[JordynE92]

Hello, Im having some issues with squealing belt and wanted some inputs on it. The car is a 2012 335is with the n54 engine. 156k miles.

One morning i heard slight squealing noises coming from my serpentine belt and it continued to do so my entire drive to work. After work i had went to go start my car to let it warm up to leave work and the belt was squealing OBNOXIOUSLY, and didn’t stop. Let the car continue to run for maybe 5 minutes and the belt just shredded it self apart, I ran and shut the car off immediately so none of the belt would hopefully get sucked into the engine.

The next morning i went and got a tensioner replaced and a new belt by a small shop that was close to where the belt ripped apart.

Drove the car home from that shop (about 38 miles) and everything seemed good. The next morning i started the car to go to work and it was that slight squealing came back again. I let the car idle for a bit, then suddenly loud thunking noises from the belt shredding apart again. So again immediately shut the car off.

Now the SECOND time i just had all of the tensioners, pulleys, and belt replaced with all dealer parts. Car ran fine for about 2 days then this morning that slight squealing came back… but after letting the car idle for maybe 15 seconds it goes away.

Im at a lost for what could be causing this issue, i noticed that the past couple days have been colder weather and pretty damp so i’m not sure if it’s condensation getting onto the belt is making it squeak or anything like that. This is my First post just looking to get some inputs from anyone who has had this same issue.

Thank you, For your inputs.

[Eric BMW]

My engine ate a pair of belts before I found shredded versions of them in the oil pan stuck against the oil pump screen. Wish I had known about this apparently common issue.

I don’t recall where I saw it, but somewhere I read about an imbalanced power steering pump issue.

[lowrydr310]

Originally Posted by Eric BMW

My engine ate a pair of belts before I found shredded versions of them in the oil pan stuck against the oil pump screen. Wish I had known about this apparently common issue.

I don’t recall where I saw it, but somewhere I read about an imbalanced power steering pump issue.

It wasn't imbalance, there were two issues, only on the N54 apparently. One is interference where worn engine mounts would cause the engine to twist and the power steering pulley would contact the subframe. The other issue I read about was the plastic power steering pulley getting brittle with age and just crumbling. But I don't know how likely either of those issues are to happen. My 07 335 has the original pulley and it looked fine, and had well over an inch of clearance, closer to 2", between the pulley and subframe.

I do have this cold start squeal on my 330 N52. Belt, tensioner, and idler pulley were all replaced over two years ago. I don't have any oil leaks either. My PS pump is a bit noisy, so maybe there's a bit too much resistance when it's cold but I don't know for sure.