serpentine belt issues. The repair bill came to 520 Euro total, including: New belt tensioner assembly, Fresh serpentine belt, Labor costs The mechanic showed me how worn the old tensioner had become, with visible bearing damage affecting the belt drive system. They also found slight wear on one idler pulley but said it was still within spec. After the repair, the engine performance is noticeably smoother. No more squealing on startup or during acceleration. Really glad I addressed this before the belt could fail completely. The whole process took about 3 hours, and the shop did a great job explaining everything they found and fixed. Will definitely keep a closer eye on the belt drive system during future maintenance checks to catch any issues early.