[Sweeney921]

Hey everyone,

Wanted to see if anyone else with the B46 engine has experienced a mid-pitched tone that correlates with engine rpm, but is most noticeable around 1700 rpm. My biggest concern is the timing chain, but I'm also not ruling out that it could be as simple as an idler pulley.

I had my dealer look at it and they confirmed that I'm not just imagining the noise. They ran some tests but didn't find anything wrong so they proceeded to blame it on my ER aluminum charge pipe. Probably because that gives them an excuse to deny responsibility if they're missing some other issue. They're a real sack of shit dealership that treats their customers like idiots.

I'm going to re-install the OEM charge pipe then take it back to the dealer, but in the meantime I'm wondering if anyone else is having this issue?

[Sweeney921]

Reinstalled the OEM charge pipe and the noise is still there, as expected. Taking it back to the dealer this week to have it reassessed.

What's the best way to respond if the dealer says they can't figure it out? Do I elevate my concerns to BMW NA?

[Sweeney921]

Took a video in an attempt to catch the sound. It's faint, but definitely there. This noise happens in all gears, and also while parked.

[rjd_F30]

My car makes a very similar noise (N20) but not when idling. I can rev in park/neutral and it won't make the noise, but it will make the noise when driving, but it's not dependent on rpm. Situationally, it seems different than your noise, but sound wise it's damn near the same. Anyway, assuming the phone video didn't mute or dull the noise at all, sounds like the normal whirr of the engine to me.

[Sweeney921]

Originally Posted by rjdnyy224

My car makes a very similar noise (N20) but not when idling. I can rev in park/neutral and it won't make the noise, but it will make the noise when driving, but it's not dependent on rpm. Situationally, it seems different than your noise, but sound wise it's damn near the same. Anyway, assuming the phone video didn't mute or dull the noise at all, sounds like the normal whirr of the engine to me.

Thanks, I realize that this could just be normal noise for these engines. It's my first one with direct injection and turbocharging, so I'm sort of unfamiliar. Have you ever tried using heavier weight oil than 0w-20? Wondering if it would smooth it out at all.

My warranty is almost over, so I want to make sure there aren't any hidden issues. If there are then I just want them documented. My biggest concern is the timing chain since repairing it is an engine-out procedure.

[rjd_F30]

Originally Posted by Sweeney921

Thanks, I realize that this could just be normal noise for these engines. It's my first one with direct injection and turbocharging, so I'm sort of unfamiliar. Have you ever tried using heavier weight oil than 0w-20? Wondering if it would smooth it out at all.

My warranty is almost over, so I want to make sure there aren't any hidden issues. If there are then I just want them documented. My biggest concern is the timing chain since repairing it is an engine-out procedure.

Yah, always a good idea to get anything you're concerned about checked out, though my unprofessional opinion would be that this is just normal engine whirr.

I've never used anything but 0W-40 (at least as long as I've owned this car).

[eleven11]

I'm not well versed in the details of BMW's active sound modules (RPMs affected, etc.), but curious if that's a possible factor in your case. Disable (coding) and see if it changes, perhaps?

[Sweeney921]

Originally Posted by eleven11

I'm not well versed in the details of BMW's active sound modules (RPMs affected, etc.), but curious if that's a possible factor in your case. Disable (coding) and see if it changes, perhaps?

Good idea, it's worth trying out for diagnostic reasons. Will code it this weekend.

[kobluna]

The sound in video sounds about the same that I have in my N20. So I would say it's normal. But of course it's hard to tell for sure from video.

[Sweeney921]

Originally Posted by kobluna

The sound in video sounds about the same that I have in my N20. So I would say it's normal. But of course it's hard to tell for sure from video.

So I decided to swing by another dealer (BMW of Richmond) to see if they'd let me start up a new B46 to listen for the whirring noise I've been hearing. It made the exact same noise, so I guess that I'm actually just going a little bit crazy. More likely I'm just starting to notice some more subtle things the longer I own this car.

Case closed! BMW of Richmond was a huge help. Looks like a solid dealer with several limited production models. I counted 4 of the CS models alone.

Thanks for your responses everyone.

[DarkStarBimmer]

like a first time parent with a brand new baby you are just concerned. Glad that there was nothing to to get worked up about!

[Sweeney921]

A bit of good news, I switched to Liqui Moly 5w-30 and the whirring noise is completely gone. For reference, I used Twinpower Turbo 0w-20 for the first 45,000 miles.

[rjd_F30]

Originally Posted by Sweeney921

A bit of good news, I switched to Liqui Moly 5w-30 and the whirring noise is completely gone. For reference, I used Twinpower Turbo 0w-20 for the first 45,000 miles.

Nice, interesting solution though. I guess I'm not all that surprised, as you were using a pretty thin oil. What made you chose a 0W-20? I use 0W-40 for reference.

[Sweeney921]

Originally Posted by rjdnyy224

Nice, interesting solution though. I guess I'm not all that surprised, as you were using a pretty thin oil. What made you chose a 0W-20? I use 0W-40 for reference.

0w-20 is the recommended viscosity in the owner's manual, and I wanted to ensure that the factory warranty would protect me if I had any serious engine problems. 5w-30 seems to help the engine run a bit smoother, and with any luck it'll also make it last longer.

[rjd_F30]

Originally Posted by Sweeney921

0w-20 is the recommended viscosity in the owner's manual, and I wanted to ensure that the factory warranty would protect me if I had any serious engine problems. Hopefully a slightly thicker oil will help the motor last longer, and so far it at least seems to make it run a bit smoother.

Jeez really, shows how much I know about the B4x lol. Well at least you got 'er running better

EDIT: Just looking at a 330i owner's manual online, it recommends six different oil viscosities, then makes a note that only particular engines are ok to use 0W-20. Wonder what those "particular engines" are, and if you've got one of them.