VW Fox Timing Belt Squeal Signals Bad Tensioner

I had a very similar issue with a VW Polo 2008 1.2L gasoline engine. With some experience working on VW engines, I can tell you that belt squeal during startup is often a serious warning sign that needs immediate attention. In my case, the serpentine belt was causing the noise, and it turned out the idler pulley was completely worn out. The tensioner assembly was also damaged, which explained why the belt had become loose. What started as an annoying squeal could have led to complete belt failure. The repair included: New serpentine belt, Replacement of idler pulley, New belt tensioner, Full inspection of timing belt components Total cost was 455€ for parts and labor. While expensive, it was worth fixing properly as a failing belt system can cause major engine damage. Before suggesting specific solutions for your Fox, could you share: Current mileage, How long has the squeal been present, Whether the noise changes with engine speed, If there are any other unusual engine noises, When was the last timing belt service done This information would help determine if your issue is similar to what I experienced and whether additional components might need inspection.

Thanks for sharing your experience. My last service was 3 months ago and everything was fine then. The belt squeal only started this morning and definitely gets worse when revving the engine. The noise is most noticeable during cold starts and seems to improve slightly after the engine warms up. I have not noticed any other unusual engine performance issues or sounds. Checking our service records, the timing belt inspection was done during that service and mentioned to be in good condition. The fact that both the tensioner and idler pulley needed replacement in your case makes me think I should get this checked soon to prevent more extensive damage to the belt drive system.

Thanks for those details. Your symptoms do sound very familiar, my Polo showed the exact same behavior before things got worse. The fact that your belt squeal improves after warm-up but worsens with revving is a classic sign of tensioner issues, very similar to what I experienced. The 3-month timeframe since your last service is interesting. While the belt looked good then, the tensioner pulley can deteriorate quite rapidly once it starts failing. In my case, the engine performance stayed normal until the belt tensioner completely gave out. Given how closely your symptoms match my experience, I would strongly recommend getting it checked within the next few days. When my tensioner failed, it quickly led to belt misalignment and increased wear. The repair ended up being more expensive because I waited too long. If the parts are similar to what I needed, you might be looking at around 350€-400€ for a complete fix. While getting just the tensioner replaced might seem tempting, replacing the full assembly (including the idler pulley) is usually the smarter long-term solution for maintaining proper belt drive operation.

Thank you everyone for the detailed responses. After hearing about these similar experiences, especially with the same engine type, I've decided to book a workshop appointment for tomorrow morning. The progressive nature of the belt squeal and its response to engine temperature changes has me convinced this needs immediate attention. Given how the symptoms match with a failing belt tensioner and possibly worn idler pulley, I will ask them to inspect the entire belt drive system. While the 350€-400€ repair cost is significant, its clearly better than risking complete belt failure and potential engine damage. Will the engine performance be noticeably better after replacing these components? My car has been running fine otherwise, but Im wondering if I might notice any improvement once the belt drive system is properly tensioned again.