Weird noise on E46 318i (N42B20)

Hi,

On the last couple of weeks I started noticing a strange "rattle"
sound coming from the engine bay.
The noise is can only be noticed around 1000rpm (like when idling
when cold) and goes away in higher rpms.

Today I removed the intake cover and recorded this video..

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

Any ideia of what is causing it? It looks like coming somewhere near
the throttle body or maybe the alternator beneath it.

Thx!

An easy way to identify the culprit is to get a length of pipe from
your local hardware store (about 3-4 feet of pipe will do) and use it
like a stethoscope. Hold one end next to your ear and touch the other
end to various engine components until you find the point where it is
the loudest -- that is your suspect part. Keep it away from the fan
blades and belts!!

Good luck.

RJD


On Sat, 7 Nov 2009 14:19:57 -0800 (PST), HangaS >
wrote:

>Hi,
>
>On the last couple of weeks I started noticing a strange "rattle"
>sound coming from the engine bay.
>The noise is can only be noticed around 1000rpm (like when idling
>when cold) and goes away in higher rpms.
>
>Today I removed the intake cover and recorded this video..
>
>http://www.youtube.com/watch?v=bjXqDoqOHhI
>
>Any ideia of what is causing it? It looks like coming somewhere near
>the throttle body or maybe the alternator beneath it.
>
>Thx!

Or you could use a long screw driver in the same way as RJD states.
Put the metal end to various components of the engine and 'listen' at
the other end.

Dunno if this car has metal heat shields but sometimes they come loose
and rattle at different RPMs. Although this does sound like a bearing
(alternator, AC tension pulley or AC drive or water pump, power
steering).

D

On Nov 8, 10:19*pm, RJD > wrote:
> An easy way to identify the culprit is to get a length of pipe from
> your local hardware store (about 3-4 feet of pipe will do) and use it
> like a stethoscope. Hold one end next to your ear and touch the other
> end to various engine components until you find the point where it is
> the loudest -- that is your suspect part. *Keep it away from the fan
> blades and belts!!
>
> Good luck.
>
> RJD
>
> On Sat, 7 Nov 2009 14:19:57 -0800 (PST), HangaS >
> wrote:
>
>
>
> >Hi,
>
> >On the last couple of weeks I started noticing a strange "rattle"
> >sound coming from the engine bay.
> >The noise is can only be noticed *around 1000rpm (like when idling
> >when cold) and goes away in higher rpms.
>
> >Today I removed the intake cover and recorded this video..
>
> >http://www.youtube.com/watch?v=bjXqDoqOHhI
>
> >Any ideia of what is causing it? It looks like coming somewhere near
> >the throttle body or maybe the alternator beneath it.
>
> >Thx!- Hide quoted text -
>
> - Show quoted text -

"Dave" > wrote in message
...
Or you could use a long screw driver in the same way as RJD states.
Put the metal end to various components of the engine and 'listen' at
the other end.

Dunno if this car has metal heat shields but sometimes they come loose
and rattle at different RPMs. Although this does sound like a bearing
(alternator, AC tension pulley or AC drive or water pump, power
steering).

Indeed, possibly even oil pump or main, but the latter gets bad at higher
rev's.

D

On Nov 8, 10:19 pm, RJD > wrote:
> An easy way to identify the culprit is to get a length of pipe from
> your local hardware store (about 3-4 feet of pipe will do) and use it
> like a stethoscope. Hold one end next to your ear and touch the other
> end to various engine components until you find the point where it is
> the loudest -- that is your suspect part. Keep it away from the fan
> blades and belts!!
>
> Good luck.
>
> RJD
>
> On Sat, 7 Nov 2009 14:19:57 -0800 (PST), HangaS >
> wrote:
>
>
>
> >Hi,
>
> >On the last couple of weeks I started noticing a strange "rattle"
> >sound coming from the engine bay.
> >The noise is can only be noticed around 1000rpm (like when idling
> >when cold) and goes away in higher rpms.
>
> >Today I removed the intake cover and recorded this video..
>
> >http://www.youtube.com/watch?v=bjXqDoqOHhI
>
> >Any ideia of what is causing it? It looks like coming somewhere near
> >the throttle body or maybe the alternator beneath it.
>
> >Thx!- Hide quoted text -
>
> - Show quoted text -

Thank you all for the tips.

Tomorow I'll try the 'stethoscope' technique on some suspect parts.
But if it is an isolate bearing it might not be easy to isolate the
noise with the 'stethoscope'.

I hope I find the culprit, at least just to know if it is something
that can pose a eminent danger to other parts or nor.
If it is just a bearing, i can live with that a few more day until
going to the dealer.. but I don't want a flywheel or something coming
loose
while driving.

Cheers.