[cjet68]

I have a 2011 335i N55. Just replaced the tensioner, 2 pulleys and the belt. The squeal was better for a day or two but it has definitely returned.

Hope to hear back if anyone figured out what causes this. Thanks!!

[whyzee125]

All the n55's unfortunately wobble. They are also known to fail so that very well could be the source of your sound. My friend did belts and pulleys, then the crank pulley balancer, then finally the fan which was the issue. Dead silent for about 300 miles til he spun a rod bearing at 72k lol

[Esixty1]

Hi team, sorry to revive an old thread. Unfortunately the resolution for this was never posted. Anyway, on the subject, in trying to diagnose a noise/harmonic with my N55, I'll try spraying water on the belt (used to use candle wax back in the day) to see if the tone changes. But was also wondering if it possible to run the engine with the belt removed for a little bit? Obviously it's not going to charge but is the ecu going to freak out if I try that? TIA

[At23]

Replying to see there was ever a solution. Same exact issue on my 2011 335i

[Marlin]

Bumping this. Trying to solve it as well. Going on 2 years with this issue and basically every part replaced.