My 1991 Nissan Sentra makes a buzzing-sound noise at about 3,000 RPM. It's been annoying since that's a constant RPM on a highway. I'm suspecting some loosened exhaust or some loose heat shield.
Yes, it easily could be but it makes it only at the highway speed, so it would be really hard. Jack it up, get under there and hit things with a rubber mallet, and if you hear something rattle, tighten it back on. You can watch my video "finding the sources of car noises" for pointers. There's a cool tool out there and I bought mine used for 50 bucks, that has a receiver and semi units. You just put the units around the car, put on headphones when someone else is driving your car and when you hear the rattle, you switch the receiver to the different broadcast units and figure out where the rattle is coming from. That’s really handy. You could also have a mechanic, such as one from YourMechanic, detect the source of the sound and make the needed repairs to have this issue resolved.
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