E90 Engine AC bypass/Whining Noise fixed-Problem diagnosed

A while back I started hearing a whining noise coming from my BMW E90 N52 engine. It sounded like a wind-up car or one of those little cars that kids drive. Sounded like the car was low on power steering fluid or that the alternator had gone bad. In fact, it was the AC compressor. This video details how to fix it and what steps you can take to solve the problem. Needless to say the sound was terrible, what's the point in driving a nice car that sounds like crap? Hope this helps you. Comment below with any questions you may have. I'm my instance the pulley had a bearing that was shot so I just replaced the bearing and kept the pulley but you can replace the entire pulley itself. Also check that your AC compressor refrigerant levels aren't low as sometimes that will cause a sound.
Usual belt size=78.5 inches, AC bypass belt=43.6 inches

[@josephfahie8147]

This is happening to me right now. It only happens when the ac has been turned on. But i want my ac to keep running so i guess I’m going to have to replace my bearings. Thanks for this video i almost thought i was gonna have to buy a new compressor

[@zero2infamous]

Thanks man this helped a lot

[@saldi3543]

thank you, I have the same problem with my car

[@jeffrey322]

Great videos! TY!

[@Acelapower1224]

my car was making the same noise, “2011 bmw 328i” have your car checked to see if the Refrigerant in the A/C system is low. I had my system recharged and the sound is gone. My mechanic said if it gets low on refrigerant it can start to make the noise. Hope this helps you

[@murphyr31]

Great video

[@cdawg2467]

Your video was a great help since my ac pulley just locked up which in turn shredded my belt and I needed to delete the ac on my 08 e60 n52. I picked up the exact dayco belt from advance auto which fixed my car. Thanks again bud.

[@serge8285]

😀

[@GOGGINSSHORTS007]

​@@serge8285how's it going I believe I'm having the same trouble my friend you see my bmw 330i makes a high pitch whining noise only when I park or come to a stop but when I accelerate or rev the engine it stop could your solution be my solution thanks in advance

[@serge8285]

@@GOGGINSSHORTS007no problem bud, try bypassing the AC compressor why not

[@serge8285]

it doesnt sound like you have a problem with your AC compressor, it would get louder or worse when you hit the gas if it did@@GOGGINSSHORTS007 but its always good to knowledge to have

[@unforgivable718]

I wish we could hear the noise you experienced. Either way, clever way to diagnose the issue.

[@serge8285]

it sounded like a bad alternator, like those toy battery powered cars that little kids drive around or like a remote controlled car everytime i rev'd the engine

[@l3bronthebeast]

came clutch ngl hopefully needed that belt spec fr

[@francotorres3034]

Hi thanks for your video ... I was wondering how did you approach to take out the pulley? Did you have to take out the hoses and the radiators? And or something else?

[@serge8285]

yes take off the things in front, you need enough access for the wrench to undo the compressor while the belt is still on....you could in theory approach from under the car but I had some long tools and went from the top

[@nogoodtrader]

So will any belt with part # 6pk1107 work? Thanks

[@Enthusiastlist]

Just noticed a hum on my e90 328i today, got a CEL right after I noticed it. At first I thought it was a wheel bearing until I got the CEL & I revved the engine in Neutral and still got the hum. Although the weird thing is it isn't sync with speed of the engine, but it does get slightly louder on 1.5k - 2k rpm. Gonna go see what the code is tomorrow. My hum to me sounds like it's coming from the left side but I could be wrong.

[@Nefrix1]

Have you dealt with the problem?

[@kaktusdima]

Great job describing, hank you, I am in same situation and now expecting new pulley. Did you change bearing with compressor on the car?

[@serge8285]

yes, kept the compressor on so I could loosen the pulley off the compressor....not a fun job

[@keygl0ck724]

@@serge8285 does this sound the same? It drives me crazy because I don't know what it is kzbin.info/www/bejne/eXutYpimbMuFaLM

[@serge8285]

@@keygl0ck724 it sounds similar....if you could film it under the hood and upload that would be better for me, it sounds like those little toy cars that kids drive in or those RC cars, very almost electrical sounding whine

[@florimbaj]

This is a great video can you please put the link where you got all the parts you needed for this job thanks

[@tonytjax9380]

Thanks for the video. Mine makes the same noise you described, but only with AC on! Turn AC off and it's quiet... Do you think the bearing is still the problem?

[@serge8285]

Yup theres no way the compressor is the problem if its blowing cold, that pulley is all done and its really just a 35$ bearing thats broken! its easier to replace the compressor entirely than take the pulley off itself but if you can lift the car then its prob worth it

[@AbdulHaq11901]

Did you have to remove the ac compressor when doing this?

[@anwarmohiuddin320]

Thank you for posting this video. This could be the problem I am having. I am currently on a road trip. Do you think it is ok to drive may be 1000 miles more with the noise (in my case the noise is intermittent; it starts at random times and goes away after 5min)

[@anwarmohiuddin320]

Thank you so much for your quick reply. The issue is the sound is comes on only when I am driving and when I pull over at the first opportunity I get, the noise is gone. This time I’ll try to pull over sooner and record it. I can sen you the video if you could please provide me your contact information or I’ll try to upload to KZbin if my bandwidth permits. I am a little paranoid as I have to drive a long way.

[@rytoniowendolini2793]

My noise is like a mini-horn and is from my secondary air pump. I put a new one on and its making noise at start for about a minute and goes away. I have no idea. Maybe I need a new hose.

[@milkmanisin]

How did you get the pulley off? Do you have to rebuild the compressor?

[@serge8285]

No, I left the compressor on and loosened the pulley off...did have to rebuild the pulley

[@steveazusa]

My whistling sound was due to a bad map sensor and causing a pressure leak, replaced it with an oem map sensor off Ebay for 115$ free shipping.. Service engine light gone, pressure leak gone whistling noise gone

[@EFRANEED]

Was it wasy to put it? How is the graph to put the new belt?

[@olivermweso6312]

what kind of circuit do you make on the pulleys with the new belt?

[@serge8285]

one that bypassed the ac compressor but not the other pulleys

[@Alekser82]

How difficult was it to replace the bearing? Did you remove the compressor or not? Since these are not available as separate parts from BMW, what is the bearing p/n you used?

[@serge8285]

kzbin.infoqolF22aYisw

[@serge8285]

35x52x12 bearing

[@JustWayve]

Bypass meaning don't even put the belt on the ac compressor? So just the water pump,crankshaft,alternator,idler and tensioner?

[@serge8285]

yeah you bypass the ac compressor with a shorter than usual belt, do not try and bypass the ac compressor with the full/standard belt

[@jwallace410]

Did you notice the whine getting louder during low speed turns? Mine just started whining, noticeably when the a/c was on and I would make low speed turns. Its Definitely coming from The pass. side of the car.

[@nocturnal7342]

jwallace410 same here, did you ever find out what it was?

[@serge8285]

yes, turning made it worse

[@kreshnikveliaj9741]

I got same issue it starts when i go up hill 3000 rpm and than keeps whining in stop and go traffic when you accelerate from a stop or a light at low speed and will go away when the road opens up and go over 60 mph

[@u.k.cheshirechap3113]

Hello I’m having issues with my bmw I have just made a short film and uploaded to KZbin. Do you or anyone have any thoughts on what’s up with it. No warning lights have appeared. Thanks

[@blairkeast9907]

U.K. cheshire Chap please send me the link to your video. Thanks

[@iamnormalandcanbetrusted]

tough to compare, I think mine is power steering but now I'm unsure, the whining noise is in sync with rpms but mine clearly gets real loud when wheel is turned all the way to left or right. but another weird thing is my ac is ice cold, but my heat only works on the left half of vents, Luke warm at best.

[@serge8285]

my noise would get louder when turning the steering wheel too but it was the AC pulley, try bypassing the ac compressor and youll know for sure

[@iamnormalandcanbetrusted]

@serge8285 I’ll try that thanks man

[@thejoker00009]

Did changing the bearing on the pulley resolved it, or u had to do something else?

[@serge8285]

yes it fixed the problem, the bearing in the AC compressor pulley was shot and it got rid of the sound, the same compressor is cooling my car to this very day many years later

[@hanynowsky]

Did you have the whining noise even though the AC was off? You should have visited an AC shop to empty your AC system and inject Specific Compressor oil + Freon gas. In most cases, this quiets the starving bearing.

[@serge8285]

Yes because even though the AC was off, the belt was still spinning the AC pulley with a bad bearing in it

[@ekilofomoode]

I hear this whining high pithed noise from my bmw also. The pulleys and fan belts have been changed and it’s still there. How do I send a video or audio of the sound maybe you can help.

[@99ekcouper]

Mite be a leaking valve cover

[@sexydes]

99ekcouper i think your right my bmw is making the whining noise right now also my valve cover seal is no good I have to change it so that has to be the reason for the noise 👍🏼

[@99ekcouper]

sexydes easy repair. Mite know someone who does side jobs. He’s a BMW tech

[@jenniferrosero725]

I have a bmw 2007 530xi. I hear that whining sound also. Which belt do I buy ? I also hear the ac compressor noise also. Thinking of buying a new one

[@serge8285]

I think you have an N52 engine or the same one I have so it would be the same belt, I feel 70% sure of it....

[@jenniferrosero725]

@@serge8285 what’s the name of that belt? I don’t know much about cars

[@NPlaysEdits]

i had the same sound, i changed my serpentine belt and the sound was gone

[@NoWorriesReef413]

Hey so I did this to my 2008 328 worked great for a few weeks and then the belt shredded this has happned twice just wondering if anyone else had this issue

[@serge8285]

you should not bypass the ac compressor with a shorter belt forever, its only meant as a check to diagnose the broken pulley

[@michalbrom6843]

could you hear difference on idle between AC on and off?

[@serge8285]

no because the belt still spins the AC compressor pulley

[@AbdulHaq11901]

mine only happens when ac is on

[@izyfication]

Any fix for this problem except changing the belt,

[@Acelapower1224]

my car was making the same noise, “2011 bmw 328i” have your car checked to see if the Refrigerant in the A/C system is low. I had my system recharged and the sound is gone. My mechanic said if it gets low on refrigerant it can start to make the noise. Hope this helps you

[@trevorphilps9599]

How can I bypass the AC? To disconnect it completely??

[@serge8285]

you need a shorter belt www.bimmerfest.com/threads/ac-bypass-belt.962657/

[@Ynai07]

Hi guys if it safe to use my car if i have this whining noise?

[@serge8285]

Maybe, but I don't know exactly what's wrong with your car

[@veeshalseebb8297]

Hello. Can we know the bearing no please?

[@serge8285]

35x52x12, google that and it will come up

[@hunchohuncho860]

Will this work for my 2006 325xi

[@serge8285]

Ahhh i dont know for sure but probably, check out the belt map for the n52 and the n53 to be sure

[@hunchohuncho860]

Can you give me the belt # and make on front of box video moves to fast..

[@serge8285]

@@hunchohuncho860 43.6 length belt by Dayco 6pk1107, 5060436 pause the video at 1:23

[@DrivingWithJake]

Did the noise before sound like this? kzbin.info/www/bejne/nqLRlneYr62igLc Trying to figure out my noise issue seems to only happen when not running and the door first gets opened etc.

[@serge8285]

no

[@joegoh1968]

turn off the aircon and if the whine disappears .. you know it is the compressor.

[@serge8285]

in my case the the whine did not disappear when turning off the aircon because the bearing in the pulley was bad and would still spin regardless

[@joegoh1968]

@@serge8285 I see .. for me, it only whines when the compressor clutch is engaged.

[@serge8285]

@@joegoh1968 yes i bypassed the compressor entirely to isolate the noise

[@erenoglu]

kzbin.info_xuKyf_j83w?feature=share Hello friend can you chek my sound if its the samw. Only on 1100 rpm also driving second vid on my page.

[@EnriqueVelasquez]

Can you help me with this noise? kzbin.info/www/bejne/mJmleoZ5qp2orbM

[@serge8285]

you have the same issue, shitty bearing in a pulley most likely....

[@tanishungry]

Hi check out my Vid Pls help me 😂😂😂. kzbin.info/www/bejne/iWi1pWR7jZhlhbM

[@serge8285]

ya dude change the pulley if the AC works fine and cools normal

[@IlMemetor72]

These fking engines i swear

[@serge8285]

the engine itself is great, my AC compressor pulley starting making a whining noise after 220,000km and it didn't prevent the car from cooling it just sounded bad haha