2007 R56 hatchback, not sport, daily driver; 126,000 miles.

I tried to post this question earlier, must have done something wrong; apologies if this is a repeat.

When driving and RPM is between 1800 and 2200, there is a distinct, low-pitched buzzing sound that seems to be coming from the engine compartment, passenger side, down low or at least not at the top of the engine. Because at highway speeds of 55 - 65 MPH the RPM is around 2000 - 2100, the noise is with me always.

The sound is not loud but is clearly noticeable. When I start from standing stop, RPM reaches around 1800, the buzzing starts, stops when RPM gets above 2200. When I slow down into the 1800 - 2200 RPM range, buzzing starts back and continues.

Does not happen with cold engine. I cranked up Cooper in garage, dead cold, in PARK or in NEUTRAL, revved to 3000 and back, no noise. Drive about 10 miles, noise starts. With the noise sounding, if I stop, put transmission in either NEUTRAL OR PARK, rev to 1800 - 2200, the noise appears, disappears when RPM goes above or below 1800 - 2200 -- so, the noise is not related to moving, it appears at 1800-2200 standing still in NEUTRAL or PARK.

I say a "buzzing" sound because that's the only way I can describe it. It's not like the sound of a circular saw ripping through wood. When I was a kid, we would take a clothes pin and a playing card and clip the card onto the frame of our bicycles so it stuck into the spokes and made a buzzzzzzzzz as we rode bikes -- the sound is almost like that although not as loud.

Car has 126,000 miles. At 117,000: (1) replaced timing chain and all the parts associated with it; (2) drained and refilled transmission. At 115,000 replaced thermostat housing.

Car runs just fine, lots of power, no other problems. I'm two hours away from dealer.

Any ideas as to how many thousand $$$ this will cost -- whatever it is?

Thanks.

 

It sounds engine related (rotational issue); I'd start with a visual inspection for loose or missing fasteners on the front of the engine. My '09 was making a similar noise at idle, and it was the air filter resonator; the threads on the cylinder head were stripped out so I couldn't tighten the bolt. I installed a heilcoil. Now that the resonator is tight ... buzzing is gone.

 

Thanks. Cooper is now up on jack stands with front shocks removed, waiting for parts to install new shocks.

Meanwhile, I'll crawl all over engine top and bottom -- push, pull, wiggle everything I see, maybe find the problem.

Thanks for the tip.

 

Based solely on your descriptions, I would guess heat shield is loose somewhere

 

Had another car that manifested a knocking noise at cold start and a buzzing when everything up to temperature. Turned out to be a loose converter *brick*.

 

Thanks to everyone for your suggestions.

Cooper right now is up on jack stands with front struts removed; waiting on more parts to replace the shocks and put the struts back on.

I plan to spend Tuesday poking around the engine -- both running and not running -- top and bottom to see if I can find anything that's loose.