330ci engine rattle

[TIGA84]

As a complete technical numpty, heard last night a distinct rattle just before the engine died, didnt sound too healthy, was literally as you switch off the ignition, just before it dies.

Any ideas?

[FesterNath]

Could be slightly loose airbox, or something like that if it's not too loud. Mine does something similar, although mostly on cold start in the garage.

[wantmorepower]

i hear some sort of rattly vibration around 1200rpm under modest acceleration, always assumed it was exhaust related. not a loud noise tho

[XM5ER]

Tiga, if the 330 has a dual weight flywheel like the old e34 M5 then that is most likely what the noise is. Nothing to worry about.

[TIGA84]

XM5ER said:

Tiga, if the 330 has a dual weight flywheel like the old e34 M5 then that is most likely what the noise is. Nothing to worry about.

I genuinely have no idea, its a dec 2001 330ci (not sport),92k miles. Not sure on the flywheel situation. It sounds completely fine on start up,and running but had the door open when I turned it off the other evening and as I killed the ignition just before it went silent, there was a distinct rattle, not loud, but a plasticky loose kind of rattle, not engine related though from the sounds of it, more ancillary.

Still think the same on the flywheel front?

[WindsorRob]

I find the heat shield to my exhuast manifold on my 5 series rattle sometimes - just the sound of a mettally vibration - could just be this.

[wantmorepower]

Never understood what a dual mass flywheel was. I recall seeing mention of it in the engine specifications since years back (I recall the E34 535i having it)

Seemed strange to be adding weight here as it would reduce the engine's ability to pick up revs quickly, which is not something to be thrown away lightly. In fact one of the many desirable characteristics of the BMW straight sixes is that they love revs. Is it more to do with protecting clutch / transmission in some way, as this dual mass flywheel seems to appear on the torquier engines (and only with manual transmission)?

[XM5ER]

From your description, it sounds very similar. Certainly louder when you open the door and the last thing you hear as the engine stops.

[bags]

I have a similar issue with my 330i Touring. A metallic noise, like something is resonating, kicks in at exactly 5,500 rpm, especially in 2/3rd. I am off to get it checked by the dealer on Thurs. The sounds comes from the engine bay but very close to nearside front wheel. Strange....

Edited by bags on Tuesday 3rd July 14:06

[bags]

Thought I would follow this up, but not sure how relevant it is to the above problems. Feedback from the dealer shows that the sound is most likely to be coming from the alternator pully. They are replacing the pully and the alternator drive belt, along with some suspension brushes (I think - something to do with the suspension anyhow...). Mostly covered under warranty and I hope it solves it! It's blocking out the sound of the glorious engine!

[Aerofoil]

You checked you have oil?