Hello.

New problem with our '88 944 Automatic. There is a moderately loud "whine" coming from the rear. It is definitely associated with vehicle speed, not motor RPM. The pitch of the "whine" increases as the car speeds up, and does not change when it shifts. The whine becomes noticeable at about 30 mph. It is only present when applying power. Backing off on the accelerator (coasting) causes the noise to stop, also shifting to neutral. And it resumes when applying power again.

To me, it kind of sounds like an old tractor gear noise (like when my Grandpa used to put it in "road gear"). My wife and daughter call it a jet engine noise.

I have tried replacing the differential fluid, and this did not change anything.

Transmission fluid level is appropriate.

Otherwise, everything is working fine. The AT shifts smoothly, no strange vibrations, etc. No noticeable issues with left or right drive shafts or boots.

Any thoughts would be appreciated! I've tried searching for other posts, but none that I found quite matched my symptoms.

Thanks!

 

Sounds like worn bearings in the diff. Mine does something similar but when I coast in gear.