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c3uo 12-15-2012 05:42 PM

X3 35i - Exhaust Drone??
I have had my 2011 X3 35i for about 3000 miles now. It was CPO and has 20,000 miles. I am very happy with it except for the following annoyance: Exhaust Noise!

On cold start (at -15 C or ~20 F) it is VERY loud until the RPMs drop down to idle. I keep it in a garage and my neighbours have commented how loud it is. This goes away at idle and at least covers up the wastegate rattle which also happens at start-up for the first 30 seconds or so.

On the highway at 60 MPH I find the drone highly annoying. I actually slow down to stop it. My snow tires are quieter then the 19" M-Sport summers so it seems even more noticeable now. Whenever I go off the gas it's like Ahhh - no drone.

Is this normal? I have no local dealer. I want to rip off the exhaust and put one on from a 3 series. My old 3 was much quieter. I can't hear the sweet inline 6 over the obnoxious exhaust. Is it just me?

Any thoughts? Any aftermarket options?


leewtech 12-15-2012 06:35 PM

I think u have 2 issues. At cold start the exhaust runs through both outlets until the valve closes. Sounds awesome in my opinion. The highway drone sounds like tires to me not exhaust.

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c3uo 12-15-2012 07:11 PM

Yes - I think the cold start noise is normal. Loud - but normal.

The highway drone is definately not tires. If I let off the gas, put it in neutral it goes away. It is definately exhaust noise that varies with RPM. I'm just surprised the X3 35i has so much louder exhaust then the 335i.

Want the Thrill 12-15-2012 07:23 PM

Maybe the previous owner did the golf tee mod to their exhaust so it would be louder all the time. There are also other ways they could have done it. Check out this thread and then check out your vehicle. May be your answer:thumbup:

leewtech 12-16-2012 11:41 AM

Tire drone will be most apparent under acceleration and not coasting. Does the drone appear when you are in the coasting mode and revving the motor? Probably not.

The X3's body is basically a large open drum shape so it will resonate the exhaust note differently than a small 3 series' body style. That is why it appears to be louder.

c3uo 12-16-2012 02:46 PM

It's definitely exhaust drone (I can replicate it when revving the engine under no load). However, I've noticed it is worse when colder out, I suppose the internal muffler baffles may be less flexible and/or the body sound dampening may not work at low temperature as the steel is stiffer and resonates more.

I also took out the cargo cover a couple months ago which may have made it louder. I know it's louder when the seats are folded down. Maybe I could dynamat the trunk next summer.

02420X3 12-16-2012 03:12 PM

Carefully (it's hot!) check the exhaust when you do a cold start. If there is exhaust coming out of only the right side then it's normal. If there is also exhaust coming out of the left side then it has been "golf tee modded", either physically (by plugging a vacuum line) or electronically (by disconnecting a plug in the rear).

c3uo 12-16-2012 05:06 PM

At idle it's one exhaust only. I actually disconnected the electrical connector in the trunk a few weeks back to try it with both - but it was louder (go figure). The elctrical connector is reconnected and now the valve is closed at idle.

02420X3 12-16-2012 09:25 PM

OK, you're at least a step a head of me. Sorry, but that was the only likely explanation that I had.

Do you have access to a dB meter? I do, and I would be happy to measure the exhaust note on my 2011 X3 35i to give you something to compare to.

Vortec4800 12-18-2012 05:19 PM

Have you had the dealer check it out yet? What do they think?

Maybe you can try taking another 35i on the lot for a test drive and see if it's similar.

EDIT: Just re-read and saw that you have no local dealer. Not sure what to tell you then if you can't compare with another vehicle.

c3uo 12-18-2012 06:21 PM

Thanks guys. I'll try to look closer underneath over the holiday season and maybe see about a dB meter and/or reinstalling the cargo cover. I have noticed it seems much louder when it is below freezing, maybe the muffler baffles stiffen up our freeze and don't attenuate the noise as much.

cblandin 12-24-2012 07:44 PM

A layer of luxury liner pro from these guys might help:

I would NOT do the damplifier or dynamat space capsule bit - that stuff is really to quell vibrations in metal and does little to block airborne sound. The heavy vinyl on open cell foam is much more effective and mirrors what manufacturers use more closely. When I tried sound deadening my old '05 GTO it was actually most effective on exhaust noise (more so than the tire/road noise I was trying to reduce). I think hatchback style cars like the X3 are even more susceptible to noise.

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