[geordie]

Has anyone else experienced this? Particularly on cold start the heat sheild rattles underneath the x3 in a very annoying way, you can hear it with all the windows up.

Once it's warmed up, it dies off a bit, but it's definitely still noticeable. Really makes the engine sound cheap.

[Lotus7]

Originally Posted by geordie

Has anyone else experienced this? Particularly on cold start the heat sheild rattles underneath the x3 in a very annoying way, you can hear it with all the windows up.

Once it's warmed up, it dies off a bit, but it's definitely still noticeable. Really makes the engine sound cheap.

Are you sure it's a "heat shield" rattle and not the "normal" direct injection cold start sound? BMW direct injection engines tend to make high frequency "rattling" sounds, especially for the first 20 or 30 seconds after a cold start-up. Usually, it's just the high-pressure injectors' normal sound. Typically sounds like a couple of bad hydraulic valve lifters.

For some reason it’s more noticeable in the X3 than a 535i, for instance, but it is audible in a 5-Series with the hood open. Of course, not having heard the sound on your specific car, it could really be a heat shield.

The auto transmission torque converter also makes a "normal" rattling sound which can be heard outside the car if the rubber access plug on the passenger side (vehicle right the US) is not in place or not fully seated. That plug is very easy to dislodge and if not installed perfectly, will fall out of the bell housing covering the torque converter. I believe there have been several 28i owners whose cars were apparently delivered without the plug in place.

[geordie]

Just by way of an update on this:

I finally got around to taking the x3 into the dealership to get the rattle looked at. According to the dealer, the rattle is "normal" and is not the heat shield rattling against the exhaust components, but is caused by a 'small exhaust flap' that BMW puts in the exhaust pipe system to regulate emissions or something.

That may well be what's rattling, but it's still loud as hell. So now i'm stuck with "that's normal, please go away sir".

[Dukat]

Originally Posted by geordie

Has anyone else experienced this? Particularly on cold start the heat sheild rattles underneath the x3 in a very annoying way, you can hear it with all the windows up.

Once it's warmed up, it dies off a bit, but it's definitely still noticeable. Really makes the engine sound cheap.

My IS250 developed a start-up rattle that sounds just like yours. It never does it when I ask someone to listen for it and now my warranty is up. I love my rattle. It's distinctive.

[BMWZ4]

Hey Geordie,

See this link for a similar issue I had, which was fixed as part of a tech service bulletin. See post #9....once they had installed these 2 caps, the noise was gone.

Worth a shot.....

http://x3.xbimmers.com/forums/showth...t=engine+noise

Dave

[geordie]

Awesome thanks Dave!

I'm taking your post with the part numbers to the dealer today.

My x3 is a 3.5i but the noise problem sounds identical. Someone else on that thread mentioned that they were told the 35i had the plugs already but the 28i did not. I'll push it with the dealer and see if that's the case.

If this works, and they come out with a TSB for the RPM fluctuations, I'll have the perfect car

[Lotus7]

The plugs in question are not a very tight fit in the openings. I had my car (35i) up on ramps because I wanted to inspect the transfer case because of an unrelated problem and noticed that one of the torque converter housing plugs was 3/4 dislodged and ready to fall out. The other one was OK. At that point, the car had only about 1200 miles, so I'm convinced it was not installed properly at the factory.

The loose one was on the passenger side, so only made a difference in the audible noise level when the car was started in the garage (allowing the noise to reflect off the side wall).

The best solution is to "floor" the throttle more often. If the combination of exhaust and intake noise doesn’t drown out the torque converter rattle, the police sirens will.

[kolien]

I don't know if this can help you, but it reminds me of a similar problem I had when I owned an E46 320i a decade ago.

It too had a 6 cylinder petrol engine and the heat deflector vibrated making a rattling sound when cold. Easy to spot because the shield was sticking out on the side of the engine and when I touched it with my fingers (on cold running engine) the rattle stopped. The solution, bending the shield every so lightly in the middle, stopping the flapping movement of the sheet metal itself. Anyway the rattle sound stopped so I was happy with that.

I am not suggesting you start bend anything on your engine when you got a brand new X3. Leave it to the dealer to sort that out. I only wanted to share my experience with engine sound anomalies.

[Dukat]

Originally Posted by Lotus7

The auto transmission torque converter also makes a "normal" rattling sound which can be heard outside the car if the rubber access plug on the passenger side (vehicle right the US) is not in place or not fully seated. That plug is very easy to dislodge and if not installed perfectly, will fall out of the bell housing covering the torque converter. I believe there have been several 28i owners whose cars were apparently delivered without the plug in place.

Can someone take a photo of what/where the torque converter is and what the plugs look like? I want to check for the plugs when I pickup my car. Thanks!

[Lotus7]

Originally Posted by Dukat

Can someone take a photo of what/where the torque converter is and what the plugs look like? I want to check for the plugs when I pickup my car. Thanks!

The plugs are in the outer "bell housing" around the torque converter, about half way up on each side. The loose one on my car was at about 3 o'clock as viewed from the back of the engine - if that makes any sense. That housing is part of the front of the transmission, or just behind the engine. The plugs are made of black rubber and are about 3/4 inch wide and 2-1/2 inches long.

The only way you can see them is if the car is on ramps or a lift. The access is very limited, so taking a photo would be difficult. I was just barely able to fit my hand in the space to re-install the loose one on my car by feel.

I seem to recall that there is another small opening at the bottom of the same housing which is not plugged, so the two side rubber plugs are not going to stop all of the torque converter "rattle" from escaping the housing anyway.

[Dukat]

Originally Posted by Lotus7

The plugs are in the outer "bell housing" around the torque converter, about half way up on each side. The loose one on my car was at about 3 o'clock as viewed from the back of the engine - if that makes any sense. That housing is part of the front of the transmission, or just behind the engine. The plugs are made of black rubber and are about 3/4 inch wide and 2-1/2 inches long.

The only way you can see them is if the car is on ramps or a lift. The access is very limited, so taking a photo would be difficult. I was just barely able to fit my hand in the space to re-install the loose one on my car by feel.

I seem to recall that there is another small opening at the bottom of the same housing which is not plugged, so the two side rubber plugs are not going to stop all of the torque converter "rattle" from escaping the housing anyway.

Thanks for the explanation. I'll just hope I don't hear a loud idle, if I do at least I know what to ask them to look for.