Buzz at 3000 rpm with 2006 M35x

[Bradleyroylance]

I have searched the forum and the archives for an aswer to this question and found nothing.

I have a 2006 Infiniti M35X. It has approximately 52k miles. For the past 6 months or so, I am hearing a buzz coming from the engine area or bottom of the car at 3000 rpm between 60-80 mph in 4th and 5th gear. This will happen in manual and automatic modes.

I have had it into the dealership twice now. They think wind is causing something to vibrate. They will tighten a screw, pull out some rocks, clip off a loose piece of plastic, etc., yet the noise is still there. The last time I was in, I was with the mechanic for two hours and he and I went on the road three times. The noise returned each time we hit the road despite all his efforts to stop a wind caused vibration.

I took it into another mechanic yesterday and they put it up on the lift and ran it at 3000 rpm in those higher gears and could not reproduce the noise. They took it on the road and did heard the noise. They did say that the left rear wheel bearing was humming and felt it needed to be replaced but did not think that could be the cause of the buzz.

Because so much has been done to eliminate the possibility of wind vibration causing the buzz, and because it only does it at 3000 rpm regardless of speed, I am now convinced this is not a wind problem.

I am thinking of strapping a microphone down there, hitting the freeway, then stopping, moving the mic, and repeating - until I find out where the buzz is coming from.

Any thoughts or help will be greatly appreciated.

Brad

[xxxalpinexxx80]

did you try it in neutral, just keeping it at 3k rpm, also the oil cover on the bottom of the M's can easily get loose and makes a funny noise. I would check the grill and make sure nothing is in there. Make sure all belts and screws are tight in the engine, and if you still can't find the problem i would just open it my self and fool around with everything, try shaking pieces in the engine terminal and such