just purchased a 2003 mercury mountaineer and it's makes a whining noise when you hit the gas and accelerate. Sounds like the wind up cars you have to pull back and wind up and let go of.. thanks

Could be a U-joint, Take it down the road and toss it in neutral and let me know if the sound goes away when you do that.

It does it even in park. I listened when a friend was giving it gas because i thought it was maybe a pully but it sounds like its coming from underneath the engine. it drives smooth but just really annoying whining noise..

Reminds me of the annoying sound my previous 2010 Mitsubishi Outlander AWD SUV 4 cylinder with CVT would make when I accelerated up to 40 MPH, but would go away at higher speeds. Kinda doubt that an '03 Mercury would have used a CVT though, probably a regular automatic transmission ( I could be wrong though).

While it is making the sound, turn the steering wheel to see if sound changes. It it does the problem is in the power steering.

Not power steering that was my first thought checked it quiet as can be . Second thought was maybe a pully but it doesnt make it when it sits in park only when I accelerate and it isnt at any certain speed you can just slightly give a little gas and it does it.. Mechanic wants to drop transmission and all to look and its going to run up to 450 to 500 bucks.. for him to do all.. Really to hate to pay that much when that might not even be the problem.

Did you take tension off the serp. belt tensioner pulley? If that bearing goes its heard mostly when putting a load on the motor. Worth a check, i've ran into it a couple of times. Hard to diagnose with tension on the belt, if you notice it with tension on the belt you are about to loose the belt and the tensioner :-) May not be your problem but I like looking for the basic things first.

You could take the serpentine belt off and start the engine to see if the noise changes or is gone. Certainly if you do this only run the engine a minute or two.

I have a 2003 mountinear and I go like 50mph and step of the accelerater and here a scraping noise that's a bit loud through the spair tire in the back. And it's not the brakes.

hi did you find out what it is ? mine is doing the same thing