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      06-14-2021, 04:56 AM   #1
emiliogaines
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N46 Grinding noise from engine bay

Hi all!
I had this sort of grinding noise appear on my 2007 320i (N46).

I have talked to some people but no one can figure out exactly what the cause is and I haven't found a single thread where it makes this specific sound.

The funny thing is however that it ONLY makes this sound BELOW 1K rpm and ONLY DURING LOAD. For example starting in first gear or being in too low rpm for that specific gear. (< 1K).

It doesn't make this sound always either, some days it's not there at all.
I can prevent the car from making the sound if I start while keeping the car around 1K rpm as said above.

The video makes it sound a bit more screaching than it actually is but you get the point.

I'm using this car daily and has driven it quite far after this sound emerged, it's not something new.



Anyone have dealt with this specific sound before?
I already have changed cam chain tensioner.

Last edited by emiliogaines; 06-14-2021 at 04:57 AM.. Reason: Spelling
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      06-14-2021, 06:36 AM   #2
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Have you changed drive belt pulleys?
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      06-14-2021, 09:48 AM   #3
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Quote:
Originally Posted by TunafishE93 View Post
Have you changed drive belt pulleys?
I haven't but from listening to videos of bad pulleys I thought mine sounded different. Can I test it by spraying lubricant on them or something similar? I've spent too much money on this car and I really really don't wanna change something unless I know it's the culprit.
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      06-14-2021, 10:26 AM   #4
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You can spray it on the pulley bearing and this sometimes can work to diagnose things. However I think your best bet is removing the belt entirely and starting the engine and see if the sound still is there, that way you can point towards something that is driven by it or not
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      06-14-2021, 11:45 AM   #5
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Quote:
Originally Posted by E92_William View Post
You can spray it on the pulley bearing and this sometimes can work to diagnose things. However I think your best bet is removing the belt entirely and starting the engine and see if the sound still is there, that way you can point towards something that is driven by it or not
Def sounds like either a pulley is shot, or a heat shield is rattling something fierce. Try wiggling the pulley. If it has excessive play that's probably it.
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      06-14-2021, 03:00 PM   #6
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Quote:
Originally Posted by Vinnief96 View Post
Def sounds like either a pulley is shot, or a heat shield is rattling something fierce. Try wiggling the pulley. If it has excessive play that's probably it.
I'll pull the belt and check the pulleys tomorrow. thanks
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      06-15-2021, 03:06 AM   #7
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Quote:
Originally Posted by emiliogaines View Post
Hi all!
I had this sort of grinding noise appear on my 2007 320i (N46).

I have talked to some people but no one can figure out exactly what the cause is and I haven't found a single thread where it makes this specific sound.

The funny thing is however that it ONLY makes this sound BELOW 1K rpm and ONLY DURING LOAD. For example starting in first gear or being in too low rpm for that specific gear. (< 1K).

It doesn't make this sound always either, some days it's not there at all.
I can prevent the car from making the sound if I start while keeping the car around 1K rpm as said above.

The video makes it sound a bit more screaching than it actually is but you get the point.

I'm using this car daily and has driven it quite far after this sound emerged, it's not something new.



Anyone have dealt with this specific sound before?
I already have changed cam chain tensioner.
The one way clutch on the alternator pulley can cause really loud noises at idle on this engine. I have replaced quite a few of them. You can buy it separately from the alternator. Doesn't sound quite the same as your video though.
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      06-15-2021, 12:23 PM   #8
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Quote:
Originally Posted by Vinnief96 View Post
Def sounds like either a pulley is shot, or a heat shield is rattling something fierce. Try wiggling the pulley. If it has excessive play that's probably it.
Thanks for your suggestion. After checking the pulleys they all sounded good actually. I had my friend rev the car from idle and it sounds like the noise is coming from the left side of the engine. Maybe exhaust manifold or some heat shielding? The car was warm since I had to drive it to my friend so I didn't feel like sticking my hand down there lol.
Here is a new video.

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      06-15-2021, 02:13 PM   #9
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I'd check the connections from the downpipe/header into the exhaust. I've had one of those bolts come loose and cause a rattle. Also take off the plastic engine cover and see if there might be something under
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      06-15-2021, 05:59 PM   #10
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Quote:
Originally Posted by E92_William View Post
I'd check the connections from the downpipe/header into the exhaust. I've had one of those bolts come loose and cause a rattle. Also take off the plastic engine cover and see if there might be something under
Quote:
Originally Posted by E92_William View Post
I'd check the connections from the downpipe/header into the exhaust. I've had one of those bolts come loose and cause a rattle. Also take off the plastic engine cover and see if there might be something under
+1
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