Lets play "Name that noise"

[Sushibuddy]

1999.5 Pathy with 185,000 miles. My problem is we took a trip to the mountains 2 months ago and had our luggage on a hitch luggage rack. When we go up hill or begin to accelerate there is a high pitch noise coming from the back. I have noticed the noise without a load on the hitch only going up steep hills. Around town is no noise. We use the vehicle for a lot of road trips and want to take care of this problem. Any ideas? Thanks!
Modified by Sushibuddy at 11:01 PM 3/5/2010

[themadscientist]

Does it sound "rotational?" Does it increase in volume and/or rate as you speed up?

[Sushibuddy]

Yes sounds rotational. Only happens during acceleration and with weight added. The sound does get louder the quicker you accelerate.

It doesn't happen when it is just my husband and I driving in the car. One time we drove our neighbors to the airport with their luggage and it happened.

Thanks!