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2008 LT 2.4L
On acceleration there is a loud buzzing from the rear, once the trans shifts it will cease, then as you accelerate uphill it will start again until you let off the gas or the trans shifts. I crawled under the car today checking for anything loose or hitting ( tubes, cables, springs, shocks, exhaust system.... cant find anything loose , hitting anything or rattles when hit or shook? What can it be? I already checked in the spare tire compartment so rules that out already. It seems to have to be some connection to the engine in order to transfer to the rear through the exhaust since that's the only connection to the rear? I did some research some point to a worn half shaft, mounts...ect but all look good.
Perhaps a video with sound and a test drive so we can hear it? Or we could guess , but there’s no prize for that correct answer. Look at the heat shield over the cat con, and the air box bracket, they tend to flex and break.
Does the buzzing sound like a bee ?
Or more like a rattle ?
More like a rattle, but there is nothing loose under the car that I can find. It doesn't do it all the time, but does it more often than not. Annoying as hell too. Only other think I can think of is inside the muffler or cat. The system has been welded like someone removed an aftermarket system and put this back on as there are some "spacers" welded in so the exhaust hangs a little lower than its supposed to and not tucked up where it should be.
More like a rattle, but there is nothing loose under the car that I can find. It doesn't do it all the time, but does it more often than not. Annoying as hell too. Only other think I can think of is inside the muffler or cat. The system has been welded like someone removed an aftermarket system and put this back on as there are some "spacers" welded in so the exhaust hangs a little lower than its supposed to and not tucked up where it should be.
My first thought to the rattle would be the exhaust.
You could have a broken baffle in the muffler.
It can not be in the Cat because there are no baffles and also the forward resonator that's after the Cat.
The system was hacked, it's not OEM.
Take a soft hammer (rubber) and hit the muffler.
Is there a rattle ?
At first, the buzzing sound strained me because I did not know its cause.
The reason was identified by accident - a working air conditioner. I don’t know what exactly buzzes in the air cooling system, but this sound is definitely there (of course, I'm talking about my car).
Turn off the air conditioner for a couple of days - maybe your buzz will disappear. Or you get rid of irritation, or narrow the circle of suspects.
