Audi S5 Belt Drive Issues: Tensioner Trouble Alert

I faced a similar issue with my 2015 S4 last winter. I have some experience working on engines, mainly basic maintenance, but this needed professional help. The serpentine belt was making a distinct squeal during cold starts, which got worse over time. The timing belt tensioner pulley was failing, causing improper belt tension and affecting the handover mechanism. This is actually a common wear item on these engines. I took it to a workshop where they confirmed the diagnosis and replaced both the tensioner pulley and the idler pulley as a preventive measure. The total repair came to 455 Euro, including parts and labor. They strongly advised against driving with these symptoms, as a failing belt system can lead to serious engine damage if the timing belt fails. Before I can provide more specific advice, could you share: Current mileage on your S5, How long have you noticed the belt squeal, Does the noise change with engine speed, Have you noticed any changes in engine performance These details would help determine if your issue matches what I experienced and whether immediate attention is needed.

Last service was at 110000 KM, just 414 KM ago. The serpentine belt squeal started about 2 weeks ago and definitely gets louder when engine RPMs increase. No major changes in engine performance yet, but the belt drive noise is concerning. The automobile maintenance schedule in my manual doesnt mention belt tensioner replacement until 120000 KM, but this seems premature. I scheduled an emergency appointment with my mechanic for tomorrow. Not worth risking engine damage from a potentially failed timing belt. Thanks for confirming my suspicions about the belt tensioner and sharing repair costs. Will report back after the diagnosis.

Thanks for the mileage details. Your symptoms match exactly what I experienced with my S4, the increasing noise with RPM is a classic sign of belt tensioner issues. Even though the automobile maintenance schedule suggests 120000 KM, these components can wear prematurely depending on driving conditions. Smart move booking an emergency appointment. When my tensioner pulley failed, the repair shop found metal shavings inside, clear evidence it was deteriorating. The engine noise from the failing tensioner actually masked a worn idler pulley too, which is why I recommend getting both checked. This kind of preventive maintenance might seem costly now, but its far cheaper than dealing with engine damage from a failed timing belt. For comparison, my repair included: Belt tensioner: 180 Euro, Idler pulley: 95 Euro, New serpentine belt: 65 Euro, Labor: 115 Euro Keep us posted on what your mechanic finds. Based on the symptoms, I suspect youll be looking at a similar repair scope to what I needed.

Thanks everyone for the detailed feedback. After getting it checked today, turns out you were spot on, both the tensioner pulley and idler pulley needed replacement. The belt squeal was definitely from the failing tensioner, just as suggested. Final repair bill came to 470 Euro total: New tensioner assembly: 195 Euro, Idler pulley replacement: 90 Euro, Serpentine belt: 70 Euro, Labor: 115 Euro The mechanic showed me the old parts and there was clear wear on the bearings. Timing belt tension is now perfect and the engine noise is completely gone. No more cold start squealing either. Really glad I got this fixed before any major engine damage occurred. For anyone else experiencing similar symptoms, dont wait on getting it checked. The repair cost is much better than risking timing belt failure and potential engine problems.