Center a rack and pinion from under the dash

Yes, something is loose.
Stop driving immediately before you kill yourself or someone else, and have it taken to a qualified mechanic for repair.

I would need to hear the noise

Have front end checked or if you know what your doing check rt yourself , could be a bad tie rod end,,to a bad rack and pinion

1. Jack the car onto stands and remove the front wheels.
2. Remove the drivers seat and the lower dash covers over the pedals.
3. THIS STEP IS VERY IMPORTANT. Place the steering wheel at center, and remove the key, to lock the steering column for the rest of the job. If you don't do this you WILL destroy the air bag clock spring under the steering wheel, and they are VERY expensive and fiddly to install.
4. Move the carpet / mats as necessary and undo the splined connection on the pinion shaft.
5. Drain the power steering fluid and disconnect the hoses from the rack. The hose connections will be very tight.
6. Undo the tie rod ends, and the two clamps that secure the rack to the frame. With some wiggling the rack can be removed.

Defective rack and pinion steering gear.

The whole rack & pinion does NOT move! Only the rod out of either end of it. If the main body, where the hoses connect, is moving the mounting bolts are missing, or broken.

Normally any vehicle with rack & pinion steering, that will not turn left equals a bad rack & pinion.
The "wont turn left" is the classic industry wide indicator that the rack & pinion is worn out.

Disconnect the column from the rack & pinion, And then see if the wheel will rotate left. If it does, then it IS the rack & pinion or some thing is jamming it. That is a classic sign of a bad rack & pinion. It takes more hydraulic pressure to turn left than to the right, and the and so the floating ball hits the seal harder, and wears it out faster. Then the pressure just returns to the pump in stead of moving the tires left.

NOTE: DO NOT turn the steering wheel more than it does when connected the the rack & pinion.
For this test one turn either way from center will suffice. If you turn it more, or fast, you will probably break the "clocking spring" inside the steering wheel. Then the air-bag warning light will come on. The spring tells the air-bag when its safe to fire the bag in relation to the wheels position.

Hope this helps.

since the rack is used it could be defective. aligning the vehicle will not loosen the steering up

Wheel alignment is probably off. Almost any garage can fix it with reasonable price (~50$).

The book calls for about 5 hours labor with a lift, air tools, and experience. It's a tough job. Here are a few tips, Take the lines loose from the rack; not the pump. With the tires off, Remove the nuts from the outer tie rods.Run the nuts back on the tie rods stud and hit the steering knuckle where the tie rod's stud goes through.This will free the stud. Remove the steering shaft from the rack.(take the bolt all the way out.Remove rack mounting bolts. Twist,pull ****,and fight the rack out the side of the car with the most room. The new rack will have inner tie rods already installed. Make sure the new rack is centered.(Turn left then right count the turns then center same # of turns from left to right). Count the threads or measure from the outer tie rod's jam nut to the last thread on the inner tie rod.(you can leave the jam nut in place and take the outer tie rod off and measure from the jam nut to the end of the rod.)Install the outer tie rods. Replace rack in car. hook up steering shaft.Bolt up rack. Hook up lines. Add fluid and work rack back and forth to bleed air. recheck fluid. Have it aligned. (or just take it to a shop.This job is going to be a nightmare!!!)