[1NS0MN1A]

Hi everyone,

Long time member, but haven't posted much lately. Wanted to ask a few questions and see if anyone could point me in the right direction. I am having two very interesting problems on my 2012 335is n54 with 40k miles.

1st issue: I am hearing a hollow pitched squeeking sound coming from the front wheels. I can clearly hear them corresponding to wheel speed, and it happens at every speed, not just low mph. It is not a loud noise, just dull and hollow, almost sounds like air chopping. It also can occur more or less depending on which direction i am turning the steering wheel, or if the shocks get compressed. I read previous threads, but didnt find any exactly like this.

2nd issue: This one has me beat, seriously. If I press the brake pedal VERY HARD, to the floor, the car fires up perfectly. If I press it half way down, it gives me a rough start. If I lightly press the brake, it turns and turns and turns, but doesn't fire up. I have two other BMWs currently, and they all fire up with minimal brake pressure. I have no idea what's wrong here, seems very odd to me.

I would like to work on these and fix them myself if possible. Hopefully some of you can chime in with some helpful information.

Thank you!

[djh2]

The brake booster is on the vacuum lines, maybe you have a leak and it only starts when the system is pressurized? Wild guess/generalized, but maybe somewhere to start.

[Donutz]

#1 sounds like a wheel bearing to me

[jt335i]

Originally Posted by 1NS0MN1A

Hi everyone,

Long time member, but haven't posted much lately. Wanted to ask a few questions and see if anyone could point me in the right direction. I am having two very interesting problems on my 2012 335is n54 with 40k miles.

1st issue: I am hearing a hollow pitched squeeking sound coming from the front wheels. I can clearly hear them corresponding to wheel speed, and it happens at every speed, not just low mph. It is not a loud noise, just dull and hollow, almost sounds like air chopping. It also can occur more or less depending on which direction i am turning the steering wheel, or if the shocks get compressed. I read previous threads, but didnt find any exactly like this.

2nd issue: This one has me beat, seriously. If I press the brake pedal VERY HARD, to the floor, the car fires up perfectly. If I press it half way down, it gives me a rough start. If I lightly press the brake, it turns and turns and turns, but doesn't fire up. I have two other BMWs currently, and they all fire up with minimal brake pressure. I have no idea what's wrong here, seems very odd to me.

I would like to work on these and fix them myself if possible. Hopefully some of you can chime in with some helpful information.

Thank you!

For issue #1, the air chopping noise you are referring to is it like a pulsating "whoomp whoomp...." noise like a helicopter that speeds up and slows down when you accelerate or decelerate, or, gets louder when slowing down to a stop? If this sounds like your case, then most likely it’s the wheel bearing. In order to check this yourself, you'll need to lift the front tires and check for any kind of play. That is, put your hands on the 9 and 3 O'clock positions and try to wiggle it and then put your hands on the 12 and 6 O'clock positions and try to wiggle it. There should not be any kind of noticeable movement. As a final verification, try spinning the tire. It should spin fairly freely and you should not feel any kind of resistance, but if the tire spins tight and you hear some strange grinding noise then it's definitely the wheel bearing.

These are video links with useful info which would help you diagnose it.

https://www.youtube.com/watch?v=OqFSRXA_RQA
https://www.youtube.com/watch?v=pilVew4cfnU

Had this same thing happen to a previous car I used to own (2003 350Z). My trusted mechanic, at the time, found the front wheel bearing on the passenger side was bad and after replacing it the pulsating “whoomping” sound was gone.

As for issue #2, can’t really help on that sorry.