Hey everyone, first, thanks for taking time to read this. So i just bought a 2005 V6 Mustang (automatic) and whenever i have a passenger in the car i hear a whirring noise
that seems to be coming from the mid to rear end of the car. I only hear it when i accelerate or hit a bump and never when i brake, also i dont hear it at all when im driving alone.
the more weight i put in the car other than myself the more pronounced the whir is on acceleration. tried bouncing the car a little on the front and back and i dont hear any noise.
I have no idea what im doing to be honest but any advice would be very much appreciated.

 

It's usually the differential making noise, and with another person, it's more
weight on the drive-line. If it is the DIFF, it's usually pinion preload. If it is
howling under acceleration at various speeds, indicates that the gears are
already worn out or are out of alignment or depth with each other.

If you notice that the howling noise only occurs during deceleration, then
it is a good indicator that the pinion-bearing preload has loosened.

Rumbling and whirring noises at speeds over 20 mph, can be worn carrier bearings.
Generally, worn out pinion bearings can create whirring noises at various speeds,
during deceleration and/or acceleration.

So, it can be many things...