I was driving my '06 and I heard a loud metallic buzz almost like a can full of BBs when I got to 5500RPM and it continued til redline. I was curious so I continued to try to duplicate the noise. After an afternoon of hard driving off and on, the noise seems to have gone away. Any ideas what it could be? The only thing I could think of was maybe a rock in the engine compartment somewhere rattling around. I remember when we used to use GM top engine cleaner to decarbon old Hondas (80's) it would make a noise similar to that but only if the motor was really carboned up. Any thoughts would be appreciated.

 

Well, if it can't be replicate and the car is performing fine, not sure what to say. Could have been you driving through gravel for all we know.

 

When I first got my car, the oil dipstick wasn't pushed in to the point where it clicked and it was making a funny sound only at certain RPMs. My brothers old Jetta had the area around one of the bolts on a heat shield rust away and it would make a terribly calamitous racket at times that sounded disconcertingly similar to a rod knock. Those are the only two things that come to mind.

 

Yea, I checked the engine compartment and the oil dipstick also. I did not find anything unusual. Maybe it was just a one day thing. I just hope it doesn't come back.