Rattle in exhaust on '06 X3 (3.0i Sport)

Hello all!

I bought a used X3 last weekend:

• 3.0i Sport
• March 2006
• 58k miles
• auto
• LOADED with extras!

It is a GREAT car! I love it. (Before that I had a 1998 E39 528i SE Touring and before that a 1994 525i SE - all great cars.)

One problem, though : I have noticed that there is a rattle/vibration coming from the exhaust pipe within a few seconds after starting from cold. It is loud enough that you most certainly notice it if you are outside the car and within say 30 feet, but I did not notice it when I was in the car and started it up this morning (but my wife called me later to say she heard it clearly as she waved me off from the living room window).

(I haven't noticed it occurring when the engine/exhaust is warm, but it is possible that it occurs then also.)

Also, when driving, I can hear the rattle (very faintly) at around 1,200-1,300 RPM. (The ironic/annoying thing is that when we carefully test drove the car, we noticed a whirring/rattling sound coming from the rear left hand side, but after a bit of poking around and careful listening, we both concluded that it was the sat nav unit whirring as it read the DVD disc and figured that that was either normal or fixable or tolerable. I have now deduced that it is in fact the exhaust rattling.)

Could you guys please suggest what the problem might be (presumably within the exhaust)? If you have a fair idea of the cause, do you think it is something that would fall under the full manufacturer warranty (which runs until March 2009)?

I might try speaking to the (independent) car dealer that I bought it from but (strictly speaking) he would not be obliged to do anything (but worth a punt nonetheless). If he won't help, I will have to try the warranty or else I will have to pay to have it fixed (which I never like doing...).

Thank you!

Matt

If it is truly coming from the exhaust, it most likely is the butterfly valve rattling in the tailpipe. They have been known to rattle on occasion. You could disconnect the vacuum line to the valve and see if that helps. If not, it's probably not the problem.
To disconnect it, open the rear side compartment hatch on the driver's side and you will see a servo there. Remove the side hose from it and the valve will now remain open at all times rather than only at full throttle. It gives the exhaust a deeper tone at idle too.

I am not sure if this applies to the X3 (I have not been underneath it yet), but heat shields on the exhaust can cause rattling noises. The intensity can change with RPM's of the engine or as you hit road bumps.

If that is the case, it should be an easy fix.

I just got this problem fixed. It was the butterfly valve. The tube to it was starting to rot on the end that conects to the exhaust. Just go to the delaer (or autozone) and you should be set! No more rattle!!!

Rattling butterfly valve is a classic symptom on 06 X3's. I have it, and another guy at my office has it.

It's not a sign of imminent doom. Probably a bad connection with the vac unit that controls the valve, or a bad vac unit. I'm blowing off my rattle until the next service visit.

I've read a couple forums, and one says to use the "golf tee mod" and others say to just unplug the hose. Do I need to plug the hose, or is it ok to just unplug it?

I had the same issue on my 09. I just disconnected the rubber hose going into the exhaust tip and problem went away. The valve only is for noise control, so disconnecting it won't hurt anything.