So I've had this whirling, winding sound under slow speeds during mainly deceleration (you can hear it under acceleration as well but the engine drowns out the sound)for about a month now. The thing is, the sound only occurs after I've driven my car for say 20 mins or so after its fully warmed up. The whirling and winding sound speeds up and slows down according to my speed and is coming from behind me so I'm pretty certain its the differential. The sound has become louder and louder over time. Can anyone confirm if this is indeed the differential or something else? If so, what measures should I take? I've recently tried changing the diff fluid but it hasn't helped.

My car is a MY2000, 97k miles, pretty much stock. Thanks in advance. Any advice/tips would be welcome.

 

What gear oil have you been using and for how long?

 

Last time I heard a noise that got louder as it heated up and went with road speed, it was a bad trans tailshaft bearing.

 

I've been using Amsoil severe gear 75w-110 for the last 20k miles or so.

 

The only way to be sure is to get under the car and listen.

Put the car safely and securely on 4 jackstands, remove the rear wheels, engine on, in gear (3rd or 4th) and ask someone else to rev the engine a bit.
It sounds dangerous but without the wheels on the car there is not much weight rotating.

 

I've done this as well. It also won't hurt to take a probe (screwdriver or stack of extensions) and listen against the diff and tailshaft of the trans to see where your sound is coming from. Be sure the car is secure.

 

Ok thanks guys, I'll give that a shot. Hopefully I can do it fast enough so it doesn't cool down. I still don't understand why it only makes the sound after 20mins of driving or so.

 

I'm a bit late to the party here, but I'm having the same exact issue and have been trying to figure it out forever. It only starts up around 20 minutes into driving and is speed dependent. Do you remember what the problem was?

 

Try running 75/140w. It solved my diff noise/groaning issue.

 

Do you know the last time the diff oil was changed and what was used? Also, how many miles on the car?