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BnWBMW
07-11-2010, 10:31 AM
This week, when I go to work in the mornings, when I start my car I get this very high-pitched and very loud sound coming from the hood, and it sounds like a fan or a belt (but I could be wrong). As I drive the car, the noise loses volume, but it can still be heard, until about 5-8 minutes of driving after which either it is gone completely or it is just not loud enough to be heard in the cabin.

At first I thought it might be because of the cold weather, because this past week in particular has been very cold in the mornings. However, Friday the sun was already up for a while by the time I got to my car, so it was not nearly as cold as the days before...but the same sound still came.

The interesting thing is also that this sound only happened in the mornings....maybe it happens after you haven't driven the car for 8+ hours???

The other day I popped my hood and poked my head inside and the sound was pretty damn loud...I took a look at the belts that are visible from there and I didn't notice any of them off rhythm (then again I am not a mechanic, maybe it is something more subtle than that). Could it even be my radiator? Or AC compressor, maybe?

Can anyone offer any help on this?

TechFreak
07-11-2010, 11:58 AM
On most cars its the Alternator that squeals cos the bearings get really dry.

Usually you can sort it by spraying WD40 on it or some equivalent.........i'd try that 1st ! :thumbup:

http://theexpiredmeter.com/wp-content/uploads/2009/07/wd-40.jpg

I'd just give every moving part a very light spray ....don't go mad with it !

You'll need to remove the plastic facia panels from the front of the engine bay to get in there....

The right hand side facia panel is just 2 off plastic twist clips...

The middle facia panle is 4 off Torx screws....

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Expo BMW
07-11-2010, 04:09 PM
Can you take a video/audio? Does it still make the sound with climate control off?

SKT174
07-11-2010, 06:57 PM
I'm guessing it might be your Engine breather valve thingy (I forgot the name), I had both of mine replaced.

It was making a high pitch noise, much like one of those kettles on stove top that makes a high pitch noise when the water boils.

bghubr
07-12-2010, 12:07 PM
+1 Check out the CCV Valves

patshah
07-12-2010, 04:07 PM
It might even be a bad drive belt....

Country
07-12-2010, 05:41 PM
It's the belts. And possibly the bearings. Had the same thing going on back in December. I thought it was because of the cold also, but it wasn't. I had a coolant leak at the same time, so I just had all of the work done at one time. Runs smooth!!!!

BnWBMW
07-12-2010, 07:33 PM
On most cars its the Alternator that squeals cos the bearings get really dry.

Usually you can sort it by spraying WD40 on it or some equivalent.........i'd try that 1st ! :thumbup:


I'd just give every moving part a very light spray ....don't go mad with it !

You'll need to remove the plastic facia panels from the front of the engine bay to get in there....

The right hand side facia panel is just 2 off plastic twist clips...

The middle facia panle is 4 off Torx screws....

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.
.

Thanks Tech, I'll try that as soon as I can. Sounds very logical

Can you take a video/audio? Does it still make the sound with climate control off?

I will take a video next morning hopefully (since I can't replicate it, it only happens after I haven't driven for hours, AKA overnight...not that I would even want to replicate it on purpose)

I tried it with A/C off, yes. It still does same thing. However, that might still not matter because certain A/C problems like the compressor, etc, still occur with climate control off


I'm guessing it might be your Engine breather valve thingy (I forgot the name), I had both of mine replaced.

It was making a high pitch noise, much like one of those kettles on stove top that makes a high pitch noise when the water boils.

Yeah it makes a kettle-like noise that would be an accurate way of describing it

It might even be a bad drive belt....

One of these belts were on recall, and it was rotating out of rhythm, but it's not something I noticed, it was something that my mechanic uncle noticed and like I said it was something that is not urgent and that you wouldn't notice unless someone tells you it's there. That being said, once he told me about it, you pay attention to the sound and it becomes clear that it's there.

Anyway that piece was recalled (but I guess BMW didn't do a good job of informing all the owners) and the dealer replaced that I think it was like a year ago, so it shouldn't be that. Then again there are multiple belts and I don't know if that's the one you are talking about

It's the belts. And possibly the bearings. Had the same thing going on back in December. I thought it was because of the cold also, but it wasn't. I had a coolant leak at the same time, so I just had all of the work done at one time. Runs smooth!!!!

I had check coolant popping up like a month ago (it was weird though, it would come on, then it would be fine again after a couple seconds...but it kept doing it so I'm like what the heck and I refilled the coolant, didn't find any leaks, and now moved on. Doesn't seem to give me problems lately - knock on wood)


Thanks for the help guys. A lot of different suggestions so I have yet to figure out the root of this problem, but I like to know that I have a number of leads

Seven11
07-12-2010, 08:31 PM
i had the same symptoms and it was the belt tensioner

had that changed along with the belt

GKT33
07-13-2010, 07:26 AM
i had the same symptoms and it was the belt tensioner

had that changed along with the belt

I had the same thing and it ended up being a LOOSE belt tensioner. The main one to the alternator.:dunno:

BnWBMW
07-13-2010, 07:44 PM
I uploaded this video...you can't hear the sound too well from inside the car (in the last part of the video I was trying to catch the sound but my camera just didn't pick it up)

But it definitely can be heard from inside and the video doesn't really do a good job of representing the true sound since it's more high pitched than that, but better than nothing I guess

http://www.youtube.com/watch?v=t7meZ020ZKU