BMW engine with slight rattle at idle

PMKeates · 15 Nov 2010 at 21:09

My engine has developed a slight rattle at idle. It definitely sounds to be coming from inside the engine and you can feel it if you touch the engine. If you rev to 1500 RPM, it more or less goes. If you drive at 3000 RPM steadily, it's barely audible. If you accelerate hard at 4000 RPM, you can hear this rattle. If you let off the throttle at 5000 RPM, you can hear something quite loudly. I've attached a sound clip of the idle noise.

Any suggestions?

Engine is a BMW M54B30 3.0L, which up until today was silky smooth and quiet.

http://www.mkeates.com/files/lol5.m4a

EDIT: To clarify, this was after a 60 mile driver.

EDIT2: Here's another sound clip of me driving around: http://www.mkeates.com/files/lol5_2.m4a

Lashout_UK · 15 Nov 2010 at 21:14

Collapsed catalytic convertor.

Loose or broken exhaust bracket.

Loose heatshield.

I'd get it on ramps and start with the exhaust system, before going any further.

Joe T · 15 Nov 2010 at 21:16

Same symptons as my loose heatshield on my e46.

PMKeates · 15 Nov 2010 at 21:18

Additionally, the car has no faults logged in memory, which I would guess a collapse cat would cause as it's monitoring that kinda stuff.

Lashout_UK · 15 Nov 2010 at 21:20

You'd probably dodge a code if a bit of it's got dislodged or smashed somehow, and is rattling around nicely!

[TW]Fox · 15 Nov 2010 at 21:21

Should have bought a high mileage 530i Sport m8

Morba · 15 Nov 2010 at 21:22

Sounds like the rattle I had on my e36, I think it turned out to be a heat shield that was got crap.

PMKeates · 15 Nov 2010 at 21:43

I just went out for a poke around and I can't see anything. Then again, it's dark, cold, and I've virtually no idea what I'm looking for, as I fumble about jabbing things with a trim brush.

The_Abyss · 15 Nov 2010 at 21:59

Never mind messing around with the wife - have a look at the car.

mjt · 15 Nov 2010 at 22:05

What did you buy in the end?

Scania · 15 Nov 2010 at 22:08

Another vote for heatshield.

PMKeates · 15 Nov 2010 at 22:12

mjt said:
What did you buy in the end?

The infamous automatic 530i that featured in Fox's and OllyM's sigs.

mjt · 15 Nov 2010 at 22:14

PMKeates said:
The infamous automatic 530i that featured in Fox's and OllyM's sigs.

Ah cool. What did Olly replace it with? Maybe I missed something..

Sorry for the OT

[TW]Fox · 15 Nov 2010 at 22:24

Olly hasn't got a car anymore.

NickXX · 15 Nov 2010 at 22:33

Haha, both these cars are still on OCUK. This place is so incestuous

Berger · 15 Nov 2010 at 22:41

NickXX said:
Haha, both these cars are still on OCUK. This place is so incestuous

Just don't shine a UV light on the inside.... :eek:

PMKeates · 15 Nov 2010 at 22:45

Whatever the problem is, I want it fixed tomorrow, as I am shopping at Westfield Wednesday evening and I cannot deal with dragging bags of clothes home across London.

PMKeates · 16 Nov 2010 at 07:32

(Un)interesting update!

The car was less noisy at idle when I started it this morning, in zero or lower temperatures. I left it idling for around 5 minutes and it was still less raucous, and after a short 10 minute drive, was still idling queter when I stopped. Whatever it is, it seems now to rattle less when it's cold.

Fr0dders · 16 Nov 2010 at 07:42

metal expands / contracts with changes in temperature so that points to heat shield / exhaust bracket stuff mentioned by others.

Both of them will be under the car so you'll need to get it on some ramps to take a proper look.

hurfdurf · 16 Nov 2010 at 07:47

PMKeates said:
Whatever the problem is, I want it fixed tomorrow, as I am shopping at Westfield Wednesday evening and I cannot deal with dragging bags of clothes home across London.

Westfield owns