Hi Harold:
Welcome to the Forum and congratulations on your purchase. You definitely should return under warranty, since there have been a few complaints from owners.
I'll cut and paste some of those comments I found while searching your particular issue It appears from what I’ve read that there have been a few issues as you have stated. Here’s one:
“When I decelerate I hear a whining noise coming from my rearend. Reminds me of some of my older cars from the 70's. Is this common or should I have it looked at? I have 14K mileage"
Answer:
"After a trip to the Ford dealer and 1600 bucks later I have a great car again. Hope this is the last of the problems.”
Another owner:
"I just got my 'Bird back from dealer for repair of whining in rear at 60-65 mph. They replaced gear set, bearings, shims and reset backlash. Noise gone. Mine is an '03 with 23k miles and premium care ext warranty."
Another:
“ I noticed a slight whine coming from rear after car was on road for a while -- first at 65-68 mph, then it seemed to be between 45-68mph after we got in traffic. Anyone else have a whining rear end and if so, was it corrected and what was problem?”
“Yes we had it too. You could hear the rear end whine upon decelerating from about 55 MPH down to 35 MPH. We had to have the rear differential gear set replaced (under
extended warranty) and the gear lash re-adjusted. It still whines a little on deceleration, but only from about 50 MPH down to 45 MPH. My service mechanic said that is the best they can do with the Ford gear sets now.”
Another:
“I kept hearing a whine from the rear of the Bird, especially from 40 to 65 MPH. It kept occurring while my foot was on the accelerator pedal, but would disappear when I took my foot off the pedal. I took it in for a 20,000-mile service and told my service rep about my concern. He had the mechanics look at it, and they ordered a new ring and pinion gear to replace the
OEM one in the differential."
Answer:
"Got it back today, total cost to the dealer was $438.22 for the rear differential gear replacement. We had to the pay the $50 deductible, for the
Ford ESP Extended Warranty work. It is good thing that we had the
Extended Warranty.”
Others:
“Only the ring and pinion? I had the very same problem on my '04 with only 2400 miles. They replaced the whole rear axle, half-shafts, and
rotors. I now have 6500 miles and no whine.”
“I Had The Same Whining, In The Rear End, At 45 Mph. They Replace The Differential, At 12000 Miles“
I hope these notes help. Good luck and please let us know how you make out!!