Rattling noises...is it serious?

[bimmer chick]

hey all,
i'm new to this...just signed up today, but i've been reading this newsgroup for the past few months. i just wanted to let everyone know that you guys have really maintained an excellent forum! this site has really guided me through my purchase...

I just bought an orient blue 330 Ci w/ M-sport package and i'm lovin it! however, i've been noticing some slight rattling noises coming from the bottom of my vehicle. the rattling only starts when i'm driving it for the first few metres after turning on my car...then it goes away. The odd thing is that this doesn't happen all the time. Should i be concerned?

bimmer chick
'04 330Ci M

[doeboy]

Not quite sure what you mean by rattling...

Is it a manual or steptronic transmission in your car? If manual, perhaps it's clutch chatter? Does it go away once you're in motion and off of the clutch?

[operknockity]

She says that it only happens for a little while after starting the car, so it sounds like something that takes a while to get properly lubed once the fluids are up to operating temp.

[bimmer chick]

It's Steptronic transmission. The rattling noise starts when i am in motion, but then when i accelerate to about 3K rpms...the sound goes away. not sure if this is serious since the rattling is not constant...is there an explanation for this?

thx!

[operknockity]

Can you localize the noise any better? Does it sound like it's coming from under the engine, directly under the passenger compartment, or from under the rear of the car? Also, can you be more specific about what kind of "rattling" it is?

[bimmer chick]

Can you localize the noise any better? Does it sound like it's coming from under the engine, directly under the passenger compartment, or from under the rear of the car? Also, can you be more specific about what kind of "rattling" it is?

It sounds like metal parts are clicking...and the noise appears to be coming from under the engine. I can only hear it when my window is down....so it's definitely external and beneath the car.

[doeboy]

It sounds like metal parts are clicking...and the noise appears to be coming from under the engine. I can only hear it when my window is down....so it's definitely external and beneath the car.

Hmm... lifters making noise perhaps? What's your oil level at right now?

[dynosor]

If the noise only starts after you start moving and not with engine start-up, I'd say its not valve lifters. If its a dull "dok dok dok" sound rather than a sharp click, its probably your shocks priming themselves. This is common on cars that don't have shocks with anti-drain down valves in their shocks and is of no consequence. BMWs do have these valves, but they don't always work perfectly on all shocks.

The valve's only function in life is to keep the working cylinder in the shock full of oil by stopping it from draining under gravity when parked to prevent noise.

I would have someone ride with you that can hang out the window to try and identify where the sound is coming from and if it coincides with small road imperfections. If its a shock, the noise does not affect its damping performance in any way except for the first 5 strokes it takes to prime fully - at low vehicle speed.

So you have a little noise, that's not a big deal. If it gets louder or bothers you, ask your dealer to listen - you will probably have to park it for hours to reset the noise, so it may be difficult to duplicate.

[Fast Bob]

Another possibility is a rattle in the (cold) exhaust system....after it heats up a bit, everything expands, and the rattle stops.

Regards,
bob

[bimmer chick]

If the noise only starts after you start moving and not with engine start-up, I'd say its not valve lifters. If its a dull "dok dok dok" sound rather than a sharp click, its probably your shocks priming themselves. This is common on cars that don't have shocks with anti-drain down valves in their shocks and is of no consequence. BMWs do have these valves, but they don't always work perfectly on all shocks.

The valve's only function in life is to keep the working cylinder in the shock full of oil by stopping it from draining under gravity when parked to prevent noise.

I would have someone ride with you that can hang out the window to try and identify where the sound is coming from and if it coincides with small road imperfections. If its a shock, the noise does not affect its damping performance in any way except for the first 5 strokes it takes to prime fully - at low vehicle speed.

So you have a little noise, that's not a big deal. If it gets louder or bothers you, ask your dealer to listen - you will probably have to park it for hours to reset the noise, so it may be difficult to duplicate.

Thanks! I'll take your suggestion...i'll have someone hang out the window to identify the sound. I'm sure it's not a major problem...but you've given me some useful knowledge.

[bimmer chick]

Another possibility is a rattle in the (cold) exhaust system....after it heats up a bit, everything expands, and the rattle stops.

Regards,
bob

This could be a possiblity as well...the noise only starts when i'm in motion...and once the car is heated, the noise goes away.

Is this common? I've never experienced this before on other cars.

[Fast Bob]

This could be a possiblity as well...the noise only starts when i'm in motion...and once the car is heated, the noise goes away.

Is this common? I've never experienced this before on other cars.

This is one of those problems that could potentially have a hundred different causes....when you consider the complexity of today`s cars, with their *thousands* of inter-related mechanical and electronic parts, it`s bloody amazing that they work as well as they do....

Regards,
Bob

[samlee4444]

It sounds like metal parts are clicking...and the noise appears to be coming from under the engine. I can only hear it when my window is down....so it's definitely external and beneath the car.

I'm pretty sure it's the same noise that i hear too. Does it sound more like when you drive over dried up leaves..almost like a crackling noise right?

It only happens at very low speeds. When you're driving next to a sound wall, or in a parking garage, the sounds echos off the walls, so that is the only time you can hear it if you have your windows down. You can't hear it if you're out in the open.

I took it into the dealership, and they couldn't find anything wrong with it.

MY 2004 330ci

[bimmer chick]

I'm pretty sure it's the same noise that i hear too. Does it sound more like when you drive over dried up leaves..almost like a crackling noise right?

It only happens at very low speeds. When you're driving next to a sound wall, or in a parking garage, the sounds echos off the walls, so that is the only time you can hear it if you have your windows down. You can't hear it if you're out in the open.

I took it into the dealership, and they couldn't find anything wrong with it.

MY 2004 330ci

it sounds like the exact same problem...I guess we'll have to live with it. I only notice it in the same places that you mentioned...the noise doesn't bother me too much. as long as i know it's not serious...our models must've been made on the same assembly line.