Screeching sound on cold start (Video)
 

Every morning after a cold start I hear a loud screeching sound during the first minute after startup. The screech is random so it could occur in the first 10 seconds or occur after 20 seconds and last 15 seconds but it does occur on every cold start.

So I take the car to the dealer and he advices that I will need to leave the overnight so he could reproduce the sound. The next morning he says he could not hear anything so we mutually agree to leave the car for another night and he tries the next morning and he doesn't hear anything again. Since he couldn't reproduce the sound he couldn't work on it but he adjusted the belts, tensioner, etc.

Now I bring it back home and the next morning I hear the screech and everyday since. Could it be that the car gets a lot colder since it's parked in the garage vs being outside on the lot with the dealer?

The video can be viewed at YouTube - X5
PS Notice the screech right after startup and then it builds up around 30 seconds into the video for about 5 seconds.

Check your drive belts.

petener999: Thanks for your reply buy "according to my service advisors" they were checked/adjusted.

Do a thread search on pulley noise. I posted a video with the same noise. I changed the idler pulley, tensioner pulley, and both belts. The tensioner pulley and belts looked to be in good condition. However the idler pulley had bad bearings.

Again check out the videos that I posted there you can see me spinning each pulley individually. A/C pulley spun a bit easily too. But I didn't switch that out.

Noise is gone during cold morning starts.

Have them look at your belts tensioner. I had the same issue with my car, after replacing my belts the screeching disappear.

Just to add... I played the whole driving back and forth to dealer game. Not a peep when its there overnight. Finally decided to fix it myself.

started at 8K miles on the odo. Now at 12K. '06 3.0i. kinda sad.

Hi there,to me it sounds like a secondary air pump,I had the same noise when the internal blower was getting bad...and it makes sense why it's always a short run on the cold start,get it checked...

Thank you for all your replies but although I may be able to pull off a spark plug replacement, I am not that handy when it comes to auto belts/pulley. Is there something specific I can tell my SA since I have only 3-4 months left on my factory warranty and I want to get it fixed before it expires. Also is this causing any damage to the engine?

Secondary air pump is injecting an air into exhaust on cold start up to reduce the emissions,no interaction with the engine as it's an electrical pump that sounds as a hair dryer,notice that sound on the video,when the pump stops blowing/working your squeaking stops as well...
You'll see,there's no pulleys involved.

Just show them the video.

Bumping an old thread as this issue is back and the X now has about 90K miles on it. Did not do anything the last time I posted on this thread and the noise went away. But this time it is still intermittent and if it does sound screeching it does not go away until the engine is shut down.

I did look at the videos posted by Foose and the sound it pretty similar so I think I will start by replacing the belts and the pulleys (since they are due to be changed anyways). But I am little confused by the which pulleys I will need to replace. There is a tensioner pulley, idle pulley, ac pulley?. One of them has a mechanical and a hydraulic option. Would/should I need to replace all of them? Anything else other than the belts and the pulleys that I should take care of?

Thanks

It's like a pair of shoes, when the right shoes soles or heel is worn away, do you just replace the right shoe or do you replace it with a new pair?

Thanks for your reply. How would I go about finding if I have a mechanical or hydraulic tensioner?

Thanks,
Entering my vehicle information in RealOEM shows a hydraulic belt tensioner. So that would mean I just need to change the pulley and not the entire hydraulic tensioner?

So here is a list of parts that I can gather that I need:
11281748131 - Tensioner pulley
11287512758 - AC tensioner assembly
11287841228 - Deflection pulley
6PK1538 - Serpentine belt
4PK0865 - AC belt

Does that sound like all the parts that I will need? Do I need to replace the hydraulic tensioner (11287838797) as well?

Thanks

get a stetha scope to narrow down the noise, you will be able to pin point it for sure. could be the alternator bearings going.

I am really hoping its not the alternator as that sounds expensive. :(

Just took a peek and it's hard to see with the fan in place. But I noticed the mounting bolt cap protruding (pic attached) which looks like its part 19 on realOEM. (RealOEM.com - Online BMW Parts Catalog). The mechanical tensioner does not seem to have something like this. Does that look right?

is it just me or does that belt not look routed correctly?

Oh well I'll just order the hydraulic pulley for now. Thanks for all the help.

That's a top down pic. Is it even possible to incorrect route the belt and have the car start up and run? I hope not!

It's possible, but I just got home and looked and its fine. Something was throwing me off.

another step would be take the belts off and check each pully, (alternator,power steering,waterpump, and tensioner pullies .

The sound is intermittent so not sure if I will be able to recreate the sound by hand. I have already ordered the since they were due to be replaced anyways. But if there are some tricks to verifying them by hand I'll do it before I replace them. Thanks

just check for play there shouldn`t be any.

Just wanted to let you all know that I completed this repair yesterday and no more screeching noise. I replaced the ac belt tensioner, deflector pulley, hydraulic tension pulley and both belts using this excellent DIY:
http://www.xoutpost.com/bmw-sav-foru...ent-3-0-a.html

Some notes:
1.) The DIY lists T50 to loosen the ac belt tensioner but I found out it's a T60. I did not have a T60 but was able to loosen it with a T55.
2.) For removing the ac belt tensioner there is only one bolt that needs to be removed after the belt is off. Not sure what the upper bolt in the DIY is for?
3.) All of the old pulleys spun freely unlike the new pulleys which had a little resistance to them. Before starting the repair I thought it would be opposite where the old pulleys would not be turning freely at all and jammed up causing the screeching sound.
4.) Putting the fan shroud back was a little tricky (took a couple of tries). There are clips on the radiator that the fan shroud slips into and getting them all in with one hand while holding the fan with the other hand was a bit of a circus (at least for me).

Overall this was an easy-medium DIY with the proper tools. I must have spent more time looking for and retrieving a socket, that I dropped while tightening the defector pulley, than the actual pulley and belt replacement.

Thanks for all your help.