Worn or broken motor mounts would cause the motor to rock back and forth when in gear and the accellerator is pressed. With the hood open, and have an assistant stand to the SIDE OF THE VEHICLE, and with the emergency brake ON, and with one foot securely on the brake and one foot lightly on the accellerator pedal, and finally, make sure the front of the vehicle is clear for a reasonable space, and finally use some common sense in terms of how much you'll be pressing the accellerator while the car is in gear, do the following:
Have the car in gear at a standstill, with the safety measures as mentioned. Press and release the accellerator a little in efforts to put a load on the engine. Do this in incremental "heavier" stages, but not to the point where it sounds like the engine is really laboring. It's not necessary to stress the components. If the motor mounts are bad, your assisant will see the engine rock back and forth, and you may likely feel a thud as you back off the throttle and the engine settles back onto it's mount due to plopping down on it's broken mount. That'll help diagnose if you have broken motor mounts.
In addition, you can SLOWLY lift the engine via the oil pan using a hydraulic jack and a support wooden block for cushion and observe the motor mounts if they have damage or not. Be careful NOT TO LIFT THE ENGINE TOO MUCH, risking cracking the oil pan.
A lift of 1-2 inches may be enough. Don't risk cracking the pan by anxiously pumping away at the jack handle.
You indicated "4-wheel drive" and the grinding only happening during turns. I'm not aware of a 4-wheel drive Windstar model. I thought they only come as front-wheel-drive. Regardless, the grinding during turns may be as simple as your tire riding up against the plastic splash-shield mounted on the frame of the car. If your Windstar is as I am familiar with, there is a small ABS plastic splash shield loosely mounted in the wheelwell. It tends to bend out of shape and can contact the tire tread during tight turns, making a horrible sound. Either drill some holes and add some bolts/screws or nylon push grommet thingies to steady the shield to the frame, or rip the small shield out completely. It measures about 18 inches long and a foot high. Perhaps a bit smaller.
If the grindinig is more of a metal-to-metal noise, I suggest consulting with a transmission shop, or checking your CV joints (but they tend more to click-click-click) instead of grind.
To end this long text, I doubt it's the motor mounts.
Wednesday, December 17th, 2008 AT 9:35 PM