Whining noise on acceleration

I have a 98 Ford Explorer. When I accelerate, I hear a whining noise that sounds very similar to tires. I can’t tell if it’s from the front or the back or which side it’s coming from. I suspect a differential problem or possibily a vacuum leak. What do you think it could be?

have you tried to check out the things you suspect to eliminate them one at a time?

  1. do you get the noise if you put it in neutral and rev the engine? Do you hear the noise in idle? If no, it is most likely not the vacume leak.
  2. If you put the rear up on jacks, and the tranny in gear and give it a little gas, does it make the noise? If not, while it may not rule out the differential, it reduces the suspicion that it is the problem. (dont do this in front of a wall or a person ect. in case it falls off the jacks stands.)

OK, I don’t think it’s a vacuum leak any more. I only hear the whining at highway speeds. And it goes away as soon as I take my foot off the gas.

If one of the bearings on an accessory is wearing out it will start to whine or screech when under load, but not so much when it is free running, but this doesn’t sound too much like that. You will usually hear that at low speed acceleration. This sounds more like tires to me. Check the air pressure. Are all the tires the same tread?

It could be an exhaust leak, but it could be any of the other suggestions too.