Mercury Villager/Nissan Quest Power Steering

The wheel would be "almost impossible to move" with the engine off, regardless of anything else, unless you were going at least 30 MPH.

You may have an air lock somewhere.

First inflate the front tires to the maximum permitted for the tires. Make sure the reservoir is full, and that there is nothing against the front tires to restrict movement.

Now, turn the key switch to the run position, but with the engine still off. Apply a reasonable amount of turn to the steering wheel with your left hand. While holding this pressure, turn the key and start the engine with your right hand. As the engine starts, there should be additional movement of the steering wheel as the power assist is applied. If not, it sounds like your PS pump is faulty, or your fan belt is slipping, or missing. Did the belt jump off of the pulley? Did the belt finally work itself into the proper position, leaving the belt loose? Good luck.

Have you checked the other front end components? ball joints, tie rods, lower control arms...

I can push my car and steer it with the engine off - no real difficulty - a little heavier than with the engine running, but no real problem.

If you can't steer it at all there is something seriously wrong - It sounds like something is jamming the rack ..... since you appear to think it is related to the power steering, perhaps the PS ram is jammed internally..... you could try disconnecting the ram and then try to turn the steering wheel.

Alternatively it could be the rack itself which is damaged .... broken teeth or foreign objects jamming the teeth......

Either way it sounds like it needs professional diagnosis.

Thanks, did as suggested, solved problem. Lots of air, emptied reservoir, three times. sounds like you might work on cars for a living. Thanks again, it lives again! Satcom bill

No, not professional, just 40+ years of experience. Good luck with your car.

Good news. Thanks for letting us know.

Start by visually looking for a pinched hose or a crushed pipe.

1. Another item to check is the bearings at the top of your front struts, these allow the struts to turn as you steer. If one bearing has collapsed it will be very difficult to turn.

You could check this by lifting the front of the car off the ground, then attempting to turn the steering wheel.

as you are doing so have a friend look and listen for anything unusual from the front suspension, rack, struts etc.

2. another thought, if one of your caster rods has become disconnected, the wheel will be hard against the guard/wheel well and impossible to turn.....

Is there any fluid in the PS pump reservoir?