weird sound coming from engine bay when in idle
 

When the car is at idle at a red light it will suddenly make a sound like someones spinning the wheel of fortune. Does anyone know what's wrong with it?

:lmao: maybe ur getting the fortune.. no but it could the idler pulley

Get a hose and stick one end in ear, the other carefully around the pulleys or around engine bay until you find your sound.

Careful around pulleys and belts and fan! My preference for this cheap stethoscope is a 1" flexible electric conduit around 4' long.

Will help you zero in on exact component unless it's buried where you can't get hose to.

HTH

Doug

either...
 

Does it sound like, "a can of marbles"?

Possibly (I can't recall...) the DISA unit which has a flap which can break/rivet come loose or something and rattle. Located beside intake manifold.

It sounds like something broke and like a broken flap keeps hitting a fan. I have no clue what is it. this car has given me so much trouble lately ><

AC on or off?

Idler pulley is a good guess...but stick hose around to each of the pulley and you'll hear a distinct difference and be able to isolate it.

Check water pump, and make sure your fan isn't just hitting a stick that got caught in the fan shroud...make sure car is off and fan is off! Or remove--if manual, 3 mins., if auto, 5 mins. with proper tool...seemingly 50/50 without this magic tool...not familiar with it, but understand the theory.

Anyway, good flashlight, lots of looking...moving hose around...you'll find thing...then get picture from searching or taking and someone will know what part has failed.

Doug

Is the sound consistent? My car makes this exact sound at idle, but only during cold starts...and even then it only happens on about 3/5 cold starts..very strange because the sound goes away after like 15 seconds.

If your sound is constant I'd say you're lucky in the sense that you at least have time to figure out where the sound is coming from...I only get 15 or 20 seconds IF the sound comes on during a cold start.

Its starting to bug the hell out of me as I want to fix it before it becomes a bigger problem.

If you can, post up a video so we can know more or less exactly what it sounds like.
Somehow, our engines manage to produce a number of different "knocking" or "rattling" noises.

Im gonna go out on a limb here, but I'd bet if you turn your A/C off, the noise will stop.

I've realized when my wheel of fortune turns on during cold starts, it immediately goes away if I turn A/C off.
So what conclusions could we draw from that?

AC is OFF.
i will post a video of the sound tomorrow when i get a chance.
Also, this happens 9/10 times when i come to a full stop at a red light

Actually, I went in my car this morning, turned ac off and started the engine...wheel of fortune still came on.
I'm gonna spend all saturday tryin to find out what it is...I hope its something easy like a tensioner or idler pulley.

Will wait for your video...here's a thread I had started previously with some videos for your reference:

http://forum.e46fanatics.com/showthr...717&highlight=

I have the SAME problem!!! - just started recently, but def with the cold starts and only stays for a little bit and comes back on and off at red lights. Drives me crazy!

Remove the belts if the noise is still there(DO NOT RUN THE CAR LONG WITH BELTS OFF) then remove and check the DISA valve

Can the Disa valve really become that loud?

yes

another sound...
 

on a cold start, the injection? air pump runs for a period of time and shuts off. It's round, black top and over by-behind- the washer fluid tank. There is also a small vacuum hose with this unit which can rot/dry out... also, is it a vacuum valve there? can have problems rarely.

Removing belts for +/- :30 to :45 seconds is a good idea...

I figured as much it would have something to do with the secondary air pump (that black circular thing you described next to the washer fluid tank). Will check it out as well.

So you remove the belts and then start the car and let it run for give or take half a minute?

well...
 

You have to realize that the only "cooling" will be from the absorbtion of combustion heat into the engine metals and the water left in the cooling passages. The water pump won't be turning, moving coolant past hot spots and etc. and the thermostat will be closed.

Start from a cold engine rather than hot.

Don't run for more than 30-45 seconds.... If I had to do it on mine, I would, being very cautious.

A Chevy 327 with iron heads can take a trip around the block without any coolant... but a BMW?

Anyone else?

Right of course, it'd be completely ridiculous to leave it on for an extended period of time.
I've had my run-ins with BMW cooling systems in the past, so I know on what kind of balance they run.
Thanks for the heads up though.