BMW 5 Series Belt Tensioner Issue, Seeking Solutions

Hey there! I have some experience working on cars, and I actually dealt with a similar issue on my 1998 BMW 3 series last year. The belt handover mechanism failed on mine too, super annoying! After taking it to my regular workshop, they diagnosed a defective belt bringer mechanism. The repair cost me 455 Euro, but it fixed the problem completely. The mechanic mentioned these systems tend to wear out on older BMWs. Before I can give you more specific advice, could you share if you're getting any specific error codes? Also, does the mechanism make any unusual sounds when you try to use it? This info would help determine if you're dealing with the same issue I had.

Thanks for sharing your experience! Mine's at 46090 KM since I got it serviced last month. Before taking it to a mechanic, I've been trying to diagnose it myself. The mechanism doesn't make any clicking sounds anymore, and it's completely unresponsive. The error code I'm getting is P1643, which keeps showing up on the dash. Really appreciate the heads up about the repair cost, helps me budget for what's coming. Did your mechanism also stop responding completely before you got it fixed?

Hey again! Yes, my 3 series had exactly the same symptoms before I got it fixed, totally unresponsive with no clicking sound at all. That P1643 code is super familiar too, it's what my car was showing before the repair. In my case, the complete silence of the mechanism was actually a blessing in disguise, it helped the mechanic pinpoint the issue faster. When these belt handover systems fail, they usually either make a grinding noise (which often points to a motor problem) or go completely silent (typically indicating a failed belt bringer mechanism, which was the case for both of us). Since you're at 46090 KM, it's about the same mileage when mine started acting up. These belt handover systems in BMWs from our era are known to fail around this point. Looking back, I probably could've saved some money by addressing it when I first noticed small delays in the mechanism, but you know how it goes, you always think it'll hold up a bit longer! Just a heads up, make sure your mechanic checks the wiring harness too while they're in there. Mine found some slightly corroded connections during the repair, which they fixed as part of the job. Might be worth asking about that when you take it in.

Thanks for all that detailed info, it's really helpful! It's actually reassuring to hear that your car had the exact same symptoms. I had no idea about the wiring harness potentially being an issue too, so I'll definitely mention that when I take it in. It's funny you mention the early warning signs because mine was actually getting a bit slower for the past few months, but I kept putting it off. Guess we both learned that lesson the hard way! I've got an appointment booked for next week, so hopefully they can sort it out just like they did with yours. I'm just glad I'm not dealing with that grinding noise you mentioned, sounds like that could've been a bigger headache. I'll update you once I get it fixed in case anyone else runs into the same problem with these older BMWs. Really appreciate you taking the time to share your experience!

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