[alex-t9]

2011 335xi
mhd stage 1+
Xhp stage 3

Ive started to get a faint whine from the engine bay that changes pitch with rpm. It's not noticeable to anyone but me but I'm certain it's new as I find it quite irritating.

I uploaded a video below. It's hard to hear in the video but far more noticeable in person. I've changed power steering fluid and no effect. It sounds like its coming from the alternator/power steerin pump area. Sound is there regardless if hvac is on/off. Doesnt get louder when I turn the steering wheel. My next step is going to be to start the car with the serpentine belt off and see if sound is still there.

Hoping someone recognizes the sound and can point me in the right direction! Thank you.

[NinetyEight740]

I’d guess it’s your tensioner. Shine a light down there and see if the sound seems to go along with the movement. You can also try spraying some lube onto the pulley and see if it changes.

[Lax1085]

struggled with a similar noise, it went completely away after changing valve cover. Due to bad PCV that's part of the Valve Cover. I could only hear the sound at idle, after it warmed up.

[renizer]

Originally Posted by Lax1085

struggled with a similar noise, it went completely away after changing valve cover. Due to bad PCV that's part of the Valve Cover. I could only hear the sound at idle, after it warmed up.

that's an interesting one! did you get any audio or video clips of that before changing maybe?

[Pladi]

Originally Posted by renizer

that's an interesting one! did you get any audio or video clips of that before changing maybe?

If you want to know that ur issue is the same as his, then just open the oil fill cap while the engine is running

It will stumble a bit because of unmetered air but the noise should go away. If it does then its ur pcv.

[renizer]

Thanks good advice Pladi, that makes sense! Will try but I think I've opened the cap once during running and didn't notice any influence but will do a dedicated check once again.

[SoCal_BMW_LA]

That's a pulley!!!! Same noise happened to me

[Pladi]

Originally Posted by renizer

Thanks good advice Pladi, that makes sense! Will try but I think I've opened the cap once during running and didn't notice any influence but will do a dedicated check once again.

As you probably know that pulley related issues should be taken very very seriously with these engines.

a PCV issue is generelly something you dont want but a belt system issue such as tensioner/belt/pulley is something that you really dont want. Any compromise on belt movement and there goes ur engine.. These german engineered engines will fail completely just because a belt slips or shreds.

You have an austrian flag i am sure you take no offence

Sorry it never ceases to amaze how a simple belt failure can cause an entire engine to fail.

So you take this simple noise seriously.

All the best

[alex-t9]

Finally solved my issue. I ran the car with the serpentine off and the whine was gone. Also spun all the pulleys by hand and noticed the steering pump made a faint sound/grinding noise. Replaced the steering pump today and noise is gone! Forgot how nice the n55 sounded....