Rattle from front of Engine E46 M3

[Davidonly]

Noted some plastic sounding rattle from front of engine area in engine bay. At first only noticed with bonnet up. Seems to go away with any increase in RPM above idle. Now can be heard in cabin, but vanishes with tiny blip on throttle, to re-appear when idle settles again.

Does not sound like the engine/head/VANOS. Lower down and to right of the lump. I suspect a pulley bearing (alternator?) or fan viscous coupling. I have an extended BMW warranty, but fuss and bother getting it in for a check. Scotland in 2 weeks for 1000miles of beautiful roads and scenery. Should I be worried???

Advice appreciated!

Edited by Davidonly on Saturday 1st August 18:57

[mat205125]

If it's just something minor loose and vibrating (belly pan?) then no real need to worry .... Unless it comes off completely. If it's under warranty, get it checked

[Davidonly]

I guess I'll have to.........its such a miserable experience going to the Stealer

The noise is defo mechnical tho, rather than something loose, wondered what noises others had heard from pulleys/fans on M3?

[Davidonly]

No sign of rattle this morning! (5.00am start so cooler than of late). Thinking fan more now.....

[C8LNJ]

I went for a look at a 55 plate CS on Friday & upon start up it had a fair bit of front end rattle. Compaired to my 05 M3 SMG that is!!

I came to the conclusion that (due to various upgrade parts - AP 6pots, superprint exhaust & carbon intake, along with a heavily chipped front end) that it must have had a fairly hard life. Possibly used on track & suffering from a bit of wear maybe through oil starvation or something, maybe Vanos related? I walked away from it & back to the one I know

[n boost]

Possibily could be a weak timing chain tensioner as it works on oil pressure, therefore when you rev or blip the throttle it builds the pressure and gets rid of the slack/noise.

[MattOz]

Hi David,

Check the various pulleys as it could be that one of those is gently failing and causing the sound. I had a vibration damper (big pulley at the bottom ,linked to the crank) do this in an old 330d and it caused a rattle that was fairly difficult to pinpoint.

Matt

[Davidonly]

Matt,

many thanks, I guess with no noise for time being, its in the wonderful 'intermittent' stage of failure. OK for me as will keep warranty on it for a while longer as milage has dropped. Also not so worried about catastrophic failure whilst in the north in two weeks (can't wait)

Will point to damper when its finally into the garage. The car has been excellent up to now, only leaky side repeater and SMG microswitch so far in 23K and 2.5 years...now on 43K.

Love my M!

[Davidonly]

Where abouts are the timing chain tensioners in relation to VANOS unit, n boost?

[n boost]

When directly facing the engine the tensioner is below and behind the left(drivers) side plastic cover at the front of the engine below the vanos.
It is a big 32mm? size and is on mounted on the side of engine where the chin runs down.

[Davidonly]

Noise update: the rattle is now only obvious as you gently rev the car, with bonnet up, lasts about 0.5 seconds....sort of dull brrrr noise, I had an E36 325i with noisy vanos, but that was noisy throughout rev range.

Tensionser sound likely now, but car drives fine as is only noisy if you 'make' it do it by reving gently from idle.

Still doing my highland jaunt with it , but might have to book it in later this month. Will ask them to check tensioner, vanos and vibration dampers etc.

Warranty has an excess unfortunately

Edited by Davidonly on Saturday 8th August 13:04